Journal articles: 'Ion interferometer'

1

Gomes, André D., Martin Becker, Jan Dellith, Mohammad I. Zibaii, Hamid Latifi, Manfred Rothhardt, Hartmut Bartelt, and Orlando Frazão. "Multimode Fabry–Perot Interferometer Probe Based on Vernier Effect for Enhanced Temperature Sensing." Sensors 19, no. 3 (January 22, 2019): 453. http://dx.doi.org/10.3390/s19030453.

Full text

Abstract:

New miniaturized sensors for biological and medical applications must be adapted to the measuring environments and they should provide a high measurement resolution to sense small changes. The Vernier effect is an effective way of magnifying the sensitivity of a device, allowing for higher resolution sensing. We applied this concept to the development of a small-size optical fiber Fabry–Perot interferometer probe that presents more than 60-fold higher sensitivity to temperature than the normal Fabry–Perot interferometer without the Vernier effect. This enables the sensor to reach higher temperature resolutions. The silica Fabry–Perot interferometer is created by focused ion beam milling of the end of a tapered multimode fiber. Multiple Fabry–Perot interferometers with shifted frequencies are generated in the cavity due to the presence of multiple modes. The reflection spectrum shows two main components in the Fast Fourier transform that give rise to the Vernier effect. The superposition of these components presents an enhancement of sensitivity to temperature. The same effect is also obtained by monitoring the reflection spectrum node without any filtering. A temperature sensitivity of -654 pm/°C was obtained between 30 °C and 120 °C, with an experimental resolution of 0.14 °C. Stability measurements are also reported.

APA, Harvard, Vancouver, ISO, and other styles

2

Gut, K. "Polarimetric difference interferometer made by ion exchange method*." Journal de Physique IV (Proceedings) 129 (October 2005): 109–12. http://dx.doi.org/10.1051/jp4:2005129023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Hu, Yan-Min, Wan-Li Yang, Xing Xiao, Mang Feng, and Chao-Hong Li. "Multi-ion Mach—Zehnder interferometer with artificial nonlinear interactions." Chinese Physics B 23, no. 3 (March 2014): 034205. http://dx.doi.org/10.1088/1674-1056/23/3/034205.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Grydeland, T., E. M. Blixt, U. P. Løvhaug, T. Hagfors, C. La Hoz, and T. S. Trondsen. "Interferometric radar observations of filamented structures due to plasma instabilities and their relation to dynamic auroral rays." Annales Geophysicae 22, no. 4 (April 2, 2004): 1115–32. http://dx.doi.org/10.5194/angeo-22-1115-2004.

Full text

Abstract:

Abstract. Several explanations have been proposed for Naturally Enhanced ion-acoustic Echoes observed at mid- and high-latitude Incoherent Scatter observatories. A decisive measure for distinguishing between these explanations is whether or not simultaneously observed up- and down-shifted enhancement occur simultaneously, or if they are the result of temporal and/or spatial averaging. The EISCAT Svalbard Radar has two antennas in the same radar system, which can be used as an interferometer when pointed parallel. In observations from 17 January 2002, between 06:46:10 and 06:46:30 UT, we used this possibility, in combination with direct sampling of the received signals, to yield measurements of "naturally enhanced ion-acoustic echoes" with sufficiently high resolution to resolve such averaging, if any. For the first time, radar interferometry has been employed to estimate the sizes of coherent structures. The observations were coordinated with an image intensified video camera with a narrow field of view. Together, this forms the initial study on the causal relationships between enhanced echoes and fine structure in the auroral activity on sub-kilometer, sub-second scales. The results confirm that the enhanced echoes originate from very localised regions (~300m perpendicular to the magnetic field at 500km altitude) with varying range distribution, and with high time variability (≈200ms). The corresponding increase in scattering cross section, up to 50dB above incoherent scattering, eliminates theoretical explanations based on marginal stability. The simultaneously observed up- and down-shifted enhanced shoulders, when caused by sufficiently narrow structures to be detected by the interferometer technique, originate predominantly from the same volume. These results have significant impact on theories attempting to explain the enhancements, in particular it is found that the ion-electron two-stream mechanism favoured by many authors is an unlikely candidate to explain the observations. The video data has helped establish a clear correlation between the enhanced echoes and auroral activity, on sub-second time scales, showing a threshold connection between the auroral intensity and the triggering of the radar enhancements. It appears that the up- and down-shifted enhanced echoes correlate with fine auroral structures in different ways. Key words. Ionosphere (auroral ionosphere; plasma waves and instabilities) – Radio science (interferometry)

APA, Harvard, Vancouver, ISO, and other styles

5

Zhang, J., K. H. Olsen, and K. A. Schoessow. "Quantitative measurement of surface roughness of TEM specimens." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (August 1992): 406–7. http://dx.doi.org/10.1017/s0424820100122435.

Full text

Abstract:

The thickness and the local thickness variation of thin film specimens are critical parameters for many types of AEM analysis. The local thickness variation of the thin film specimen can be estimated from the surface roughness of the specimen. TEM specimens of most materials, especially multi-phase materials, have rough surfaces as observed by secondary electron imaging. However, there is little quantitative assessment of the surface roughness because of the difficulty of specimen thickness measurement. In this study, surface roughness of TEM specimens prepared using chemical etching, electropolishing, and ion beam thinning was measured using a direct phase detecting optical interferometer. This interferometer gives a quantitative three dimensional map of the surface topography with a depth resolution of ∼0.7 nm by converting digitized light intensity at each point of a 1024×1024 array into the optical path difference using the three-measurement algorithm. The horizontal resolution of the interferometer (∼340 nm) is limited by optical diffraction and is poor by the TEM standard. The quantitative information obtained by the interferometer is complimentary to the secondary electron imaging in STEM or PEG SEM for characterizing TEM specimen surfaces.

APA, Harvard, Vancouver, ISO, and other styles

6

Schlatter, N. M., V. Belyey, B. Gustavsson, N. Ivchenko, D. Whiter, H. Dahlgren, S. Tuttle, and T. Grydeland. "Auroral ion acoustic wave enhancement observed with a radar interferometer system." Annales Geophysicae 33, no. 7 (July 20, 2015): 837–44. http://dx.doi.org/10.5194/angeo-33-837-2015.

