Academic literature on the topic 'Inductively coupled radio frequency plasma'

The electrodeless plasma discharge is typically driven by radio frequency (RF) power supply within the range (0.2 ¡
40 MHz). The applied power is coupled into the plasma inductively called inductively coupled plasma (ICP). RF ICP technique has achieved significance importance in a diversity of research and industrial applications for over the last threes decades. It is still required to undertake both theoretical and experimental research. In this work, RF ICP technique is applied on the torch modeling in 2D. Based on extended electromagnetic vector potential representation, an axisymmetric model in 2D is proposed for the calculations of the electromagnetic fields in an RF ICP torch. The influence of axial vector potential is included to the vector potential formulations. This is achieved by imposing a helical current carrying wire configuration. The corresponding governing equations are solved numerically by applying finite element method (FEM) using commercial partial differential equation solver (Flex PDE3). Based on this model, the plasma behavior and properties are examined in terms of plasma parameters. Besides, a comparative iii analysis is made between proposed model called helical configuration and the one currently available in the literature called circular configuration. This study shows relatively little difference between temperature fields predicted by two models. However, significant difference is observed between corresponding flows and electromagnetic fields. Especially, tangential flow which is observed in helical configuration vanishes in circular configuration. The proposed model offers an effective means of accounting for the variations of the helical coil geometry on the flow and temperature fields and achieving a better representation of the electromagnetic fields in the discharge. Finally, it is concluded that minimum number of turns (n = 2) yields significant difference between two models whereas, maximum allowable number of turns yield no distinctions on the results of two models in terms of azimuthally applied current. However, axial effect of current still exists but very small with respect to the result obtained with minimum number of turns.

Direct solid sampling is an area of analytical research that has generated a large amount of interest in recent years. Two analysis systems offering fast and nondestructive methods of determining the elemental composition of substances, without requiring complicated sample preparation procedures, are laser ablation inductively coupled plasma mass spectroscopy (LA-ICPMS) and radio frequency glow discharge mass spectroscopy (rf-GDMS). A Cetac LSX-200 laser system coupled to a LECO Renaissance ICPMS was utilized to analyze coal and ash samples prepared by incorporation into a lithium borate matrix to form a disk. In addition, a VG 9000 Glow Discharge Mass Spectrometer (GDMS) with Nier-Johnson reverse ion optic geometry, equipped with a radio frequency source (rf-source), was used for the determination of nonconductors or insulators in addition to the normal metals and semiconductors previously determined by dc-source analysis. Further addition of a pulse generator to the rf-source resulted in a variable duty cycle, allowing greater ionization efficiency without the risk of catastrophic damage to the sample. The results of this research indicate that the LA-ICPMS system can be used to directly determine the composition of ash samples, with further method development, and that the Prf-GDMS system can be used successfully to analyze nonconductive solid samples including bone tissue.

Tato diplomová práce se zabývá problematikou plazmového nanášení bioaktivních keramických povlaků hydroxylapatitu s využitím technologie radio-frekvenčně buzeného indukčně vázaného plazmatu. Cílem bylo optimalizovat proces a nanést kompaktní hydroxylapatitové povlaky na substráty z titanové slitiny Ti6Al4V. Nanesené vzorky byly následně podrobeny analýzám povrchové drsnosti, mikrostruktury a fázového složení. Ze získaných výsledků byly vyvozeny závěry, které byly srovnány s dalšími odbornými pracemi zabývajícími se příbuznou problematikou.

Thesis (M.S.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains v, 36 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 21).

