Dissertations / Theses on the topic 'Beam Position Monitor (BPM)'

The High Radiation to Materials facility employs a high intensity pulsed beam imposing several challenges on the beam position monitors. Diamond has been shown to be a resilient material with its radiation hardness and mechanical strength, while it is also simple due to its wide bandgap removing the need for doping. A new type of diamond based beam position monitor has been constructed, which includes a hole in the center of the diamond where the majority of the beam is intended to pass through. This increases the longevity of the detectors as well as allowing them to be used for high intensity beams. The purpose of this thesis is to evaluate the performance of the detectors in the High Radiation to Materials facility for various beam parameters, involving differences in position, size, bunch intensity and bunch number. A prestudy consisting of calibration of the detectors using single incident particles is also presented. The detectors are shown to work as intended after a recalibration of the algorithm, albeit with a slightly lower precision than requested, giving a promising new beam position monitoring system. They work for the full intensity range and a single bunch resolution is achieved. Functionality is also shown with backscattering from dense targets.

L’exploration d’une nouvelle physique à l’échelle d’énergie des « Tera electron Volt » (TeV) nécessite de collisionner des leptons dans de grands accélérateurs linéaires à grande luminosité. Ces collisionneurs linéaires requiert une taille de faisceau à l’echelle nanométrique au Point d’Interaction (IP).Parmi les multiples effets participant à la degradation de la luminosité, la correction de la chromaticité, l’effet du rayonnement synchrotronique et la correction des erreurs dans la ligne sont parmi les trois effets à maîtriser afin de réduire la taille du faisceau dans la Section Finale de Focalisation (FFS).Cette these propose un nouveau schéma de correction de la chromaticitè que l’on appelera “non-entrelacé”, appliqué ici au projet CLIC. Lors de l’implementation de cette nouvelle methode, il a été mis en evidence que le probléme principal est la dispersion de deuxième ordre au Doublet Final (FD), qui traverse un sextupole utilisé pour annuler les composantes géometriques restantes.L’effet du rayonnement peut être evalué par méthode de tracking des particules ou par des approximations analytiques. Afin d’inclure ces effets du rayonnement et les paramétres optiques de la ligne pendant la conception et le processus d’optimisation, l’effet Oide et le rayonnement dû aux aimants dipolaires ont été etudiés.Le résultat analytique du rayonnement synchrotronique dans les aimants dipolaires fut generalisé dans les cas avec alpha et dispersion non-nulles à l’IP. Cette généralisation est utilisée pour améliorer le code de simulation PLACET.Le rayonnement dans les aimants quadripolaires finaux imposent une limite à la taille verticale minimale du faiceau, connu comme l’effet Oide. Celui-ci est uniquement important à 3 TeV, donc deux possibilités sont explorées pour atténuer sa contribution dans la taille du faisceau : doubler la longueur et réduire le gradient du dernièr quadripole (QD0), ou integrer une paire d’aimants octupolaires, un en amont et un en aval du QD0.Une partie des exigences du FFS pour les nouveaux collisionneurs linéaire à leptons est testée expérimentalement dans l’« Accelerator Test Facility » (ATF). La réduction de la taille du faisceau d’électrons en utilisant le schéma local de correction de la chromaticité est explorée dans une extension de la ligne originale, appellé ATF2, oú deux buts furent fixés : atteindre 37 nm de taille verticale du faisceau à l’IP, et stabiliser de l’ordre du nanomètre la position verticale du faisceau à l’IP. Depuis 2014, une taille de 44 nm avec un nombre de particules d’environ 0.1 × 10^10 par paquet est atteint de manière regulière.Des cavités radio-frequence seront utilisées pour la stabilisation du faisceau, et également pour détecter le déplacement/les fluctuations du faisceau au dehors la marge tolerable pour le systéme de mesure, ainsi que des erreurs non detectées dans l’optique.Un set de trois cavités furent installées et sont utilisées pour mesurer la trajectoire du faiceau dans la région de l’IP, fournissant ainsi des informations pour reconstruire la position et l’angle à l’IP. Les specifications pour l’optique nominale d’ATF2, i.e. 1 nm de résolution sur 10 μm de gamme dynamique à un nombre de particules de 1.0 × 10^10 par paquet, n’ont pas encore été atteint.La meilleur résolution atteinte jusqu’ici correspond à 50 nm pour 0.4 × 10^10 particules par paquet, où le bruit de l’éléctronique impose une limite de 10 nm par cavité sur la résolution. La gamme dynamique est de 10 μm à 0.4 × 10^10 particules par paquet et 10 dB d’attenuation du signal des cavités, nécéssitant de mettre l’électronique à niveau. Le test du système d’asservissement pour stabiliser le faisceau a atteint une réduction de la fluctuation jusqu’a 67 nm, compatible avec la résolution des cavités