Full text

Abstract:

Abstract. Measurements of naturally enhanced ion acoustic line (NEIAL) echoes obtained with a five-antenna interferometric imaging radar system are presented. The observations were conducted with the European Incoherent SCATter (EISCAT) radar on Svalbard and the EISCAT Aperture Synthesis Imaging receivers (EASI) installed at the radar site. Four baselines of the interferometer are used in the analysis. Based on the coherence estimates derived from the measurements, we show that the enhanced backscattering region is of limited extent in the plane perpendicular to the geomagnetic field. Previously it has been argued that the enhanced backscatter region is limited in size; however, here the first unambiguous observations are presented. The size of the enhanced backscatter region is determined to be less than 900 × 500 m, and at times less than 160 m in the direction of the longest antenna separation, assuming the scattering region to have a Gaussian scattering cross section in the plane perpendicular to the geomagnetic field. Using aperture synthesis imaging methods volumetric images of the NEIAL echo are obtained showing the enhanced backscattering region to be aligned with the geomagnetic field. Although optical auroral emissions are observed outside the radar look direction, our observations are consistent with the NEIAL echo occurring on field lines with particle precipitation.

APA, Harvard, Vancouver, ISO, and other styles

7

MORLENS, ANNE-SOPHIE, PHILIPPE ZEITOUN, LAURENT VANBOSTAL, PASCAL MERCERE, GRÉGORY FAIVRE, SÉBASTIEN HUBERT, PHILIPPE TROUSSEL, et al. "Study of XUV beam splitter flatness for use on a Michelson interferometer." Laser and Particle Beams 22, no. 3 (July 2004): 279–84. http://dx.doi.org/10.1017/s0263034604223114.

Full text

Abstract:

A XUV Michelson interferometer has been developed by LIXAM/CEA/LCFIO and has been tested as a Fourier-transform spectrometer for measurement of X-ray laser line shape. The observed strong deformation of the interference fringes limited the interest of such an interferometer for plasma probing. Because the fringe deformation was coming from a distortion of the beam splitter (5 × 5 mm2open aperture, about 150 nm thick), several parameters of the multilayer deposition used for the beam splitter fabrication have been recently optimized. The flatness has been improved from 80 nm rms obtained by using the ion beam sputtering technique, to 20 nm rms by using the magnetron sputtering technique. Over 3 × 3 mm2, the beam splitter has a flatness better than 4 nm rms.

APA, Harvard, Vancouver, ISO, and other styles

8

Cierpka, K., M. J. Kosch, M. Rietveld, K. Schlegel, and T. Hagfors. "Ion-neutral coupling in the high-latitude F-layer from incoherent scatter and Fabry-Perot interferometer measurements." Annales Geophysicae 18, no. 9 (September 30, 2000): 1145–53. http://dx.doi.org/10.1007/s00585-000-1145-0.

Full text

Abstract:

Abstract. Since the auroral ionosphere provides an important energy sink for the magnetosphere, ionosphere-thermosphere coupling must be investigated when considering the energy budget of the ionosphere-magnetosphere coupling. We present the first Scandinavian ground-based study of high-latitude F-region ion-neutral frictional heating where ion velocity and temperature are measured by the EISCAT incoherent scatter radar as well as neutral wind and temperature being measured simultaneously by a Fabry-Perot interferometer. A geomagnetically active period (Kp = 7– – 5–) and quiet period (Kp = 0+ – 0) were studied. Neglecting the neutral wind can result in errors of frictional heating estimates of 60% or more in the F-layer. About 96% of the local ion temperature enhancement over the neutral temperature is accounted for by ion-neutral frictional heating.Key words: Ionosphere (auroral ionosphere; ionosphere-atmosphere interactions)

APA, Harvard, Vancouver, ISO, and other styles

9

Adams, DP, MB Sinclair, TM Mayer, MJ Vasile, and WC Sweatt. "Optical Interferometer Microscope for Monitoring and Control of Focused Ion Beam Processes." Microscopy and Microanalysis 12, S02 (July 31, 2006): 1280–81. http://dx.doi.org/10.1017/s1431927606065597.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Vaessen, P. H. M., J. M. L. van Engelen, and J. J. Bleize. "Stark-width measurements of argon-ion lines with a Fabry-Pérot interferometer." Journal of Quantitative Spectroscopy and Radiative Transfer 33, no. 1 (January 1985): 51–52. http://dx.doi.org/10.1016/0022-4073(85)90087-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Grydeland, T., J. L. Chau, C. La Hoz, and A. Brekke. "An imaging interferometry capability for the EISCAT Svalbard Radar." Annales Geophysicae 23, no. 1 (January 31, 2005): 221–30. http://dx.doi.org/10.5194/angeo-23-221-2005.

Full text

Abstract:

Abstract. Interferometric imaging (aperture synthesis imaging) is a technique used by radio astronomers to achieve angular resolution that far surpasses what is possible with a single large aperture. A similar technique has been used for radar imaging studies of equatorial ionospheric phenomena at the Jicamarca Radio Observatory. We present plans for adding an interferometric imaging capability to the EISCAT Svalbard Radar (ESR), a capability which will contribute significantly to several areas of active research, including naturally and artificially enhanced ion-acoustic echoes and their detailed relation in space and time to optical phenomena, polar mesospheric summer echoes (PMSE), and meteor studies. Interferometry using the two antennas of the ESR has demonstrated the existence of extremely narrow, field-aligned scattering structures, but having only a single baseline is a severe limitation for such studies. Building additional IS-class antennas at the ESR is not a trivial task. However, the very high scattering levels in enhanced ion-acoustic echoes and PMSE means that a passive receiver antenna of more modest gain should still be capable of detecting these echoes. In this paper we present simulations of what an imaging interferometer will be capable of observing for different antenna configurations and brightness distributions, under ideal conditions, using two different image inversion algorithms. We also discuss different antenna and receiver technologies.

APA, Harvard, Vancouver, ISO, and other styles

12

Zellmer, Lisa, Stanislav Tereschenko, Angelika Brueckner-Foit, and Peter Lehmann. "Investigation of the Three-Dimensional Shape of Slip Bands in Fatigued Dual Phase Steel." Advanced Materials Research 891-892 (March 2014): 482–87. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.482.

Full text

Abstract:

The formation and the three-dimensional shape of slip bands in a fatigued dual phase steel were analyzed with the purpose of understanding the relation between fatigue crack initiation and the topography development on the specimen surface. Fatigue tests with small dog-bone-shaped specimens were conducted under fully reversed axial loading (R = -1) with a constant stress amplitude and were interrupted when the first slip bands occurred and at defined numbers of load cycles, respectively. Subsequently the surface topography of the specimen was investigated with a white light interferometer with hundredfold magnification and high numerical aperture (NA = 0.9) which allows analyzing the surface of individual grains. The results were confirmed by additional atomic force microscopy measurements. Based on this analysis the height, width and length of the slip bands are known at different stages of the fatigue process. The results obtained using white light interferometry and AFM, were checked by cutting individual slip bands with the help of focused ion beam thus revealing the true shape of the slip bands.