The International Thermonuclear Experimental reactor (ITER), the world’s largest experimental facility in the realm of nuclear fusion for energy production, requires two Neutral Beam Injectors (NBI) rated for the total power of 33 MW for plasma heating and current drive. The ITER NBI includes an ion source which can produce 40 A of D¯ ions beams for 3600 s, accelerated at the energy of 1 MeV. The requirements for the ITER NBI are quite demanding and have never been achieved before all together in a single device. This specifically called for a development of the ITER Neutral Beam Test Facility (NBTF) called PRIMA (Padova Research on ITER Megavolt Accelerator) to carry out an international R&D program for the achievement of the ITER NBI requirements and the optimization of the operation in advance of the future use in ITER. The facility will host two experiments, SPIDER (Source for the Production of Ions of Deuterium Extracted from RF plasma), the full-size prototype of ITER RF ion source, and MITICA (Megavolt ITER Injector and Concept Advancement), the full-scale prototype of the ITER heating NBI. The NBTF in Padova, Italy, is ready, MITICA is currently under construction and SPIDER has been in operation since beginning of June 2018. The NBI ion source was initially based on filament type arc source, while for ITER the inductively coupled (IC) radio frequency (RF) ion source have been finally chosen in 2007. This is because RF sources present several advantages with respect to arc solutions; they have fewer parts and require less maintenance. In these ion sources, radio frequency plasma is generated at the frequency of 1 MHz and is characterized by high RF power density and low operational pressure (around 0.3 Pa). In the last decades, IC ion sources have been developed, studied and experimented at the Max-Planck-Institut für Plasmaphysik (IPP) in Garching, Germany. The most recent one is ELISE (Extraction from a Large Ion Source Experiment), which is able to operate with both Hydrogen and Deuterium gas species and has half the size of ITER NBI source. Other accompanying activities have been recently launched at Consorzio RFX, Padova, Italy within the ITER NBI work program; one of them is a relatively small ion source called NIO1 (Negative Ion Optimization 1) working at 2 MHz, developed in order to gain experience on ion source operation and to study specific physics and engineering topics on a more flexible and accessible device than the SPIDER and MITICA. In addition, a small experimental test facility called HVRFTF (High Voltage Radio Frequency Test Facility) based on a high voltage resonance circuit that feeds a couple of electrodes in vacuum has been started at Consorzio RFX in 2014 to address and study the voltage holding capability of the RF components in the ion source at 1 MHz. The research endeavor during the three years of my PhD was carried out in the frame of the RF R&D task of the NBTF work-program at Consorzio RFX and during the mobility periods at the IPP. I have had the opportunity to work on two main lines: the first was dedicated towards the study of the RF power transfer efficiency of IC RF ion sources and the development of suitable models that will permit to explore possible improvements (in the future). In fact, the higher the efficiency, the lower can be the feeding power to the ion source and this may lead to a lower requirement both for cooling and for electrical insulation of the RF circuit components installed on the source. I have studied and analyzed several plasma heating mechanisms (like ohmic and stochastic heating in particular) and I have developed an electrical model which is responsible for describing the power transfer to the plasma. The first approach was based on a transformer model, and then a multi current filament model has been developed. This model is capable to account for the currents in the passive metallic structure within the driver region of the ion source and with this; it is able to overcome the main limitation of the transformer model. Furthermore, I have integrated all the models to develop a novel methodology to evaluate the efficiency of the RF power transfer to the hydrogen plasma in a cylindrical source. Then, I have implemented the methodology in a MATLAB® code and applied it to the driver of ELISE and NIO1 ion sources showing the results in terms of plasma equivalent resistance and power transfer efficiency obtained as a function of applied frequency and plasma parameters (electron density and gas pressure). The second part of my work was directed towards the design, construction and set-up of the HVRFTF. I gave an important contribution in terms of the electrical characterization of the RF resonance circuit components (mainly the two solenoid coupled inductor), thermal analysis of the electrodes placed inside the vacuum vessel, analyses and design of an efficient shielding from the electro-magnetic radiations foreseen during the operation of the test facility. All this contributed towards the success in the set-up of the test facility which is now in operation. The thesis is structured as follows: Chapter 1 and 2 are introductory chapters on the present energy scenario in the world, the role of the thermo-nuclear fusion and the main fusion experimental device called ITER. The requirement of additional heating systems in ITER along with the description of Neutral beam injection (NBI) system and relevant ion sources (SPIDER, ELISE and NIO1) are presented in these chapters. Then, the thesis is divided into two main parts: Part 1 – From Chapter 3 to Chapter 6 - describes my work on the power transfer efficiency to the plasma of the inductively coupled radio frequency ion sources. Part 2 – From Chapter 7 to chapter 10 - summarizes first the aim of the HVRFTF then reports my contribution to its design and set-up. Lastly, the overall conclusion highlighting the most significant results obtained from the research described in both the parts of the thesis is discussed and a further possible research activity is highlighted for the future work. Throughout the journey of the PhD, I have had the opportunity to grow and acquire different research competences ranging from conceptual studies, modeling activities, practice on several numerical codes and also experimental work, in an international context.