The exploration of new physics in the “Tera electron-Volt” (TeV) scale with precision measurements requires lepton colliders providing high luminosities to obtain enough statistics for the particle interaction analysis. In order to achieve design luminosity values, linear colliders feature nanometer beam spot sizes at the Interaction Point (IP).Three main issues to achieve the beam size demagnification in the Final Focus Section (FFS) of the accelerator are the chromaticity correction, the synchrotron radiation effects and the correction of the lattice errors.This thesis considers two aspects for linear colliders: push the limits of linear colliders design, in particular the chromaticity correction and the radiation effects at 3 TeV, and the instrumentation and experimental work on beam stabilization in a test facility.A new chromaticity correction scheme, called non-interleaved, is proposed to the local and non-local chromaticity corrections for CLIC. This lattice is designed and diagnosed, where the main issue in the current state of lattice design is the non-zero second order dispersion in the Final Doublet (FD) region where a strong sextupole is used to correct the remaining geometrical components.The radiation effect can be evaluated by tracking particles through the lattice or by analytical approximations during the design stage of the lattices. In order to include both, radiation and optic parameters, during the design optimization process, two particular radiation phenomena are reviewed: the Oide effect and the radiation caused by bending magnets .The analytical result of the radiation in bending magnets in was generalized to the case with non-zero alpha and non-zero dispersion at the IP, required during the design and luminosity optimization process. The closed solution for one dipole and one dipole with a drift is compared with the tracking code PLACET, resulting in the improvement of the tracking code results.The Oide effect sets a limit on the vertical beamsize due to the radiation in the final quadrupole. Only for CLIC 3 TeV this limit is significant, therefore two possibilities are explored to mitigate its contribution to beam size: double the length and reduce the QD0 gradient, or the integration of a pair of octupoles before and after QD0.Part of the requirements of the FFS for new linear accelerators are tested in The Accelerator Test Facility (ATF). The beam size reduction using the local chromaticity correction is explored by an extension of the original design, called ATF2 with two goals: achieve 37 nm of vertical beam size at the IP, and the stabilization of the IP beam position at the level of few nanometres. Since 2014 beam size of 44 nm are achieved as a regular basis at charges of about 0.1 × 10^10 particules per bunch.A set of three cavities (IPA, IPB and IPC), two upstream and one downstream of the nominal IP and on top of separate blocks of piezo-electric movers, were installed and are used to measure the beam trajectory in the IP region, thus providing enough information to reconstruct the bunch position and angle at the IP. These will be used to for beam stabilization and could detect beam drift/jitter beyond the tolerable margin and undetected optics mismatch affecting the beam size measurements. The specifications required of 1 nm resolution over 10 μm dynamic range at 1.0 × 10 10 particules per bunch with the ATF2 nominal optics have not been yet achieved.The minimum resolution achieved is just below 50 nm at 0.4 × 10^10 particules per bunch with a set of electronics impossing a noise limit on resolution of 10 nm per cavity. The dynamic range is 10 μm at 10 dB attenuation and 0.4 × 10^10 particules per bunch, indicating the need to upgrade theelectronics. The integration to the ATF tuning instruments is ongoing. Nonetheless, feedback has been tested resulting in reduction of beam jitterdown to 67 nm, compatible with resolution

LBA es una fuente de luz de sincrotrón de tercera generación, en funcionamiento desde 2011, al servicio de una comunidad científica e industrial nacional e internacional. Varios laboratorios (lineas de luz) explotan la radiación electromagnética hasta los rayos X, para una amplia gama de experimentos físicos, químicos, y biológicos. Con el fin de conseguir un elevado flujo de radiación y pequeña divergencia, el anillo de almacenamiento de electrones emplea imanes intensos distribuidos en una malla optimizada para dar forma a las características del haz de electrones. Por otra parte, los imanes pueden tener varios errores qué afectan, de forma perjudicial, a las características del haz de electrones tales como el tamaño, la divergencia o el tiempo de vida. Los errores pueden ser debidos a tolerancias de fabricación mecánica, histéresis magnética, variaciones térmicas o desalineaciones mecánicas. El delicado "equilibrio magnético" requerido para operar éstas fuentes de luz no podría cumplirse sin una herramienta para medir y corregir la malla magnética. Para este propósito, han sido desarrollados procedimientos que utilizan el haz almacenado como sonda para inspeccionar los campos magnéticos reales. Entre las distintas técnicas, las medidas "vuelta-vuelta" permiten construir un modelo de los errores magnéticos a través de la observación del movimiento transversal del haz de electrones vuelta tras vuelta. El objetivo principal de esta tesis doctoral es implementar por primera vez la técnica vuelta-vuelta en ALBA a fin de establecer las capacidades de las medidas de errores magneticos lineales y no lineales. Un primer conjunto de experimentos está dedicado a la caracterización de los errores lineales que muestra un nivel de acuerdo (beta-beat < 2%) comparable con el de otros métodos basados en medidas de órbita cerrada. Pruebas adicionales para establecer la máxima sensibilidad a pequeñas variaciónes de las funciones ópticas se has obtenido manipulando elementos magnéticos y midiendo las variaciones ópticas producidas. La técnica vuelta-vuelta se ha aplicado