APA, Harvard, Vancouver, ISO, and other styles

13

Kafafy, R., and Y. Cao. "Modelling ion propulsion plume interactions with spacecraft in formation flight." Aeronautical Journal 114, no. 1157 (July 2010): 417–26. http://dx.doi.org/10.1017/s0001924000003894.

Full text

Abstract:

Abstract This paper presents a simulation study of ion thruster plume effects on formation flying spacecraft. Two formation flight applications using micro-ion propulsion are considered: an L2-Halo orbit interferometer formation and a LEO micro-satellite formation. Worst case scenarios in both missions have been investigated. We focus our study on thruster configurations resulting in possible indirect plume impingement on satellites outside of the direct impingement zone. Indirect impingement which cannot be predicted except through plasma simulation or in-flight measurements might expose critical spacecraft elements such as optical sensors to a harsh contamination environment. A high-fidelity electrostatic plasma simulation code for parallel computing platforms was used in the study. In our study, we found that using miniature scale ion propulsion in both formation missions creates a very low charge-exchange plasma environment which results in tolerable contamination environment for other spacecraft in the formation.

APA, Harvard, Vancouver, ISO, and other styles

14

Pranevičius, L., S. Tamulevičus, L. Puodžiukynas, and A. Matiukas. "Application of Laser Interferometer Systems for the Study of Ion Interaction with Solids." physica status solidi (a) 96, no. 2 (August 16, 1986): K157—K161. http://dx.doi.org/10.1002/pssa.2210960252.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Sun, J., J. Li, R. R. J. Maier, D. P. Hand, W. N. MacPherson, M. K. Miller, J. M. Ritchie, and X. Luo. "Fabrication of a side aligned optical fibre interferometer by focused ion beam machining." Journal of Micromechanics and Microengineering 23, no. 10 (September 5, 2013): 105005. http://dx.doi.org/10.1088/0960-1317/23/10/105005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Liu, Feng Bin, Hui Ping Li, Yan Cui, Jie Jian Di, Min Qu, and Qi Guo Sun. "Tribological Behavior of Ion Implanted AISI 440C Stainless Steel under Oil Lubricated Condition." Applied Mechanics and Materials 419 (October 2013): 334–40. http://dx.doi.org/10.4028/www.scientific.net/amm.419.334.

Full text

Abstract:

The tribological behaviors of nitrogen and titanium ion implanted AISI 440C stainless steel were studied by using an oscillating ball-on-disk tribometer under oil lubricated condition. The results showed that the ion implantations would significantly decrease the friction coefficient of the samples. To interpret the effect mechanism of the ion implantation on tribological performance, the surface morphology and oil wettability of the ion implanted samples were investigated by using a three-dimensional white interferometer and a contact angle analyzer, respectively. In addition, the surface structures and components of the samples were analyzed by using XRD and XPS techniques. The results indicated that the low friction coefficients of the ion implanted samples can be attributed to the new phases formed on the sample surfaces. For nitrogen ion implanted sample, the metal nitrides, supersaturated interstitial N and some C-O-N compounds appear on the sample surface. For titanium ion implanted sample, apart from TiO2and TiC phases form at the AISI 440C steel surface. Those components increase the surface energy of the AISI 440C steel and are in favor of the formation of the thin oil film.

APA, Harvard, Vancouver, ISO, and other styles

17

Qi, Zhi-mei, Naoki Matsuda, Kiminori Itoh, and Masayuki Murabayashi. "A Highly Selective HF Sensor Based on A Potassium Ion-Exchanged Waveguide Polarimetric Interferometer." Chemistry Letters 30, no. 7 (July 2001): 662–63. http://dx.doi.org/10.1246/cl.2001.662.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Schimpf, A., D. Bucci, M. Nannini, A. Magnaldo, L. Couston, and J. E. Broquin. "Photothermal microfluidic sensor based on an integrated Young interferometer made by ion exchange in glass." Sensors and Actuators B: Chemical 163, no. 1 (March 2012): 29–37. http://dx.doi.org/10.1016/j.snb.2011.11.072.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Benech, P., D. Persegol, and F. Saint Andre. "A glass ion exchanged Mach-Zehnder interferometer to stabilise the frequency of a laser diode." Journal of Physics D: Applied Physics 23, no. 5 (May 14, 1990): 617–19. http://dx.doi.org/10.1088/0022-3727/23/5/023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Yuan, Zheng, Yi Fan Dai, Hao Yu, Xu Hui Xie, and Lin Zhou. "Control of Thermal Effect in Ion Beam Figuring Process Based on Low-Pass Filtering." Applied Mechanics and Materials 120 (October 2011): 360–65. http://dx.doi.org/10.4028/www.scientific.net/amm.120.360.

Full text

Abstract:

During ion beam figuring process, most heat energy is absorbed by optics surface, heating the workpiece surface un-uniformly, called thermal effect. Thermal effect leads to distortion even cracking of the optical figure due to high temperature and temperature gradients, especially for the temperature sensible materials such as BK7, KDP and CaF2. One of the methods on decreasing thermal effect is decreasing total dwelling time and dwelling time gradients. According to the ability of ion beam correction, It is proposed that a new surface error distribution is obtained by filtered by a low pass filter from the initial surface error distribution measured by interferometer, and then it is used to calculate the dwelling time function. It is indicated by simulation that this measured decreases the total dwelling time and dwelling time gradients, reduces the temperature peak and heat stress. At last, a flat surface with the surface accuracy of 0.002λ rms is obtained from the initial surface error of 0.006λ rms, proving that high precision surface can be achieved with the surface after low pass filtering. So it is of great signification for actual application on ion beam figure temperature sensible materials.

APA, Harvard, Vancouver, ISO, and other styles

21

Janik, Monika, Marcin Koba, Anna Celebańska, Wojtek J. Bock, and Mateusz Śmietana. "[INVITED] Sensing properties of micro-cavity in-line Mach-Zehnder interferometer enhanced by reactive ion etching." Optics & Laser Technology 103 (July 2018): 260–66. http://dx.doi.org/10.1016/j.optlastec.2018.01.045.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Datla, R. U. "Measurement of the Tix ion density in aθ-pinch plasma by a laser heterodyne quadrature interferometer." Physical Review A 31, no. 4 (April 1, 1985): 2764–67. http://dx.doi.org/10.1103/physreva.31.2764.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Torrisi, Giuseppe, David Mascali, Lorenzo Neri, Ornella Leonardi, Gino Sorbello, Luigi Celona, Giuseppe Castro, et al. "Microwave frequency sweep interferometer for plasma density measurements in ECR ion sources: Design and preliminary results." Review of Scientific Instruments 87, no. 2 (February 2016): 02B909. http://dx.doi.org/10.1063/1.4933025.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Jiang, Yi, Wenlin Feng, and Xiaozhan Yang. "Aluminium-doped zinc oxide sensing membrane integrated fiber-optic Michelson interferometer for trace fluoride-ion detection." Journal of Physics D: Applied Physics 54, no. 47 (September 2, 2021): 475102. http://dx.doi.org/10.1088/1361-6463/ac203a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Yan, Yuyang, Meiduan Fan, Shuang Zhou, Xiaolan Sun, Longfei Ma, Ruoyu Li, and Alan R. Kost. "Tapered Mach–Zehnder interferometer based on PbS quantum dots modified by polymers for copper ion sensing." Applied Optics 60, no. 16 (May 27, 2021): 4807. http://dx.doi.org/10.1364/ao.425453.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Торопов, М. Н., А. А. Ахсахалян, И. В. Малышев, М. С. Михайленко, А. Е. Пестов, Н. Н. Салащенко, А. К. Чернышов, and Н. И. Чхало. "Линзовый корректор волнового фронта для изучения плоских поверхностей." Журнал технической физики 91, no. 10 (2021): 1583. http://dx.doi.org/10.21883/jtf.2021.10.51374.108-21.