Il reattore sperimentale ITER, il più grande esperimento nel settore della produzione di energia da fusione nucleare, richiede di essere equipaggiato con due sistemi d’iniezione di fasci di particelle neutre (chiamato ITER NBI nel seguito), caratterizzati da una potenza complessiva di 33 MW, per contribuire al riscaldamento del plasma e controllo della relativa corrente. ITER NBI comprende una sorgente di ioni negativi che può produrre un fascio di ioni di deuterio accelerati all’energia di 1 MeV, per una durata di 3600 s. L’insieme dei requisiti richiesti ad ITER NBI non sono mai stati raggiunti contemporaneamente nello stesso esperimento. Ciò ha motivato lo sviluppo di un’infrastruttura sperimentale: “the ITER Neutral Beam Test Facility (NBTF)”, chiamata anche PRIMA (Padova Research on ITER Megavolt Accelerator), che ha lo scopo di portare avanti un progetto di ricerca internazionale finalizzato alla dimostrazione della possibilità di raggiungere i requisiti specificati per ITER NBI e alla crescita di conoscenza e competenza nella sperimentazione, prima dell’uso futuro in ITER NBTF ospiterà due esperimenti: SPIDER (Source for the Production of Ions of Deuterium Extracted from an RF plasma), il prototipo a piena scala della sorgente a ioni negativi di ITER NBI, e MITICA (Megavolt ITER Injector and Concept Advancement), il prototipo a piena scala dell’intero ITER NBI. NBTF è stata completata ed ha sede a Padova, in Italia; MITICA è attualmente in costruzione e SPIDER è in operazione dall’inizio di giugno 2018. La sorgente di ioni scelta inizialmente per ITER NBI era del tipo ad arco, ma dal 2007 il progetto dell’NBI è stato sviluppato considerando sorgenti di ioni prodotti in un plasma generato secondo il principio dell’accoppiamento induttivo a radiofrequenza (RF). Queste sorgenti presentano diversi vantaggi rispetto alle sorgenti ad arco: hanno un numero minore di componenti e richiedono minor manutenzione. Le sorgenti RF di ITER NBI operano alla frequenza di 1 MHz, sono caratterizzate da una densità di potenza piuttosto elevata e basso valore di pressione del gas all’interno della camera (0,3 Pa circa). Queste tipologie di sorgenti ioniche sono state studiate e sviluppate negli ultimi decenni presso il Max-Planck-Institut für Plasmaphysik (IPP), dove sono stati realizzati e testati diversi dispositivi sperimentali. Il più recente di essi, chiamato ELISE (Extraction from a Large Ion Source Experiment), è caratterizzato da dimensioni pari a metà di quelle previste per la sorgente ionica di ITER NBI. Altre attività sperimentali di supporto alla ricerca e sviluppo in questo settore sono state avviate presso il Consorzio RFX; una di queste consiste nella realizzazione di una sorgente a ioni negativi relativamente piccola, chiamata NIO1 (Negative Ion Optimization 1), che lavora alla frequenza di 2 MHz, sviluppata per fare esperienza sul funzionamento di sorgenti di ioni negativi e studiare problematiche specifiche di interesse per ITER NBI in un apparato sperimentale molto più flessibile ed accessibile rispetto a SPIDER e MITICA. Inoltre, la realizzazione di un ulteriore dispositivo sperimentale, chiamato HVRFTF (High Voltage Radio Frequency Test Facility), basato su un circuito risonante in alta tensione che polarizza una coppia di elettrodi in vuoto, è stata avviata presso il Consorzio RFX nel 2014 per studiare specifiche problematiche relative alla tenuta della tensione in vuoto di componenti del circuito a radiofrequenza della sorgente di ioni a 1MHz. Il lavoro di ricerca durante i tre anni del mio PhD è stato portato avanti nell’ambito del programma di ricerca e sviluppo sulle sorgenti ioniche a radiofrequenza presso il Consorzio RFX, e durante i periodi di “mobility” presso il laboratorio IPP. Ho avuto l’opportunità di approfondire due tematiche principali: la prima era indirizzata allo studio dell’efficienza del trasferimento di potenza al plasma delle sorgenti di ioni tipo IC RF e allo sviluppo di modelli allo scopo di esplorare in futuro possibili miglioramenti. Infatti, maggiore è l’efficienza, minore è la potenza richiesta al generatore e ciò comporta requisiti meno severi per il sistema di raffreddamento e sollecitazioni inferiori in termini di tensione elettrica applicata. Ho studiato i diversi meccanismi di riscaldamento del plasma (come il riscaldamento ohmico ed in particolare il riscaldamento stocastico) ed ho studiato come descrivere il trasferimento di potenza ad un plasma di idrogeno. Il primo modello sviluppato si basa sullo schema del trasformatore; successivamente ho contribuito significativamente a sviluppare un modello “a multi filamenti” di corrente. Questo modello riproduce le correnti indotte nelle strutture passive presenti nella regione del driver della sorgente di ioni ed è in grado di superare le limitazioni del modello del trasformatore. Ho integrato tutti i modelli per sviluppare una nuova metodologia per la stima dell’efficienza del trasferimento di potenza nei plasmi di idrogeno generati in sorgenti cilindriche. Ho poi implementato la metodologia in MATLAB®, applicandola ai casi delle sorgenti ioniche di ELISE e NIO1, presentando i risultati ottenuti in termini di stima della resistenza equivalente di plasma e di efficienza del trasferimento di potenza come funzione della frequenza applicata e dei parametri di plasma (densità elettronica e pressione del gas). La seconda parte del mio lavoro si è svolta nell’ambito dello sviluppo della HVRFTF. Ho dato importanti contributi che sono consistiti nella caratterizzazione dei componenti del circuito risonante a radiofrequenza (in particolare dell’induttore composto da due solenoidi accoppiati magneticamente), nelle analisi termiche degli elettrodi posti nella camera da vuoto, nelle analisi e progetto di un sistema di schermatura efficace delle radiazioni elettromagnetiche generate dall’operazione dell’esperimento. Tutto ciò ha contribuito al positivo completamento dell’apparato sperimentale, attualmente in funzione. La tesi è strutturata come segue: I capitoli 1 e 2 sono di tipo introduttivo sull’attuale scenario energetico, sul ruolo della fusione termonucleare controllata e del principale esperimento internazionale ITER. In questi capitoli inoltre sono presentati i requisiti del sistema di riscaldamento del plasma di ITER, la descrizione del sistema di iniezione di neutri (NBI) e delle sorgenti ioniche di interesse (SPIDER, ELISE e NIO1). Poi, la tesi è suddivisa in due parti: Parte 1- dal capitolo 3 al capitolo 6- che tratta del lavoro che ho svolto sul problema dell’efficienza del trasferimento induttivo di potenza al plasma nelle sorgenti ioniche. Parte 2 - dal capitolo 7 al capitolo 10- che riassume lo scopo della “HVRFTF” e descrive il mio contributo al suo progetto e realizzazione. Infine, nelle conclusioni ho discusso i più significativi risultati ottenuti dal lavoro di ricerca presentato nelle Parti 1 e 2 di questa tesi evidenziando i possibili sviluppi futuri. Durante il percorso del dottorato di ricerca, ho avuto l'opportunità di crescere e acquisire diverse competenze di ricerca che vanno dagli studi concettuali, alle attività di modellizzazione, alla pratica su diversi codici numerici e anche al lavoro sperimentale, in un contesto internazionale.