también a la caracterización del acoplamiento de betatrón en ALBA. Se ha observado un alto grado de precisión en la localización de la fuente de error, y sólo un 10% de desacuerdo entre las medidas de la fuerza de la fuente de acoplamiento y las predicciones teóricas. Una prueba similar también se ha llevado a cabo para las familias de sextupolos, utilizando uno shunt resistivo para cambiar de manera individual la corriente de excitación de un sextupolo. La capacidad de localizar la posición del error sextupolar ha sido demostrada con éxito. Los experimentos mostraron cómo la técnica vuelta-vuelta destaca por sensibilidad a pequeñas variaciones de las funciones ópticas. Esto hizo posible, por primera vez en una fuente de luz de sincrotrón, la aplicación de la técnica vuelta-vuelta a la medida de fuentes localizadas de impedancia transversal. El experimento, llevado a cabo en ALBA, ha permitido distinguir y caracterizar el efecto de desfocalización producido por diferentes fuentes de impedancia transversal, incluyendo elementos como el scraper, cámara de vacío de los imanes de inyección o de un ondulador y la cámara de vacío estándar. La buena concordancia entre medidas y modelo de impedancia transversal, basado en el cálculo analítico de la pared resistiva y en la simulación del código GdfidL de la impedancia geométrica, ha confirmado que la técnica vuelta-vuelta es una herramienta de diagnóstico muy sensible. Asimismo, se ha demostrado que fuentes de impedancia más pequeñas pueden ser caracterizadas adecuadamente variando la óptica de la máquina de modo de obtener una ampliación del efecto de desfocalización inducido. Este método se ha utilizado para caracterizar impedancias tan pequeñas como el de un "in vacuum undulator" de ALBA.
ALBA is a third generation light source, commissioned in 2011, serving a national and international scientific and industrial community. It provides synchrotron radiation up to the hard x-rays as a tool to multiple laboratories (beamlines) for a wide range of physical, chemical, and biological experiments. In order to achieve the required radiation flux and small divergence, the electron storage ring employs an optimized design where strong magnets are combined in a rather complex lattice to properly shape the characteristics of the electron beam. However, the lattice can have several errors, which detrimentally affect the electron beam characteristics such as size, divergence, or lifetime. Unavoidable lattice errors can be due to manufacturing mechanical tolerances, magnet hysteresis, thermal variations and/or mechanical misalignments. The delicate "magnetic equilibrium" required to operate such light sources could be hardly met without a tool to measure and correct the actual magnetic lattice. For this purpose beam-based methods, where the stored beam serves as probe to inspect the lattice, have been developed. Among the various techniques, turn-by-turn measurements allow to asses a lattice error model by sampling turn after turn the transverse motion of the beam. The main purpose of this PhD work is to implement for the first time the turn-by-turn technique at ALBA in order to establish the capabilities of the measurements in the context of linear and non-linear lattice errors. A first set of experiments was dedicated to the characterization of the linear lattice, showing a level of agreement (beta-beat < 2%), comparable to what observed with other methods based on the closed orbit technique. Further tests to establish the ultimate sensitivity to small optical functions variations were obtained by manipulating single lattice elements and measuring the resulting optics variations. Turn-by-turn technique has been applied to the characterization of coupling in the ALBA light source. The ability of turn-by-turn to correctly localize a single source of coupling was challenged by introducing in the storage ring lattice a controlled coupling source. A high degree of precision was observed in localizing the error source, and only a 10% disagreement between measurements and theoretical predictions on the coupling source strength was observed. A similar test was also carried out for the sextupole families using a resistive shunt to change the excitation current of a single element. The ability to localize the sextupolar error position in the lattice was successfully demonstrated. The experiments showed how the turn-by-turn acquisitions shine as for sensibility, enabling the detection of very small variations of the optics function. This made it possible to apply the turn-by-turn technique, for the first time in a light source, to the measurement of localized transverse impedance sources. The experiment, carried out in the ALBA storage ring, led to the characterization of the individual defocusing effects produced by different transverse impedance sources, including elements like scraper, injection zone, in-vacuum undulator and standard vacuum beam pipe. The good agreement between the measurements and the transverse impedance model based on analytical calculation of the resistive wall and GdfidL simulation of the geometrical impedance confirmed that the turn-by-turn technique is a valid diagnostic tool to carry out very sensitive and non-intrusive optics measurements. Furthermore it has been shown how the smaller impedance sources can still be properly characterized by manipulating the machine optics in order to obtain a magnification of the induced defocusing kick. This method has been used to characterize impedances as small as the one of the ALBA IVUs.