Full text

Abstract:

The method of manufacturing and the results of studies of a lens corrector that converts a spherical diverging front into a plane one and is intended for studying flat surfaces as part of an interferometer with a diffraction comparison wave is described. A feature of the corrector is the use of an aspherical convex surface with a maximum deviation of ∼200 μm from the nearest sphere. The first experimental results are presented, indicating the prospects for using ion-beam processing to improve the quality of the wavefront. After the procedure of ion-beam processing, the aberrations over the entire aperture of the corrector decreased by more than 4 times and amounted to the parameter of the height difference PV = 207 nm (∼λ/3) and RMS = 19.2 nm (∼λ /33). On an area with a diameter of 80%, the aberrations fell to the nanometer level: PV = 65 nm (∼λ/10) and RMS = 8.3 nm (∼λ/76).

APA, Harvard, Vancouver, ISO, and other styles

27

Sullivan, J. M., N. Ivchenko, M. Lockwood, T. Grydeland, E. M. Blixt, and B. S. Lanchester. "Phase calibration of the EISCAT Svalbard Radar interferometer using optical satellite signatures." Annales Geophysicae 24, no. 9 (September 20, 2006): 2419–27. http://dx.doi.org/10.5194/angeo-24-2419-2006.

Full text

Abstract:

Abstract. The link between natural ion-line enhancements in radar spectra and auroral activity has been the subject of recent studies but conclusions have been limited by the spatial and temporal resolution previously available. The next challenge is to use shorter sub-second integration times in combination with interferometric programmes to resolve spatial structure within the main radar beam, and so relate enhanced filaments to individual auroral rays. This paper presents initial studies of a technique, using optical and spectral satellite signatures, to calibrate the received phase of a signal with the position of the scattering source along the interferometric baseline of the EISCAT Svalbard Radar. It is shown that a consistent relationship can be found only if the satellite passage through the phase fringes is adjusted from the passage predicted by optical tracking. This required adjustment is interpreted as being due to the vector between the theoretical focusing points of the two antennae, i.e. the true radar baseline, differing from the baseline obtained by survey between the antenna foot points. A method to obtain a measurement of the true interferometric baseline using multiple satellite passes is outlined.

APA, Harvard, Vancouver, ISO, and other styles

28

Gu, Yong Qiang. "Ion Beam Figuring Fabricate Effect with Different Removal Sizes." Key Engineering Materials 552 (May 2013): 142–46. http://dx.doi.org/10.4028/www.scientific.net/kem.552.142.

Full text

Abstract:

Ion Beam Figure (IBF) is believed to be one of the most effective technics that can fabricate lens with nano or even sub-nano accuracy. For different sizes of IBF removal functions, the correct effects in different spatial frequency range are different. Power Spectral Density (PSD) curve can describe surface errors in full spatial frequency range, so it is a very convenient way to evaluate the quality of lens’ surface. In this paper, firstly, the principles of IBF and PSD are introduced briefly; Secondly, IBF removal functions with sizes from 2 mm to 15 mm are generated. A lens with surface error more than PV value 400nm is simulated with different sizes of IBF removal functions by Lucy-Richardson algorithm. Finally, experiments are done by IBF plant. A lens is fabricated by different sizes of removal functions and the fabricate results are tested by interferometer precisely and calculated to PSD curves. By the comparison of these curves, the IBF fabricate effects with different removal sizes are analyzed, which show that the smaller the removal size, the better the removal effect in higher spatial frequency range, but in the meantime, it will take a much longer time. Also the reasons of the difference between theory simulation and actual fabrication result are taken into account, and several influence factors are analyzed.

APA, Harvard, Vancouver, ISO, and other styles

29

Schütz, G., A. Rembold, A. Pooch, H. Prochel, and A. Stibor. "Effective beam separation schemes for the measurement of the electric Aharonov–Bohm effect in an ion interferometer." Ultramicroscopy 158 (November 2015): 65–73. http://dx.doi.org/10.1016/j.ultramic.2015.06.016.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Datla, R. U. "Measurement of the Ti X ion density in a theta pinch plasma utilizing a laser interferometer (abstract)." Review of Scientific Instruments 56, no. 5 (May 1985): 1072. http://dx.doi.org/10.1063/1.1138226.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Teale, Carson, George Barbastathis, and Martin A. Schmidt. "Vibration Compensated, Scanning White Light Interferometer for In Situ Depth Measurements in a Deep Reactive Ion Etcher." Journal of Microelectromechanical Systems 28, no. 3 (June 2019): 441–46. http://dx.doi.org/10.1109/jmems.2019.2902341.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Helhel, S., A. R. Ellingboe, O. Cerezci, and C. Gaman. "PLASMA DENSITY MEASUREMENTS OF CONFINED CAPACITIVELY COUPLED PLASMA BY MICROWAVE INTERFEROMETER AND ION ENERGY DISTRIBUTION FUNCTION METHODS." International Journal of Infrared and Millimeter Waves 27, no. 11 (May 8, 2007): 1497–515. http://dx.doi.org/10.1007/s10762-006-9149-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Tokuzawa, T., M. Kisaki, K. Nagaoka, K. Tsumori, Y. Ito, K. Ikeda, H. Nakano, M. Osakabe, Y. Takeiri, and O. Kaneko. "Upgraded millimeter-wave interferometer for measuring the electron density during the beam extraction in the negative ion source." Review of Scientific Instruments 87, no. 11 (August 1, 2016): 11E105. http://dx.doi.org/10.1063/1.4959841.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Guo, Chun, and Mingdong Kong. "Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition." Coatings 10, no. 8 (July 23, 2020): 720. http://dx.doi.org/10.3390/coatings10080720.