Abstract An experimental study is conducted to determine the property fields of 40 MHz argon radio frequency inductively coupled plasma using optical emission spectroscopy. The pure argon plasma was operated at the input power of 0.3 kW and under atmospheric pressure. 29 atomic argon lines with upper level energies ranging from 12.9 to 15.5 eV, continuum emission and line width are used to evaluate plasma parameters such as temperature and electron number density. Since 40 MHz plasma is in almost complete nonequilibrium, the validaty and accuracy of most usual spectroscopic methods are questioned. Analysis based on the Boltzmann diagram, line-to-continuum intensity ratio, population of continuum extrapolated level, and continuum intensity reveals the departure from thermodynamic equilibrium in the plasma. Among these methods, the Boltzmann diagram method is shown to provide reliable plasma excitation temperature as long as the Boltzmann plot is drawn based on enough spectra lines covering from infrared to ultraviolet regions. The continuum emission at wavelengths within visible region can give good estimation of the electron density by using excitation temperature in the continuum relation. The line-to-continuum is not a reliable method for the temperature measurement of nonequilibrim plasma. The electron density obtained from the Saha plot can provide rough estimation of the electron density. It is shown that the electron-atom interaction contribution to the continuum radiation is more important than being expected before for the argon plasma in our study. The non-axisymmetric distribution of the emission was found to exist within the coil zone of the plasma, which may affect the estimation of the local emission coefficient, and consequently the measured plasma fields.

A two-dimensional numerical model has been developed to investigate the induction electromagnetic (EM) field and the thermo-fluid field in a radio frequency inductively coupled plasma (RF-ICP). Various physical and chemical phenomena have been considered such as the induction heating, plasma generation, and the in-flight particle interaction with the plasma jet. This model has been applied to the induction plasma spray process operated in a vacuum chamber. The partially stabilized zirconia powder (PSZ) has been used as an example for the feedstock. The effects of power input, standoff distance and powder injection position on the plasma and particle behaviors have also been investigated and discussed.