Beam position monitors are required in all accelerators for the measurement and optimization of the beam parameters. Cavity beam position monitors (CBPM) offer the possibility of measurement of beam centroid positions at the nanometer scale. These devices can be and typically are used at electron accelerator facilities, both existing light sources and test facilities proposed for future linear colliders, such as the International Linear Collider (ILC) and Compact Linear Collider (CLIC). The requirements for the CLIC main linac are to measure the beam position using approximately 5000 beam position monitors (BPM) with 50 nm resolution, at every 50 ns. The high resolution, enormous scale of the system and the small bunch separation of 0.5 ns present many challenges and demand innovative approaches for the design and operation of the CBPM system. A cylindrical cavity BPM system has been designed in collaboration with the Diamond Light Source, in the C-Band frequency region. The design ideas, which will be beneficial to CLIC BPM and other designs, such as the deliberate separation of modes coupled to the x and y position measurements and the cavity operation without mechanical tuning are tested in the design. The major resonance modes of the cavity are simulated using Eigenmode simulation. The coupling and isolation characteristics are simulated using S-parameter simulations, while the beam coupling is studied through time domain simulations. Four cavities were fabricated according to the design discussed in this this. Their coupling and isolation were tested through S-parameter measurements. The dipole modes are separated by more than 5 MHz in frequency. The values of the quality factors were measured using the impedance method. The field orientation of the dipole and quadrupole modes were measured using the bead-pull perturbation technique and found to be rotated by 12° and 30 from x-axis respectively. The initial beam studies were carried out at the Diamond Light Source and at the ATF2 beam line, and are presented in this thesis. The techniques for position determination of temporally closely spaced bunches are studied. A method was developed to remove the errors in the position determination, due to the overlap of the signals from the previous bunches, by subtracting the decayed phasors from the previous bunch. The method is applied to the signals from the CBPM system on the ATF2 beam line, in the two and three bunch mode operation. The overestimation in position determination of the second bunch is reduced from more than 67% to less than 2%. Position resolution of better than 3 um is demonstrated for the second bunch. The observed phase difference between the consecutive bunches is studied for different bunch spacing. The performance of the code is verified against simulated data.

The interlock Beam Position Monitor (BPM) system in the Large Hadron Collider(LHC) is responsible for monitoring the particle beam position at the point of thebeam dump kicker magnets and is part of the machine protection system. Thecurrent interlock BPM system has some limitations and because of this, an upgradeproject has been initiated. This master thesis describes the development of theanalog front end electronics of this system, consisting mainly of two parts: A delayline based microwave filter and a high isolation and highly balanced power combinercircuit.The filter has been validated with real LHC beam measurements and is found towork as expected. More work however needs to be done to ensure the effect that thefilter itself has on the beam measurements as the filter could introduce some ringingeffects on the signal. The highly balanced high isolation power combiner has beentested through lab measurements and also shows promising results but long-termtests need to be conducted to ensure the reliability of the component as it will needto endure very high signal levels over long periods of time.