Full text

Abstract:

Optical and mechanical properties of multilayer coatings depend on the selected layer materials and the deposition technology; therefore, knowledge of the performances of thin films is essential. In the present work, titanium dioxide (TiO2) and silicon dioxide (SiO2) thin films have been prepared by plasma ion-assisted deposition (PIAD). The optical, structural, and mechanical properties of thin films have been investigated using spectrometer/ellipsometer, X-ray diffraction (XRD), atomic force microscopy (AFM), and laser interferometer. The results show that TiO2 film fabricated by PIAD induces a high refractive index, wide optical band gap, amorphous structure, smooth surface, and tensile stress. In the case of SiO2 film, high bias voltage leads to dense structure and compressive stress. As an application, a three-wavelength high reflectance at 632.8, 808, and 1550 nm was optimized and deposited. The dependence of total stress in the multilayer on the substrate temperature was studied as well. In conclusion, it was demonstrated that PIAD is an effective method for the preparation of ultralow stress TiO2/SiO2 multilayer films. The achieved stress was as low as 1.4 MPa. The result could provide guidance to the stress optimization of most optical components without prefiguring, backside coating, and postdeposition treatments.

APA, Harvard, Vancouver, ISO, and other styles

35

Huang, Jiahui, Lijun Li, Yumeng Lv, and Min Li. "The Tribond Bridged Bipyridine Complex-based In-fiber Interferometric Sensor design for Cu2+ Detection." E3S Web of Conferences 213 (2020): 02019. http://dx.doi.org/10.1051/e3sconf/202021302019.

Full text

Abstract:

We report a real-time, lightweight sensor based on in-fiber MZ interferometer coating bipyridine complex L[4-methyl-2, 6-bis(pyridine-3-ylethynyl)aniline](L-ligand) in situ determination of free copper ion at micromolar levels. The sensor is made by fusing a section of thin-core fiber(TCF) in the middle of singlemode fiber(SMF). The L-ligand material is attached to the sensing surface of thin-core fiber to bind free copper ions in liquid environment with high affinity and selectivity. Investigation was carried out that the performance of the sensor is significantly improved with different length. The sensitivity of Cu2+ detection can reach 0.0573 nm/μM (nanometer per micromolar) in linear range of 0μM~25μM and the detection limit is 0.8726μM. This is significantly lower than the allowable level of drinking water.

APA, Harvard, Vancouver, ISO, and other styles

36

Haldoupis, C., A. Bourdillon, A. Kamburelis, G. C. Hussey, and J. A. Koehler. "50 MHz continuous wave interferometer observations of the unstable mid-latitude E-region ionosphere." Annales Geophysicae 21, no. 7 (July 31, 2003): 1589–600. http://dx.doi.org/10.5194/angeo-21-1589-2003.

Full text

Abstract:

Abstract. In this paper we describe the conversion of SESCAT (Sporadic-E SCATter experiment), a bistatic 50 MHz continuous wave (CW) Doppler radar located on the island of Crete, Greece, to a single (east-west) baseline interferometer. The first results show that SESCAT, which provides high quality Doppler spectra and excellent temporal resolution, has its measurement capabilities enhanced significantly when operated as an interferometer, as it can also study short-term dynamics of localized scattering regions within mid-latitude sporadic E-layers. The interferometric observations reveal that the aspect sensitive area viewed by the radar often contains a few zonally located backscatter regions, presumably blobs or patches of unstable metallic ion plasma, which drift across the radar field-of-view with the neutral wind. On average, these active regions of backscatter have mean zonal scales ranging from a few kilometers to several tens of kilometers and drift with westward speeds from ~ 20 m/s to 100 m/s, and occasionally up to 150 m/s. The cross-spectral analysis shows that mid-latitude type 1 echoes occur much more frequently than has been previously assumed and they originate in single and rather localized areas of elevated electric fields. On the other hand, typical bursts of type 2 echoes are often found to result from two adjacent regions in azimuth undergoing the same bulk motion westwards but producing scatter of opposite Doppler polarity, a fact that contradicts the notion of isotropic turbulence to which type 2 echoes are attributed. Finally, quasi-periodic (QP) echoes are observed simply to be due to sequential unstable plasma patches or blobs which traverse across the radar field-of-view, sometimes in a wave-like fashion.Key words. Ionosphere (ionospheric irregularities; mid-latitude ionosphere; plasma waves and instabilities)

APA, Harvard, Vancouver, ISO, and other styles

37

Gu, Bobo, Ming-Jie Yin, A. Ping Zhang, Jin-Wen Qian, and Sailing He. "Fiber-optic metal ion sensor based on thin-core fiber modal interferometer with nanocoating self-assembled via hydrogen bonding." Sensors and Actuators B: Chemical 160, no. 1 (December 2011): 1174–79. http://dx.doi.org/10.1016/j.snb.2011.09.043.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Skeldon, K., and J. Hough. "Measurements of beam geometry fluctuations of typical argon‐ion and Nd:YAG lasers with relevance to laser interferometer gravitational wave detectors." Review of Scientific Instruments 66, no. 4 (April 1995): 2760–62. http://dx.doi.org/10.1063/1.1145622.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Takeiri, Yasuhiko. "Advanced Helical Plasma Research towards a Steady-State Fusion Reactor by Deuterium Experiments in Large Helical Device." Atoms 6, no. 4 (December 8, 2018): 69. http://dx.doi.org/10.3390/atoms6040069.

Full text

Abstract:

The Large Helical Device (LHD) is one of the world’s largest superconducting helical system fusion-experiment devices. Since the start of experiments in 1998, it has expanded its parameter regime. It has also demonstrated world-leading steady-state operation. Based on this progress, the LHD has moved on to the advanced research phase, that is, deuterium experiment, which started in March 2017. During the first deuterium experiment campaign, an ion temperature of 10 keV was achieved. This was a milestone in helical systems research: demonstrating one of the conditions for fusion. All of this progress and increased understanding have provided the basis for designing an LHD-type steady-state helical fusion reactor. Moreover, LHD plasmas have been utilized not only for fusion research, but also for diagnostics development and applications in wide-ranging plasma research. A few examples of such contributions of LHD plasmas (spectroscopic study and the development of a new type of interferometer) are introduced in this paper.

APA, Harvard, Vancouver, ISO, and other styles

40

Heard, D. E., R. A. Brownsword, D. G. Weston, and G. Hancock. "Time-Resolved Pulsed FT-IR Emission Studies of Photochemical Reactions." Applied Spectroscopy 47, no. 9 (September 1993): 1438–45. http://dx.doi.org/10.1366/0003702934067540.