Det system som mäter partikelstrålens position och ansvarar för att extraktion avdenna kan ske under säkra och pålitliga former i Large Hadron Collider (LHC) heterLHC interlock beam position monitor (BPM) och är en viktig del av LHC:s maskinskydd.Det nuvarande system som utför dessa mätningar har vissa begransningaroch till följd av detta har en uppgradering av systemet påbörjats. Detta examensarbetebeskriver utvecklingen av den elektronik som kommer att användas i systemetsanaloga signalkedja som består i huvudsak av ett filter samt en balanserad effektdelareför radiofrekvenser.Filtret har utvärderats genom verkliga mätningar av partikelstrålen och har konstateratsfungera som väntat. Mer arbete krävs dock för att bestämma påverkansom filtret självt har på positionsmätningarna då det introducerar en viss ringandeeffekt på signalerna. Den balanserade effektdelaren har testats i lab och visar ocksåpå lovande resultat men kräver tester över längre tid då denna komponent kommeratt behöva utstå höga signalnivåer under långa tidsperioder.

[EN] The Compact Linear Collider (CLIC) is an electron-positron collider conceived for the study of High-Energy Physics in the TeV center of mass energy region, is based on a two-beam operation principle: instead of using active elements (klystrons), the necessary RF power to accelerate the Main Beam (MB) is obtained from the deceleration of a high-current, moderate energy Drive Beam (DB) in the so-called Power Extraction and Transfer Structures (PETS). These structures emit an RF signal of about 130 MW power at 12 GHz. As this frequency is above the cut-o ff frequency of the fundamental mode for the specified beam pipe dimensions (7.6 GHz), the inference propagates from the PETS to the neighboring devices, including the Beam Position Monitors (BPM). According to the CLIC Conceptual Design Report (CDR), an ef ficient beam position monitoring system for the CLIC DB decelerator needs to meet the following requirements: - It should be as simple and economic as possible, as 41580 units are required, amounting to 75% of all CLIC BPMs. - The signal processing scheme should not be a ffected by the PETS interference. This rules out processing the signals at the beam bunching frequency (12 GHz). - The resulting position signal should detect changes in the beam position whose duration is 10 ns or longer. - The required spatial resolution is 2 um for a 23 mm diameter vacuum pipe. - Wide dynamic range: the electronic acquisition system must be able to process signals with extreme levels, induced by either very high (100 A) or very low (3 A) current beams. This PhD thesis describes the electromagnetic and mechanical design of the first prototype BPM developed for the CLIC Drive Beam and its characterization tests in laboratory and with beam. The first two chapters introduce the CLIC project and review the state-of-the-art beam position monitoring techniques. Chapter 3 presents the design of the BPM. The stripline technology has been selected, as it is the only one among the most commonly used BPM techniques to present a suitable frequency response to filter out the RF interference caused by the PETS. Choosing an appropriate length for the electrodes, it is possible to tune one the periodic notches in the stripline frequency response to 12 GHz. The influence of di erent electromagnetic and geometrical aspects is also studied, such as beam coupling impedance or the ratio between longitudinal and transverse dimensions. The design of the electronic acquisition system is presented in Chapter 4, considering the project requirements in terms of resolution (2 u m), accuracy (20 um) and time resolution (10 ns). Due to the high amount of units required, the number of electronics components has been minimized. As the designed signal processing scheme is based on charge integration, it can be adapted to di erent stripline pick-ups by simply modifying the attenuator settings according to the required output signal levels. The laboratory characterization tests of the prototype stripline BPM, in the low and the high frequency ranges, performed with a thin wire and a coaxial waveguide, respectively, are described in Chapter 5. The measurement results are compared with the theoretical estimation and the electromagnetic field simulations. In addition, the high-frequency test reveals that the first prototype stripline BPM does not provide su cient suppression of the 12 GHz PETS RF interference. An additional study proposed several modifications and guidelines for a second prototype stripline BPM. Finally, Chapter 6 presents the beam tests of the prototype stripline BPM at the CLIC Test Facility 3 (CTF3) in the Test Beam Line (TBL), a scaled version of the CLIC Drive Beam decelerator. Two types of tests were performed: linearity/sensivity and resolution. These results are compared to the ones in the laboratory characterization tests. An upper bound of the resolution is estimated performing a Singular Value Decomposition (SVD) analysis.