Full text

Abstract:

A time-resolved Fourier transform emission spectrometer, operating in the stop-scan mode, is demonstrated as an inexpensive and versatile instrument for observation of infrared vibrational chemiluminescence. The entire evolution of an emission spectrum is obtained from a single scan of the interferometer, with a spectral and temporal resolution of 2 cm−1 and 10 ns, respectively. Results are presented for a number of radical-radical reactions studied by this technique, where emission from highly excited CO, HF, CO2, and N2O is observed. Measurements include nascent vibrational distributions, quantum yields for branching into different product channels, and bimolecular rate constants for the production and vibrational relaxation of product species. Experiments at low total pressure enable nascent vibrational and rotational distributions to be found for the HF fragment of the CO2 laser photolysis of 1,1-chlorofluoroethylene. In addition, time-resolved spectra of HF, CO, CO2, CF4, and CHF3 are demonstrated for infrared emission observed from a reactive ion plasma etching chamber.

APA, Harvard, Vancouver, ISO, and other styles

41

Friederich, F., T. von Clarmann, B. Funke, H. Nieder, J. Orphal, M. Sinnhuber, G. P. Stiller, and J. M. Wissing. "Lifetime and production rate of NO<sub>x</sub> in the upper stratosphere and lower mesosphere in the polar spring/summer after the solar proton event in October–November 2003." Atmospheric Chemistry and Physics 13, no. 5 (March 5, 2013): 2531–39. http://dx.doi.org/10.5194/acp-13-2531-2013.

Full text

Abstract:

Abstract. We present altitude-dependent lifetimes of NOx, determined with MIPAS/ENVISAT (the Michelson Interferometer for Passive Atmospheric Sounding/the European Environment Satellite), for the Southern polar region after the solar proton event in October–November 2003. Between 50° S and 90° S and decreasing in altitude they range from about two days at 64 km to about 20 days at 44 km. The lifetimes are controlled by transport, mixing and photochemistry. We infer estimates of dynamical lifetimes by comparison of the observed decay to photochemical lifetimes calculated with the SLIMCAT 3-D Model. Photochemical loss contributes to the observed NOx depletion by 0.1% at 44 km, increasing with altitude to 45% at 64 km. In addition, we show the correlation of modelled ionization rates and observed NOx densities under consideration of the determined lifetimes of NOx, and calculate altitude-dependent effective production rates of NOx due to ionization. For that we compare ionization rates of the AIMOS data base with the MIPAS measurements from 15 October–31 December 2003. We derive effective NOx-production rates to be applied to the AIMOS ionization rates which range from about 0.2 NOx-molecules per ion pair at 44 km to 0.7 NOx-molecules per ion pair at 62 km. These effective production rates are considerably lower than predicted by box model simulations which could hint at an overestimation of the modelled ionization rates.

APA, Harvard, Vancouver, ISO, and other styles

42

Aruliah, A. L., E. M. Griffin, H. C. I. Yiu, I. McWhirter, and A. Charalambous. "SCANDI – an all-sky Doppler imager for studies of thermospheric spatial structure." Annales Geophysicae 28, no. 2 (February 15, 2010): 549–67. http://dx.doi.org/10.5194/angeo-28-549-2010.

Full text

Abstract:

Abstract. A new all-sky Fabry-Perot Interferometer called the Scanning Doppler Imager (SCANDI) was built and installed at Longyearbyen in December 2006. Observations have been made of the Doppler shifts and Doppler broadening of the 630 nm airglow and aurora, from which upper thermospheric winds and temperatures are calculated. SCANDI allows measurements over a field-of-view (FOV) with a horizontal radius of nearly 600 km for observations at an altitude of 250 km using a time resolution of 8 min. The instrument provides the ability to observe thermospheric spatial structure within a FOV which overlaps that of the EISCAT Svalbard radar and CUTLASS SuperDARN radars. Coordinating with these instruments provides an important opportunity for studying ion-neutral coupling. The all-sky image is divided into several sectors to provide a horizontal spatial resolution of between 100–300 km. This is a powerful extension in observational capability but requires careful calibration and data analysis, as described here. Two observation modes were used: a fixed and a scanning etalon gap. SCANDI results are corroborated using the Longyearbyen single look direction FPI, and ESR measurements of the ion temperatures. The data show thermospheric temperature gradients of a few Kelvins per kilometre, and a great deal of meso-scale variability on spatial scales of several tens of kilometres.

APA, Harvard, Vancouver, ISO, and other styles

43

Mizuno, Yosuke, Christian M. Fromm, Ziri Younsi, Oliver Porth, Hector Olivares, and Luciano Rezzolla. "Comparison of the ion-to-electron temperature ratio prescription: GRMHD simulations with electron thermodynamics." Monthly Notices of the Royal Astronomical Society 506, no. 1 (June 21, 2021): 741–58. http://dx.doi.org/10.1093/mnras/stab1753.

Full text

Abstract:

ABSTRACT The Event Horizon Telescope (EHT) collaboration, an Earth-size sub-millimetre radio interferometer, recently captured the first images of the central supermassive black hole in M87. These images were interpreted as gravitationally lensed synchrotron emission from hot plasma orbiting around the black hole. In the accretion flows around low-luminosity active galactic nuclei such as M87, electrons and ions are not in thermal equilibrium. Therefore, the electron temperature, which is important for the thermal synchrotron radiation at EHT frequencies of 230 GHz, is not independently determined. In this work, we investigate the commonly used parametrized ion-to-electron temperature ratio prescription, the so-called R−β model, considering images at 230 GHz by comparing with electron-heating prescriptions obtained from general-relativistic magnetohydrodynamical (GRMHD) simulations of magnetized accretion flows in a Magnetically Arrested Disc (MAD) regime with different recipes for the electron thermodynamics. When comparing images at 230 GHz, we find a very good match between images produced with the R−β prescription and those produced with the turbulent- and magnetic reconnection-heating prescriptions. Indeed, this match is on average even better than that obtained when comparing the set of images built with the R−β prescription with either a randomly chosen image or with a time-averaged one. From this comparative study of different physical aspects, which include the image, visibilities, broad-band spectra, and light curves, we conclude that, within the context of images at 230 GHz relative to MAD accretion flows around supermassive black holes, the commonly used and simple R−β model is able to reproduce well the various and more complex electron-heating prescriptions considered here.

APA, Harvard, Vancouver, ISO, and other styles

44

Zhang, Zhi Yu, Xu Yang, and Li Gong Zheng. "Fabrication of Computer Generated Hologram for Aspheric Surface Measurement." Advanced Materials Research 1136 (January 2016): 620–23. http://dx.doi.org/10.4028/www.scientific.net/amr.1136.620.