[ES] El Colisionador Lineal Compacto (Compact Linear Collider, CLIC), un colisionador de electrones y positrones concebido en el CERN para el estudio de la Física de Altas Energías en la región de los TeV, se basa en un principio de funcionamiento de doble haz: en lugar de emplear elementos activos (klystrons) para proporcionar la potencia RF requerida para acelerar el haz principal (Main Beam, MB), ésta se obtiene de la deceleración de un haz secundario (Drive Beam, DB), de alta corriente y energía moderada, en las llamadas estructuras de extracción y transferencia de potencia (Power Extraction and Transfer Structures, PETS). Estas estructuras emiten una señal interferente RF de más de 130 MW de potencia a 12 GHz, que, por estar localizada en una frecuencia superior a la de corte del modo fundamental en el tubo de vacío del haz (7.6 GHz), se propaga por éste hacia los dispositivos adyacentes, entre los cuales se encuentran los sistemas de monitorización de la posición (Beam Position Monitor, BPM). De acuerdo con el informe conceptual de diseño de CLIC (Conceptual Design Report, CDR) , un sistema eficiente de monitorización de la posición del haz en el decelerador del haz secundario deberá cumplir los siguientes requisitos: - Debe ser lo más sencillo y económico posible, ya que se precisan 41580 unidades: el 75% de todos los BPMs de CLIC. - El procesado de señal en el sistema de adquisición deberá ser inmune a la interferencia generada en las PETS. Esto excluye la solución habitual de procesar las señales del BPM a la frecuencia de pulsado del haz (12 GHz). - La señal de posición resultante del procesado debe ser capaz de detectar cambios en la posición del haz de duración igual o mayor a 10 ns (resolución temporal). - La resolución espacial requerida es de 2 um para un tubo de vacío de 23 mm de diámetro, con una calibración precisa. - Amplio rango dinámico: el sistema electrónico de adquisición del BPM debe poder resistir los altos valores de señal provocados por los casos de desviación extrema del haz nominal (se contempla una desviación máxima de la mitad del radio del tubo), así como detectar las señales inducidas por las configuraciones de haz con menor carga de todas las previstas, cuyos niveles serán muy débiles.
[CAT] El Col·lisionador Lineal Compacte (Compact Linear Collider, CLIC), un col·lisionador d'electrons i positrons concebut per l'estudi de la Física d'Altes Energies a la regió dels TeV (energía del centre de massa), es basa en un principi de funcionament de doble feix:en lloc de fer servir elements actius (klystrons) per proporcionar la potència RF requerida per accelerar el feix principal (Main Beam, MB), aquesta s'obtè de la desacceleració d'un feix secundari (Drive Beam, DB), d'alt corrent i energia moderada, a les anomenades estructures d'extracció i transferència de potència (Power Extraction and Transfer Structures, PETS). Aquestes estructures emeten una senyal interferent RF de més de 130 MW de potència a 12 GHz, que, pel fet d'estar localitzada a una freqüència superior a la de tall del mode fonamental al tub de buit del feix (7.6 GHz), es propaga a través d'aquest fins els dispositius adjacents, entre els quals trobem els sistemes de monitorització de la posició (Beam Position Monitor, BPM). D'acord amb l'informe conceptual de disseny de CLIC (Conceptual Design Report, CDR), un sistema eficient de monitorització de la posició del feix al desaccelerador del feix secundari haurà de complir els següents requisits: ¿ - Ha de ser el més senzill i econòmic possible, ja que es necessiten 41580 unitats: el 75% de tots els BPMs de CLIC. ¿ - El processat de la senyal al sistema d'adquisició haurà de ser inmune a la interferència generada als PETS. Això exclou la solució habitual de processar les senyals del BPM a la freqüència de pulsacions del feix (12 GHz). ¿- La senyal de posició resultant del processat ha de ser capaç de detectar canvis a la posició del feix de durada igual o més gran que 10 ns (resolució temporal). ¿- La resolució espaial necessària és de 2 um per a un tub de buit de 23 mm de diàmetre. ¿- Ampli rang dinàmic: el sistema electrònic d'adquisició del BPM ha de poder processar senyals amb nivells extrems, induïdes per feixos de molt alt (100 A) i molt baix (3 A) corrent.
Benot Morell, A. (2016). Beam position monitoring in the clic drive beam decelerator using stripline technology [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64067
TESIS

The work for this thesis is in line with the field of Instrumentation for Particle Accelerators, so called Beam Diagnostics. It is presented the development of a series of electro-mechanical devices called Inductive Pick-Ups (IPU) for Beam Position Monitoring (BPM). A full set of 17 BPM units (16 + 1 spare), named BPS units, were built and installed into the Test Beam Line (TBL), an electron beam decelerator, of the 3rd CLIC Test Facility (CTF3) at CERN ¿European Organization for the Nuclear Research¿. The CTF3, built at CERN by an international collaboration, was meant to demonstrate the technical feasibility of the key concepts for CLIC ¿Compact Linear Collider¿ as a future linear collider based on the novel two-beam acceleration scheme, and in order to achieve the next energy frontier for a lepton collider in theMulti-TeV scale. Modern particle accelerators and in particular future colliders like CLIC requires an extreme alignment and stabilization of the beam in order to enhance its quality, which rely heavily on a beam based alignment techniques. Here the BPMs, like the BPS-IPU, play an important role providing the beam position with precision and high resolution, besides a beam current measurement in the case of the BPS, along the beam lines. The BPS project carried out at IFIC was mainly developed in two phases: prototyping and series production and test for the TBL. In the first project phase two fully functional BPS prototypes were constructed, focusing in this thesis work on the electronic design of the BPS on-board PCBs (Printed Circuit Boards) which are based on transformers for the current sensing and beam position measurement. Furthermore, it is described the monitor mechanical design with emphasis on all the parts directly involved in its electromagnetic functioning, as a result of the coupling of the EM fields generated by the beam with those parts. For that, it was studied its operational parameters, according the TBL specifications, and it was also simulated a new circuital model reproducing the BPS monitor frequency response for its operational bandwidth (1kHz-100MHz). These prototypes were initially tested in the laboratories of the BI-PI section¿Beam Instrumentation - Position and Intensity¿ at CERN. In the second project phase the BPS monitor series, which were built based on the experience acquired during the prototyping phase, the work was focused on the realization of the characterization tests to measure the main operational parameters of each series monitor, for which it was designed and constructed two test benches with different purposes and frequency regions. The first one is designed to work in the low frequency region, between 1kHz-100MHz, in the time scale of the electron beam pulse with a repetition period of 1s and an approximate duration of 140ns. This kind of test setups called Wire Test-bench are commonly used in the accelerators instrumentation field in order to determine the characteristic parameters of a BPM (or pick-up) like its linearity and precision in the position measurement, and also its frequency response (bandwidth). This is done by emulating a low current intensity beam with a stretched wire carrying a current signals which can be precisely positioned with respect the device under test. This test bench was specifically made for the BPS monitor and conceived to perform the measurement data acquisition in an automated way, managing the measurement equipment and the wire positioning motors controller from a PC workstation. Each one of the BPS monitors series were characterized by using this system at the IFIC labs, and the test results and analysis are presented in this work. On the other hand, the high frequency tests, above the X band in the microwave spectrum and at the time scale of the micro-bunch pulses with a bunching period of 83ps (12GHz) inside a long 140ns pulse, were performed in order to measure the longitudinal impedance of the BPS monitor. This must be low enough in order to minimize the perturbations on the beam produced at crossing the monitor, which affects to its stability during the propagation along the line. For that, it was built the high frequency test bench as a coaxial waveguide structure of 24mm diameter matched at 50¿ and with a bandwidth from 18MHz to 30GHz, which was previously simulated, and having room in the middle to place the BPS as the device under test. This high frequency test bench is able to reproduce the TEM (Transversal Electro-Magnetic) propagative modes corresponding to an ultra-relativistic electron beam of 12GHz bunching frequency, so that the Scattering parameters can be measured to obtain the longitudinal impedance of the BPS in the frequency range of interest. Finally, it is also presented the results of the beam test made in the TBL line, with beam currents from 3.5A to 13A (max. available at the moment of the test). In order to determine the minimum resolution attainable by a BPS monitor in the measurement of the beam position, being the device figure of merit, with a resolution goal of 5¿m at maximum beam current of 28A according to the TBL specifications.