Full text

Abstract:

High-precision aspheric surfaces are generally measured using interferometer with a computer-generated holograms (CGH), which has a wavy line pattern fabricated onto a glass substrate. CGH patterns are generally made using lithographic techniques that was developed for semiconductor industry. Patterns can be subsequently etched into glass substrate using reactive ion or chemical etching. The accuracy of the drawn pattern on a CGH decides the accuracy of the measurement. Draw pattern error mainly includes the line-width deviation and its position error. In this paper, the influences of defocus of drawing laser and the wet-etching processes on the line-width were firstly investigated. On the other hand, the position error under different line-width was obtained by analyzing the relationship of line-width error and the position error. Based on the above-obtained results, a CGH having a diameter of 80 mm and the minimum line-width of 1.8 μm was successfully fabricated. Testing results showed that the wavefront error was only 3.79 nm, significantly higher than the commercial-available ones. The fabricated CGH is expected to use in the high-precision measurement of asphercal surfaces.

APA, Harvard, Vancouver, ISO, and other styles

45

Oyama, S., S. Nozawa, S. C. Buchert, M. Ishii, S. Watari, E. Sagawa, W. Kofman, J. Lilensten, and R. Fujii. "Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region." Annales Geophysicae 18, no. 9 (September 30, 2000): 1154–63. http://dx.doi.org/10.1007/s00585-000-1154-z.

Full text

Abstract:

Abstract. The field-aligned neutral oscillations in the F-region (altitudes between 165 and 275 km) were compared using data obtained simultaneously with two independent instruments: the European Incoherent Scatter (EISCAT) UHF radar and a scanning Fabry-Perot interferometer (FPI). During the night of February 8, 1997, simultaneous observations with these instruments were conducted at Tromsø, Norway. Theoretically, the field-aligned neutral wind velocity can be obtained from the field-aligned ion velocity and by diffusion and ambipolar diffusion velocities. We thus derived field-aligned neutral wind velocities from the plasma velocities in EISCAT radar data. They were compared with those observed with the FPI (λ=630.0 nm), which are assumed to be weighted height averages of the actual neutral wind. The weighting function is the normalized height dependent emission rate. We used two model weighting functions to derive the neutral wind from EISCAT data. One was that the neutral wind velocity observed with the FPI is velocity integrated over the entire emission layer and multiplied by the theoretical normalized emission rate. The other was that the neutral wind velocity observed with the FPI corresponds to the velocity only around an altitude where the emission rate has a peak. Differences between the two methods were identified, but not completely clarified. However, the neutral wind velocities from both instruments had peak-to-peak correspondences at oscillation periods of about 10–40 min, shorter than that for the momentum transfer from ions to neutrals, but longer than from neutrals to ions. The synchronizing motions in the neutral wind velocities suggest that the momentum transfer from neutrals to ions was thought to be dominant for the observed field-aligned oscillations rather than the transfer from ions to neutrals. It is concluded that during the observation, the plasma oscillations observed with the EISCAT radar at different altitudes in the F-region are thought to be due to the motion of neutrals.Key words: Ionosphere (Ionosphere–atmosphere interactions) – Meteorology and atmospheric dynamics (thermospheric dynamics; waves and tides)

APA, Harvard, Vancouver, ISO, and other styles

46

Slamani, Mohamed, Ahmed Joubair, and Ilian A. Bonev. "A comparative evaluation of three industrial robots using three reference measuring techniques." Industrial Robot: An International Journal 42, no. 6 (October 19, 2015): 572–85. http://dx.doi.org/10.1108/ir-05-2015-0088.

Full text

Abstract:

Purpose – The purpose of this paper is to present a technique for assessing and comparing the static and dynamic performance of three different models of small six-axis industrial robots using a Renishaw XL80 laser interferometer system, a FARO ION laser tracker and a Renishaw QC20-W telescoping ballbar. Design/methodology/approach – Specific test methods are proposed in this work, and each robot has been measured in a similar area of its working envelope. The laser interferometer measurement instrument is used to assess the static positioning performance along three linear and orthogonal paths. The laser tracker is used to assess the contouring performance at different tool center point (TCP) speeds along a triangular tool path, whereas the telescoping ballbar is used to assess the dynamic positioning performance for circular paths at different TCP speeds and trajectory radii. Findings – It is found that the tested robots behave differently, and that the static accuracy of these non-calibrated robots varies between 0.5 and 2.3 mm. On the other hand, results show that these three robots can provide acceptable corner tracking at low TCP speeds. However, a significant overshoot at the corner is observed at high TCP speed for all the robots tested. It was also found that the smallest increment of Cartesian displacement (Cartesian resolution) that can be taken by the tested robots is approximately 50 μm. Practical implications – The technique used in this paper allows extremely accurate diagnosis of the robot performance, which makes it possible for the robot user to determine whether the robot is in good or bad condition. It can also help the decision-maker to select the most suitable industrial robot to achieve the desired task with minimum cost and specific application ability. Originality/value – This paper proposed a new method based on the performance verification approach for solving the robot selection problem for flexible manufacturing systems. Furthermore, despite their importance, bidirectional repeatability and Cartesian resolution are never specified by the manufacturers of industrial robots nor are they described in the ISO 9283:1998 guide, and they are rarely the object of performance assessments. In this work, specific tests are performed to check and quantify the bidirectional repeatability and the Cartesian resolution of each robot.

APA, Harvard, Vancouver, ISO, and other styles

47

Aruliah, A. L., E. M. Griffin, A. D. Aylward, E. A. K. Ford, M. J. Kosch, C. J. Davis, V. S. C. Howells, S. E. Pryse, H. R. Middleton, and J. Jussila. "First direct evidence of meso-scale variability on ion-neutral dynamics using co-located tristatic FPIs and EISCAT radar in Northern Scandinavia." Annales Geophysicae 23, no. 1 (January 31, 2005): 147–62. http://dx.doi.org/10.5194/angeo-23-147-2005.