García Garrigós, JJ. (2013). Development of the Beam Position Monitors for the Diagnostics of the Test Beam Line in the CTF3 at CERN [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34327
TESIS

Orientador: Hugo Enrique Hernadez Figueroa
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Atualmente está em fase de projeto o novo acelerador de elétrons do Laboratório Nacional de Luz Síncrotron (LNLS). Este acelerador de partículas, denominado Sirius, é constituído por diversos sistemas de instrumentação, sendo um deles de particular interesse para o diagnóstico de posição do feixe de elétrons estocado no acelerador. Este sistema, denominado monitor de posição de feixe, é constituído por sua vez por outros subsistemas, dentre os quais uma eletrônica de RF, dedicado a fazer processamento analógico de sinais de Rádio Frequência advindos de sensores que interagem eletromagneticamente com o feixe de elétrons. Esta eletrônica de RF deve condicionar o sinal, fornecendo ganho, filtragem, linearidade e estabilidade necessárias na faixa de operação de potências de entrada para que o sinal possa ser digitalizado. Este trabalho tem por objetivo descrever a respeito do desenvolvimento desta eletrônica, abarcando o projeto do circuito de RF de alta linearidade e alta estabilidade, implementação em placa de circuito impresso e testes em bancada e no acelerador de elétrons UVX, do LNLS
Abstract: The new electron accelerator of the Brazilian Synchrotron Light Laboratory (LNLS) is being designed to provide users with more brilliant photon beams. This particle accelerator, called Sirius, is composed of hundreds of instrumentation systems that are responsible for the machine operation. The Beam Position Monitor System is dedicated to monitor the position of the electron beam stored inside the vacuum chamber of the machine. It is composed by a subsystem called RF Front-End, dedicated to the analog processing of the beam signals that is originated by the interaction between the ultra-relativistic electromagnetic field of the electron beam and sensors specially designed for it. The RF Front-End electronics have been designed to provide filtering and gain with high linearity and stability along all the input power range. This work presents the design of the electronics, its implementation in printed-circuit board and tests results that have been performed in the laboratory and with a real beam signal
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica

The stability of the photon beam position on synchrotron beamlines is critical for most if not all synchrotron radiation experiments. On wiggler and bend magnet beamlines, the vertical position is most critical due to the large horizontal width of the beam. The position of the beam at the experiment or optical element location is set by the position and trajectory of the electron beam source as it traverses the magnetic field of the bend magnet or the insertion device. Thus an ideal photon beam monitor would be able to simultaneously measure the photon beam’s vertical position and angle, or its position in phase space. X-ray diffraction is commonly used to prepare a monochromatic beam on x-ray beamlines usually in the form of a double crystal monochromator using perfect crystals. Diffraction from crystals couples the photon wavelength or energy to the incident angle on the crystal or lattice planes within the crystal. A monochromatic beam from such a monochromator will contain a spread of energies due to the vertical divergence of the photon beam from the source. This range of energies can easily cover the absorption edge of an element such as iodine at 33.17keV. It has been found that a system composed of a double crystal monochromator and an iodine filter that horizontally covers part of the monochromatic beam and an imaging detector can be used to independently and simultaneously measure the position and angle of the photon beam. This information can then be translated back to determine the vertical position and angle, or vertical phase space, of the electron beam source. This approach to measurement of the phase space of the source has not been done before and thus this study is the first of its kind. The goal of this thesis is to investigate the use of this combined monochromator, filter and detector as a phase space beam position monitor. The system was tested for sensitivity to position and angle under a number of synchrotron operating conditions (normal operations and special operating modes where the beam is intentionally altered in position and angle). These results were compared to other methods of beam position measurement from the literature to assess the utility of such a system as a beam diagnostic, a feedback element for electron beam control and a source of information that could be used to correct the experimental data to account for beam position and angle motion.

碩士
國立清華大學
先進光源科技學位學程
104
In a short-wavelength single-pass high-gain free electron laser system, precision control of beam position is of critical importance. Resolution of the beam position monitor (BPM) to sub-micrometer level is often required. Cavity-type BPM was invented in the 60’s. They have been widely used in accelerator systems that require precise detection of beam positions since then. Thanks to the continuous efforts by major accelerator laboratories to improve cavity BPM performance, it has now become an important beam diagnostic tool. In contrast to the cavities for particle acceleration, cavity BPM usually operates at TM110 mode in which the longitudinal electric field on the cavity axis is null and it varies linearly along one transverse direction. Hence, the beam at different positions can be detected according to the amplitude of the longitudinal electric field excited by the beam. In this study, we try to design a 2.5 GHz, sub-micrometer resolution cavity BPM for the proposed NSRRC THz/VUV FEL facility. This design is based on the BPMs that are used in the Spring-8 SACLA X-ray FEL as well as the KAERI THz FEL facilities. We start our study with the physics of the cavity BPM and the microwave characteristics of the structure to estimate the coarse dimensions of the BPM cavity. We then use the HFSS Eigen-mode Solver to calculate the microwave properties of the cavity and optimize the BPM dimensions for sub-micrometer resolution detection. On the other hand, we simulate the electron beam passing through the BPM and obtain the time domain signal picked up from the cavity by using the computer code -- CST Particle Studio. The deduced BPM resolution according to the simulated cavity picked up signals by CST is 2.2μm. Further, a prototype 2.5 GHz cavity BPM has been fabricated for bench measurement of microwave characteristics, the results agree well with the computer simulation results.