Full text

Abstract:

Abstract. This paper presents the first direct empirical evidence that mesoscale variations in ion velocities must be taken into consideration when calculating Joule heating and relating it to changes in ion temperatures and momentum transfer to the neutral gas. The data come from the first tristatic Fabry-Perot Interferometer (FPI) measurements of the neutral atmosphere co-located with tristatic measurements of the ionosphere made by the European Incoherent Scatter (EISCAT) radar which were carried out during the nights of 27-28 February 2003 and 28 February until 1 March 2003. Tristatic measurements mean that there are no assumptions of uniform wind fields and ion drifts, nor zero vertical winds. The independent, tristatic, thermospheric measurements presented here should provide unambiguous vector wind information, and hence reduce the need to supplement observations with information obtained from models of the neutral atmosphere, or with estimates of neutral parameters derived from ionospheric measurements. These new data can also test the assumptions used in models and in ion-neutral interactions. The FPIs are located close to the 3 radars of the EISCAT configuration in northern Scandinavia, which is a region well covered by a network of complementary instruments. These provide a larger scale context within which to interpret our observations of mesoscale variations on the scales of tens of kilometres spatially and minutes temporally. Initial studies indicate that the thermosphere is more dynamic and responsive to ionospheric forcing than expected. Calculations using the tristatic volume measurements show that the magnitude of the neutral wind dynamo contribution was on average 29% of Joule heating during the first night of observation. At times it either enhanced or reduced the effective electric field by up to several tens of percent. The tristatic experiment also presents the first validation of absolute temperature measurements from a common volume observed by independently calibrated FPIs. Comparison of EISCAT ion temperatures at an altitude of 240km with FPI neutral temperatures show that Ti was around 200K below Tn for nearly 3h on the first night during a period of strong geomagnetic activity. This is inconsistent with energy transfer. Comparison with FPI temperatures from surrounding regions indicate that it could not be accounted for by height variations. Indeed, these first results seem to indicate that the 630-nm emission did not stray too far from 240km. There were also apparent drops in Te at the same time as the anomalous Ti values which are energetically implausible. Incorrect assumptions of composition or non-Maxwellian spectra are likely to be the problem.

APA, Harvard, Vancouver, ISO, and other styles

48

HOROWITZ, C. J. "MULTI-MESSENGER OBSERVATIONS OF NEUTRON-RICH MATTER." International Journal of Modern Physics E 20, no. 10 (October 2011): 2077–100. http://dx.doi.org/10.1142/s0218301311020332.

Full text

Abstract:

At very high densities, electrons react with protons to form neutron-rich matter. This material is central to many fundamental questions in nuclear physics and astrophysics. Moreover, neutron-rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that uses parity violating electron scattering to measure the neutron radius in 208Pb. This has important implications for neutron stars and their crusts. We discuss X-ray observations of neutron star radii. These also have important implications for neutron-rich matter. Gravitational waves (GW) open a new window on neutron-rich matter. They come from sources such as neutron star mergers, rotating neutron star mountains, and collective r-mode oscillations. Using large scale molecular dynamics simulations, we find neutron star crust to be very strong. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. Finally, neutrinos from core collapse supernovae (SN) provide another, qualitatively different probe of neutron-rich matter. Neutrinos escape from the surface of last scattering known as the neutrino-sphere. This is a low density warm gas of neutron-rich matter. Neutrino-sphere conditions can be simulated in the laboratory with heavy ion collisions. Observations of neutrinos can probe nucleosyntheses in SN. Simulations of SN depend on the equation of state (EOS) of neutron-rich matter. We discuss a new EOS based on virial and relativistic mean field calculations. We believe that combing astronomical observations using photons, GW, and neutrinos, with laboratory experiments on nuclei, heavy ion collisions, and radioactive beams will fundamentally advance our knowledge of compact objects in the heavens, the dense phases of QCD, the origin of the elements, and of neutron-rich matter.

APA, Harvard, Vancouver, ISO, and other styles

49

Griffin, E. M., A. L. Aruliah, I. McWhirter, H. C. I. Yiu, A. Charalambous, and I. McCrea. "Upper thermospheric neutral wind and temperature measurements from an extended spatial field." Annales Geophysicae 26, no. 9 (September 12, 2008): 2649–55. http://dx.doi.org/10.5194/angeo-26-2649-2008.

Full text

Abstract:

Abstract. First results are presented from a Scanning Doppler Imager (SCANDI) installed at the Nordlysstasjonen optical observatory near Longyearbyen, Svalbard (78.2° N, 15.8° E). Observations of the atomic oxygen 630 nm red line emission, originating in the upper thermosphere at around 250 km, have been used to determine neutral winds and temperatures from multiple zones within an extended spatial field. The instrument utilises all-sky optics to achieve multiple simultaneous measurements, compared to the standard Fabry-Perot Interferometer (FPI) procedure of separate line-of-sight samples within a sequence of narrow angle look directions. SCANDI is colocated with such a standard FPI and comparison of neutral wind velocities between the instruments on the night of 15 March 2007 has revealed detailed and consistent structure in the wind field. Southward meridional wind enhancements of several hundred m/s are observed simultaneously with both instruments, revealing structure on scales not currently considered in thermospheric general circulation models (GCMs). The data from this night also demonstrate the influence of discrete auroral events on thermospheric behaviour. High intensities observed by SCANDI in the presence of auroral arcs coincide with a drop in measured neutral temperatures. This is interpreted as a result of the effective altitude of the 630 nm emission being lowered under conditions of soft auroral precipitation. The optical instruments as a consequence sample a region of lower temperature. This effect has been observed previously with lower thermospheric atomic oxygen emissions at 557.7 nm. The EISCAT Svalbard Radar (ESR) provides ion temperatures and electron densities for the night which confirm the influence of precipitation and heating during the auroral events. The minima of ion temperatures through the pre-midnight period provide a good match to the neutral temperatures measured with SCANDI, and to the colocated FPI temperatures.

APA, Harvard, Vancouver, ISO, and other styles

50

Crickmore, R. I. "Mean thermospheric winds observed from Halley, Antarctica." Annales Geophysicae 12, no. 10/11 (August 31, 1994): 1101–13. http://dx.doi.org/10.1007/s00585-994-1101-5.

Full text

Abstract:

Abstract. Thermospheric winds on a total of 237 nights have been studied for the effects due to geomagnetic activity, solar flux, and season. The observations have been made from 1988 to 1992 by a Fabry-Perot interferometer (FPI) operating at Halley (75.5°S, 26.6°W), Antarctica. This is the first statistical study of thermospheric winds near the southern auroral zone. The main factor affecting the wind velocities is the geomagnetic activity. Increases in activity cause an increase in the maximum equatorward wind, and cause the zonal wind in the evening to become more westward. Smaller changes in the mean wind occur with variations in season and solar flux. The small variation with solar flux is more akin to the situation found at mid-latitudes than at high latitudes. Since the geomagnetic latitude of Halley is only 61°, it suggests that the variability of the wind with solar flux may depend more on geomagnetic than geographic latitude. These observations are in good agreement with the empirical Horizontal Wind Model (HWM90). However, comparisons with predictions of the Vector Spherical Harmonic Model (VSH) show that for low geomagnetic activity the predicted phases of the two components of the wind closely resemble the observations but the modelled amplitudes are too small by a factor of two. At high geomagnetic activity the major differences are that modelled zonal velocity is too westward in the evening and too eastward after 04 UT. The modelled ion densities at the F-region peak are a factor of up to 9 too large, whilst the predicted mean value and diurnal variation of the altitude of the peak are significantly lower than those observed. It is suggested that these differences result from the ion loss rate being too low, and an inaccurate model of the magnetic field.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Ion interferometer'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles