Journal of Microwave Power and Electromagnetic Energy, 2017
ABSTRACT In connection with recently published results, two 2.45 GHz microwave plasma sources wer... more ABSTRACT In connection with recently published results, two 2.45 GHz microwave plasma sources were designed: a coaxial electron cyclotron resonance-type operating between 0.01 and 10 Pa and a collisional-type for higher pressure range, 1–100 Pa. The primary goal was to build self-matched plasma sources, which can maintain low reflected power levels without any impedance matching component. The microwave field was supplied to each plasma source via a coaxial feed from a solid-state microwave generator with adjustable power between 0 and 200 W and adjustable frequency from 2.4 to 2.5 GHz. The adjustable frequency of the generator is intended to be used as backup matching means if the reflected power increases above a set value; an automatic adjustment loop enables the microwave generator to start sweeping the frequency band until the lowest reflected power level is found. The modelling method used to obtain self-adapted plasma sources is explained; the performance of each source is evaluated by measuring the efficiency of the microwave power transmitted inside the plasma vs. gas pressure, gas type and microwave forward power level. Results of plasma source testing in industrial applications such as nanocrystalline diamond deposition on 4 inch silicon wafers and stainless steel nitriding are presented.
Il est très important pour moi de rédiger ces quelques lignes pour remercier les nombreuses perso... more Il est très important pour moi de rédiger ces quelques lignes pour remercier les nombreuses personnes qui ont permis ce travail. En effet, que ce soit mon entourage scientifique, familial ou mon cercle d'amis, tous ont influencés mon travail, directement ou plus subrepticement. Je tiens à remercier en premier lieu Christian Trassy, Directeur de Recherche et Yves Fautrelle, Professeur, directeurs successifs du laboratoire EPM, pour m'avoir accueilli dans leur laboratoire. Je remercie également Eric Beaugon, Maître de Conférence et directeur du CRETA, pour nous avoir hébergé dans son laboratoire la première année de ma thèse. Mes remerciements s'adressent aussi à Johann Collot, Professeur et directeur du LPSC, pour avoir accueilli notre équipe, le Centre de Recherche Plasma-Matériaux-Nanostructures (CRPMN), dans son laboratoire. Je dois beaucoup à la commission Européenne, qui grâce au projet MATECO (contrat STRP 505928), a apporté une grande partie des moyens consacrés à mes travaux de thèse, et je l'en remercie vivement. J'adresse mes remerciements aux membres du jury de ma thèse, tout d'abord à Caroline Boisse-Laporte, Chargée de Recherche, et Yvan Ségui, Directeur de Recherche, pour le dur travail de rapporteur qu'ils ont dû accomplir. Je remercie doublement Yves Pauleau, Professeur, d'avoir accepté d'être président du jury et de m'avoir formé lors de mon DEA. Merci aussi à Michel Touzeau, Directeur de Recherche, pour avoir accepté d'être membre du jury et pour le temps qu'il m'a consacré pour tenter de comprendre mes plasmas d'oxygène. Je remercie également Agnès Granier d'avoir accepté d'être membre de mon jury et pour les corrections judicieuses qu'elle a suggérées pour ma thèse. J'adresse des remerciements très particuliers à Ana Lacoste, Professeur et directeur de ma thèse, pour ses conseils, son soutien tout au long de ma thèse, la confiance qu'elle m'a accordée et ses idées lumineuses qui m'ont permis d'avancer lorsque tout espoir semblait perdu. J'exprime aussi toute ma gratitude envers Jacques Pelletier, Directeur de Recherche, directeur du CRPMN et co-directeur de ma thèse, pour ses conseils avisés, son optimisme qui permet toujours de faire avancer l'équipe, pour les orientations qu'il a pu me donner et pour m'avoir proposé cette thèse. Mes remerciements s'adressent aussi à Michel Moisan, Professeur et directeur du Groupe de Physique des Plasmas de l'Université de Montréal, pour m'avoir accueilli au sein de son équipe durant un mois pour modéliser mon plasma. Bien entendu, je remercie aussi Kremena Makasheva, Docteur, sans qui la modélisation n'aurait pas été possible et pour le temps qu'elle y a consacré, je la remercie également pour sa bonne humeur, son humour et pour m'avoir sorti au Canada sans quoi je me serais sévèrement ennuyé.
Final report on bunched efficiency of proposed high frequency ECR source for production of radioa... more Final report on bunched efficiency of proposed high frequency ECR source for production of radioactive isotopes needed for beta beam
Microwaves are frequently used to produce high density plasmas for industrial and laboratory appl... more Microwaves are frequently used to produce high density plasmas for industrial and laboratory applications, because they present several advantages when compared to radio-frequency discharges and discharges created using electrodes. Stable and reliable microwave plasma equipment based on magnetrons, and designed for automatic control of the operating parameters has already proved its efficiency in low temperature diamond deposition, exhaust gas abatement, thin-film deposition, etc. However, larger-scale processing with high density and uniform plasma is mandatory for surface treatments to get uniform etching or deposition rates. To meet these industrial requirements AuraWave, an ECR microwave plasma source operating in the 10-2–1 Pa pressure range, and Hi-Wave, a collisional plasma source for higher pressure gas processing (i.e. 1 – 100 Pa) have been designed. Furthermore, because each plasma source is powered by its own microwave solid-state generator, multiple sources operating in ...
2017 IEEE International Conference on Plasma Science (ICOPS), 2017
Large scale industrial processes for surface treatment require uniform, dense, and quiescent plas... more Large scale industrial processes for surface treatment require uniform, dense, and quiescent plasma. One of the strategies in achieving this latter consists in distributing several microwave applicators forming a 2D or 3D network configuration 1, which permits plasma density exceeding the critical density $n_{c}$defined by $n_{c}=\omega _{0}^{2}m_{e}\varepsilon _{0}/e^{2}$with $\omega _{0}$the microwave angular frequency, $\varepsilon _{0}$the vacuum permittivity and $m_{e}$the mass of the electron. Furthermore, integrating microwave applicators designed without any need of complicated matching system proved to be interesting in order to achieve fine tuning of the plasma spatial distribution, hence uniform and dense plasma over large area 2.
LPSC has developed a 60 GHz Electron Cyclotron Resonance (ECR) Ion Source prototype called SEISM.... more LPSC has developed a 60 GHz Electron Cyclotron Resonance (ECR) Ion Source prototype called SEISM. The magnetic structure uses resistive polyhelix coils designed in collaboration with the French National High Magnetic Fields Facility (LNCMI) to produce a CUSP magnetic configuration. A dedicated test bench and appropriate electrical and water cooling environments were built to study the validity of the mechanics, the thermal behaviour and magnetic field characteristics obtained at various current intensities. During the last months, measurements were performed for several magnetic configurations, with up to 7000 A applied on the injection and extraction coils sets. The magnetic field achieved at 13000 A is expected to allow 28 GHz ECR condition, so by extrapolation 60 GHz should be possible at about 28000 A. However, cavitation issues that appeared around 7000 A are to be solved before carrying on with the tests. This contribution will recall some of the crucial steps in the prototype...
High-density reactive species plasmas uniformly covering large surface areas are required for sem... more High-density reactive species plasmas uniformly covering large surface areas are required for semi-conductor processing. Novel, self-matched plasma sources using microwave solid state generators have been developed for this purpose. The technology applied, based on automatic frequency tuning, allowed to eliminate the impedance matching system. Large surface plasmas have been achieved by using a distribution of elementary sources. A big campaign of plasma density measurement using a Langmuir probe has allowed to create a database for different plasma conditions for a single source. Thanks to an internally developed software, the density obtained with several sources in various distribution configurations has been simulated. The position and the power of each source have been optimized and the calculations have been validated by experimental measurements. High plasma densities >1011 cm−3 over large areas >400 mm in diameter with only 13 plasma sources have been achieved with all...
A careful study of pulsed mode operation of the PHOENIX ECR ion source has clearly demonstrated t... more A careful study of pulsed mode operation of the PHOENIX ECR ion source has clearly demonstrated the reality of an unexpected transient current peak, occurring at the very beginning of the plasma breakdown. This regime was named the Preglow, as an explicit reference to the Afterglow occurring at the microwave pulse end. After the transient Preglow peak, the plasma regime relaxes to the classical steady state one. Argon Preglow experiments performed at LPSC are presented. A theoretical model of ECR gas breakdown in a magnetic trap, developed at IAP, showing satisfactory agreement with the experimental results is suggested. Corresponding Author : [email protected]
Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta... more Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta Beam has outstanding capabilities to contribute to precision measurements of the parameters governing neutrino oscillations. The FP7 collaboration EUROnu (2008-2012) is a design study that will review three facilities (Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance, will give means to the European research authorities to make decisions on future European neutrino oscillation facilities. "Beta Beams" produce collimated pure electron (anti)neutrinos by accelerating beta active ions to high energies and having them decay in a storage ring. Using existing machines and infrastructure is an advantage for the cost evaluation; however, this choice is also constraining the Beta Beams. Recent work to make the Beta Beam facility a solid option will be described: production of Beta Beam isotopes, the 60 GHz pulsed E...
choice is also constraining the Beta Beams. The isotope pair of choice for the Beta Beam is 6 He ... more choice is also constraining the Beta Beams. The isotope pair of choice for the Beta Beam is 6 He and 18 Ne. However before the EUROnu studies one of the needed isotopes, 18 Ne, could not be produced in rates that satisfy the needs for physics reach of the Beta Beam. Therefore, studies of alternative beta emitters, 8 Li and 8 B, with properties interesting for a Beta Beam have been proposed and have been studied within EUROnu. These alternative isotopes could be produced by using a small storage ring, in which the beam traverses a target, creating the 8 Li and 8 B isotopes. This Production Ring, the injection Linac and the target system have been evaluated. Measurements of the cross-section of the reactions to produce the Beta Beam isotopes show interesting results. A device to collect the produced isotopes from the target has been developed and tested. However, the obtained rates of the 8 Li and 8 B, using the Production Ring for production of 8 Li and 8 B, is not yet, according to simulations, giving the rates of isotopes that would be needed. Therefore, a new method of producing the 18 Ne isotope has been developed and tested giving good production rates. The baseline presented for the Beta Beam is therefore now to use the 6 He and 18 Ne isotopes for neutrino production. A 60 GHz ECRIS prototype, the first in the world, was developed and tested with contributions from EUROnu. The Beta Beam has to take into account the modifications of the injectors planned in view of LHC-upgrades. The Decay Ring lattices for the 8 Li and 8 B have been developed, the lattice for 6 He and 18 Ne has been optimized also to ensure the high intensity ion beam stability.
The discovery that the neutrino changes flavor as it travels through space has implications for t... more The discovery that the neutrino changes flavor as it travels through space has implications for the Standard Model of particle physics (SM)[1]. To know the contribution of neutrinos to the SM, needs precise measurements of the parameters governing the neutrino oscillations. This will require a high intensity beam-based neutrino oscillation facility. The EUROν Design Study will review three currently accepted methods of realizing this facility (the so-called Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance, will give means to the European research authorities to make a decision on the lay-out and construction of the future European neutrino oscillation facility. ”Beta Beams” produce collimated pure electron neutrino and antineutrino beams by accelerating beta active ions to high energies and letting them decay in a race-track shaped storage ring. EUROν Beta Beams are based on CERNs infrastructure and the fact tha...
The experimental study of the pulsed-mode operation of the PHOENIX-V2 electron cyclotron resonanc... more The experimental study of the pulsed-mode operation of the PHOENIX-V2 electron cyclotron resonance ion source at 28 GHz has clearly demonstrated, when increasing the repetition rate of the high-frequency power injection at frequencies higher than 1 Hz, the reality of a transient current peak occurring at the very beginning of the plasma discharge. This regime was named Preglow as an explicit reference to the classical Afterglow occurring at the microwave pulse end. After the transient Preglow peak, the plasma regime relaxes to the classical steady-state one. Experimental argon pulses for charge states from 2+ to 8+ are presented. The current observed during the Preglow peak can reach intensities on the order of 1 mA for low charge states (Ar4+). A zero-dimension theoretical model of electron cyclotron resonance (ECR) gas breakdown in a magnetic trap is presented in detail. Results of the simulation are compared with the experimental Preglow peaks and discussed.
Validation with an aluminium prototype___________________________________________ 3.3 Fabrication... more Validation with an aluminium prototype___________________________________________ 3.3 Fabrication of the ECRIS prototype _______________________________________ 3.3.1 Thermal calculations in helices __________________________________________________ 3.3.2 Engineering design ___________________________________________________________ 3.4 The future test bench ____________________________________________________ 3.4.1 Bending Magnet for the 60 GHz bench____________________________________________ 3.4.2 The 60 GHz Gyrotron _________________________________________________________ 3.4.3 On-site installation for the half-magnetic field test ___________________________________ 4 Planning _____________________________________________________________ 5 References____________________________________________________________ Related publications and communications ______________________________________
Physical Review Special Topics - Accelerators and Beams
The EUROnu project has studied three possible options for future, high intensity neutrino oscilla... more The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fr\'ejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of {\mu}+ and {\mu}- beams in a storage ring. The far detector in this case is a 100 kt Magnetised Iron Neutrino Detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular 6He and 18Ne, also stored in a ring. The far detector is also the MEMPHYS detector in the Fr\'ejus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Base...
The efficient production of short pulses of radioactive ion beams is a key point of the long term... more The efficient production of short pulses of radioactive ion beams is a key point of the long term CERN betabeam project. A strong R&D effort in the field of ion sources is required to reach this challenging objective. A summary of the pulsed beta-beam ion source specification is proposed. A discussion follows on the ion source technologies suitable for this demanding project. The proposed solution foreseen (a 60 GHz ECRIS), uses a cusp magnetic configuration based on water cooled copper coils. The 3D magnetic field structure, along with the mechanical design status is presented. An experimental test with an aluminium prototype shows a good agreement with simulation and validates the design. THE BETA-BEAM PROJECT The neutrino physicist community is currently discussing the next generation neutrino beam factory. Nowadays, several projects are still under competition. The Beta-Beam is a project studied by the CERN [1]. The baseline scenario is to generate, ionize, and then accelerate R...
In microwave plasmas with the presence of a magnetic field, fast electrons could result from coll... more In microwave plasmas with the presence of a magnetic field, fast electrons could result from collisionless energy absorption under electron cyclotron resonance (ECR) conditions. In this case, electrons are trapped between the two poles of the magnetic field and rotate at the cyclotron frequency ωce. When crossing a zone where the cyclotron frequency equals the microwave frequency (ωce=ω), electrons see a steady electric field in their reference frame and are constantly accelerated by the right handed polarized (RHP) wave. When the plasma density reaches the so-called critical density nc at which ω2pe=ω2±ωωce, where ωpe is the plasma electron frequency, the left handed polarized (LHP) electromagnetic wave can excite electrostatic waves that can produce collisionless electron heating and fast electron generation by Landau damping. In this study, a combination of the Langmuir probe and trace rare gas optical emission spectroscopy (TRG-OES) is used to analyze the electron energy probability function (EEPF) in microwave (2.45 GHz) low-pressure argon plasmas excited at ECR in a dipolar magnetic field. While both TRG-OES and Langmuir probe measurements agree on the effective electron temperature (TAlle) from 1.6 to 50 mTorr, TRG-OES, which is more sensitive to high energy electrons, shows that the EEPF is the sum of two Maxwellian populations: one described by TAlle and a high energy tail characterized by a temperature TTaile. Spatially resolved-TRG-OES measurements show that the high-energy tail (TTaile) in the EEPF is spatially localized near the magnet, while the effective electron temperature (TAlle) stays constant. The ratio between the high energy tail and the effective temperatures is found to increase with the absorbed microwave power and decrease with increasing pressure. The former phenomenon is ascribed to a rise in ECR heating due to a stronger RHP wave electric field and to an enhanced absorption of the LHP waves. On the other hand, the decrease in the ratio is attributed to a smaller magnetic confinement of the electrons (increase in the collision frequency), which lessens ECR heating and to a decrease in the LHP field intensity at the resonant position, which impedes the conversion into electrostatic waves.
Journal of Microwave Power and Electromagnetic Energy, 2017
ABSTRACT In connection with recently published results, two 2.45 GHz microwave plasma sources wer... more ABSTRACT In connection with recently published results, two 2.45 GHz microwave plasma sources were designed: a coaxial electron cyclotron resonance-type operating between 0.01 and 10 Pa and a collisional-type for higher pressure range, 1–100 Pa. The primary goal was to build self-matched plasma sources, which can maintain low reflected power levels without any impedance matching component. The microwave field was supplied to each plasma source via a coaxial feed from a solid-state microwave generator with adjustable power between 0 and 200 W and adjustable frequency from 2.4 to 2.5 GHz. The adjustable frequency of the generator is intended to be used as backup matching means if the reflected power increases above a set value; an automatic adjustment loop enables the microwave generator to start sweeping the frequency band until the lowest reflected power level is found. The modelling method used to obtain self-adapted plasma sources is explained; the performance of each source is evaluated by measuring the efficiency of the microwave power transmitted inside the plasma vs. gas pressure, gas type and microwave forward power level. Results of plasma source testing in industrial applications such as nanocrystalline diamond deposition on 4 inch silicon wafers and stainless steel nitriding are presented.
Il est très important pour moi de rédiger ces quelques lignes pour remercier les nombreuses perso... more Il est très important pour moi de rédiger ces quelques lignes pour remercier les nombreuses personnes qui ont permis ce travail. En effet, que ce soit mon entourage scientifique, familial ou mon cercle d'amis, tous ont influencés mon travail, directement ou plus subrepticement. Je tiens à remercier en premier lieu Christian Trassy, Directeur de Recherche et Yves Fautrelle, Professeur, directeurs successifs du laboratoire EPM, pour m'avoir accueilli dans leur laboratoire. Je remercie également Eric Beaugon, Maître de Conférence et directeur du CRETA, pour nous avoir hébergé dans son laboratoire la première année de ma thèse. Mes remerciements s'adressent aussi à Johann Collot, Professeur et directeur du LPSC, pour avoir accueilli notre équipe, le Centre de Recherche Plasma-Matériaux-Nanostructures (CRPMN), dans son laboratoire. Je dois beaucoup à la commission Européenne, qui grâce au projet MATECO (contrat STRP 505928), a apporté une grande partie des moyens consacrés à mes travaux de thèse, et je l'en remercie vivement. J'adresse mes remerciements aux membres du jury de ma thèse, tout d'abord à Caroline Boisse-Laporte, Chargée de Recherche, et Yvan Ségui, Directeur de Recherche, pour le dur travail de rapporteur qu'ils ont dû accomplir. Je remercie doublement Yves Pauleau, Professeur, d'avoir accepté d'être président du jury et de m'avoir formé lors de mon DEA. Merci aussi à Michel Touzeau, Directeur de Recherche, pour avoir accepté d'être membre du jury et pour le temps qu'il m'a consacré pour tenter de comprendre mes plasmas d'oxygène. Je remercie également Agnès Granier d'avoir accepté d'être membre de mon jury et pour les corrections judicieuses qu'elle a suggérées pour ma thèse. J'adresse des remerciements très particuliers à Ana Lacoste, Professeur et directeur de ma thèse, pour ses conseils, son soutien tout au long de ma thèse, la confiance qu'elle m'a accordée et ses idées lumineuses qui m'ont permis d'avancer lorsque tout espoir semblait perdu. J'exprime aussi toute ma gratitude envers Jacques Pelletier, Directeur de Recherche, directeur du CRPMN et co-directeur de ma thèse, pour ses conseils avisés, son optimisme qui permet toujours de faire avancer l'équipe, pour les orientations qu'il a pu me donner et pour m'avoir proposé cette thèse. Mes remerciements s'adressent aussi à Michel Moisan, Professeur et directeur du Groupe de Physique des Plasmas de l'Université de Montréal, pour m'avoir accueilli au sein de son équipe durant un mois pour modéliser mon plasma. Bien entendu, je remercie aussi Kremena Makasheva, Docteur, sans qui la modélisation n'aurait pas été possible et pour le temps qu'elle y a consacré, je la remercie également pour sa bonne humeur, son humour et pour m'avoir sorti au Canada sans quoi je me serais sévèrement ennuyé.
Final report on bunched efficiency of proposed high frequency ECR source for production of radioa... more Final report on bunched efficiency of proposed high frequency ECR source for production of radioactive isotopes needed for beta beam
Microwaves are frequently used to produce high density plasmas for industrial and laboratory appl... more Microwaves are frequently used to produce high density plasmas for industrial and laboratory applications, because they present several advantages when compared to radio-frequency discharges and discharges created using electrodes. Stable and reliable microwave plasma equipment based on magnetrons, and designed for automatic control of the operating parameters has already proved its efficiency in low temperature diamond deposition, exhaust gas abatement, thin-film deposition, etc. However, larger-scale processing with high density and uniform plasma is mandatory for surface treatments to get uniform etching or deposition rates. To meet these industrial requirements AuraWave, an ECR microwave plasma source operating in the 10-2–1 Pa pressure range, and Hi-Wave, a collisional plasma source for higher pressure gas processing (i.e. 1 – 100 Pa) have been designed. Furthermore, because each plasma source is powered by its own microwave solid-state generator, multiple sources operating in ...
2017 IEEE International Conference on Plasma Science (ICOPS), 2017
Large scale industrial processes for surface treatment require uniform, dense, and quiescent plas... more Large scale industrial processes for surface treatment require uniform, dense, and quiescent plasma. One of the strategies in achieving this latter consists in distributing several microwave applicators forming a 2D or 3D network configuration 1, which permits plasma density exceeding the critical density $n_{c}$defined by $n_{c}=\omega _{0}^{2}m_{e}\varepsilon _{0}/e^{2}$with $\omega _{0}$the microwave angular frequency, $\varepsilon _{0}$the vacuum permittivity and $m_{e}$the mass of the electron. Furthermore, integrating microwave applicators designed without any need of complicated matching system proved to be interesting in order to achieve fine tuning of the plasma spatial distribution, hence uniform and dense plasma over large area 2.
LPSC has developed a 60 GHz Electron Cyclotron Resonance (ECR) Ion Source prototype called SEISM.... more LPSC has developed a 60 GHz Electron Cyclotron Resonance (ECR) Ion Source prototype called SEISM. The magnetic structure uses resistive polyhelix coils designed in collaboration with the French National High Magnetic Fields Facility (LNCMI) to produce a CUSP magnetic configuration. A dedicated test bench and appropriate electrical and water cooling environments were built to study the validity of the mechanics, the thermal behaviour and magnetic field characteristics obtained at various current intensities. During the last months, measurements were performed for several magnetic configurations, with up to 7000 A applied on the injection and extraction coils sets. The magnetic field achieved at 13000 A is expected to allow 28 GHz ECR condition, so by extrapolation 60 GHz should be possible at about 28000 A. However, cavitation issues that appeared around 7000 A are to be solved before carrying on with the tests. This contribution will recall some of the crucial steps in the prototype...
High-density reactive species plasmas uniformly covering large surface areas are required for sem... more High-density reactive species plasmas uniformly covering large surface areas are required for semi-conductor processing. Novel, self-matched plasma sources using microwave solid state generators have been developed for this purpose. The technology applied, based on automatic frequency tuning, allowed to eliminate the impedance matching system. Large surface plasmas have been achieved by using a distribution of elementary sources. A big campaign of plasma density measurement using a Langmuir probe has allowed to create a database for different plasma conditions for a single source. Thanks to an internally developed software, the density obtained with several sources in various distribution configurations has been simulated. The position and the power of each source have been optimized and the calculations have been validated by experimental measurements. High plasma densities >1011 cm−3 over large areas >400 mm in diameter with only 13 plasma sources have been achieved with all...
A careful study of pulsed mode operation of the PHOENIX ECR ion source has clearly demonstrated t... more A careful study of pulsed mode operation of the PHOENIX ECR ion source has clearly demonstrated the reality of an unexpected transient current peak, occurring at the very beginning of the plasma breakdown. This regime was named the Preglow, as an explicit reference to the Afterglow occurring at the microwave pulse end. After the transient Preglow peak, the plasma regime relaxes to the classical steady state one. Argon Preglow experiments performed at LPSC are presented. A theoretical model of ECR gas breakdown in a magnetic trap, developed at IAP, showing satisfactory agreement with the experimental results is suggested. Corresponding Author : [email protected]
Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta... more Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta Beam has outstanding capabilities to contribute to precision measurements of the parameters governing neutrino oscillations. The FP7 collaboration EUROnu (2008-2012) is a design study that will review three facilities (Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance, will give means to the European research authorities to make decisions on future European neutrino oscillation facilities. "Beta Beams" produce collimated pure electron (anti)neutrinos by accelerating beta active ions to high energies and having them decay in a storage ring. Using existing machines and infrastructure is an advantage for the cost evaluation; however, this choice is also constraining the Beta Beams. Recent work to make the Beta Beam facility a solid option will be described: production of Beta Beam isotopes, the 60 GHz pulsed E...
choice is also constraining the Beta Beams. The isotope pair of choice for the Beta Beam is 6 He ... more choice is also constraining the Beta Beams. The isotope pair of choice for the Beta Beam is 6 He and 18 Ne. However before the EUROnu studies one of the needed isotopes, 18 Ne, could not be produced in rates that satisfy the needs for physics reach of the Beta Beam. Therefore, studies of alternative beta emitters, 8 Li and 8 B, with properties interesting for a Beta Beam have been proposed and have been studied within EUROnu. These alternative isotopes could be produced by using a small storage ring, in which the beam traverses a target, creating the 8 Li and 8 B isotopes. This Production Ring, the injection Linac and the target system have been evaluated. Measurements of the cross-section of the reactions to produce the Beta Beam isotopes show interesting results. A device to collect the produced isotopes from the target has been developed and tested. However, the obtained rates of the 8 Li and 8 B, using the Production Ring for production of 8 Li and 8 B, is not yet, according to simulations, giving the rates of isotopes that would be needed. Therefore, a new method of producing the 18 Ne isotope has been developed and tested giving good production rates. The baseline presented for the Beta Beam is therefore now to use the 6 He and 18 Ne isotopes for neutrino production. A 60 GHz ECRIS prototype, the first in the world, was developed and tested with contributions from EUROnu. The Beta Beam has to take into account the modifications of the injectors planned in view of LHC-upgrades. The Decay Ring lattices for the 8 Li and 8 B have been developed, the lattice for 6 He and 18 Ne has been optimized also to ensure the high intensity ion beam stability.
The discovery that the neutrino changes flavor as it travels through space has implications for t... more The discovery that the neutrino changes flavor as it travels through space has implications for the Standard Model of particle physics (SM)[1]. To know the contribution of neutrinos to the SM, needs precise measurements of the parameters governing the neutrino oscillations. This will require a high intensity beam-based neutrino oscillation facility. The EUROν Design Study will review three currently accepted methods of realizing this facility (the so-called Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance, will give means to the European research authorities to make a decision on the lay-out and construction of the future European neutrino oscillation facility. ”Beta Beams” produce collimated pure electron neutrino and antineutrino beams by accelerating beta active ions to high energies and letting them decay in a race-track shaped storage ring. EUROν Beta Beams are based on CERNs infrastructure and the fact tha...
The experimental study of the pulsed-mode operation of the PHOENIX-V2 electron cyclotron resonanc... more The experimental study of the pulsed-mode operation of the PHOENIX-V2 electron cyclotron resonance ion source at 28 GHz has clearly demonstrated, when increasing the repetition rate of the high-frequency power injection at frequencies higher than 1 Hz, the reality of a transient current peak occurring at the very beginning of the plasma discharge. This regime was named Preglow as an explicit reference to the classical Afterglow occurring at the microwave pulse end. After the transient Preglow peak, the plasma regime relaxes to the classical steady-state one. Experimental argon pulses for charge states from 2+ to 8+ are presented. The current observed during the Preglow peak can reach intensities on the order of 1 mA for low charge states (Ar4+). A zero-dimension theoretical model of electron cyclotron resonance (ECR) gas breakdown in a magnetic trap is presented in detail. Results of the simulation are compared with the experimental Preglow peaks and discussed.
Validation with an aluminium prototype___________________________________________ 3.3 Fabrication... more Validation with an aluminium prototype___________________________________________ 3.3 Fabrication of the ECRIS prototype _______________________________________ 3.3.1 Thermal calculations in helices __________________________________________________ 3.3.2 Engineering design ___________________________________________________________ 3.4 The future test bench ____________________________________________________ 3.4.1 Bending Magnet for the 60 GHz bench____________________________________________ 3.4.2 The 60 GHz Gyrotron _________________________________________________________ 3.4.3 On-site installation for the half-magnetic field test ___________________________________ 4 Planning _____________________________________________________________ 5 References____________________________________________________________ Related publications and communications ______________________________________
Physical Review Special Topics - Accelerators and Beams
The EUROnu project has studied three possible options for future, high intensity neutrino oscilla... more The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fr\'ejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of {\mu}+ and {\mu}- beams in a storage ring. The far detector in this case is a 100 kt Magnetised Iron Neutrino Detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular 6He and 18Ne, also stored in a ring. The far detector is also the MEMPHYS detector in the Fr\'ejus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Base...
The efficient production of short pulses of radioactive ion beams is a key point of the long term... more The efficient production of short pulses of radioactive ion beams is a key point of the long term CERN betabeam project. A strong R&D effort in the field of ion sources is required to reach this challenging objective. A summary of the pulsed beta-beam ion source specification is proposed. A discussion follows on the ion source technologies suitable for this demanding project. The proposed solution foreseen (a 60 GHz ECRIS), uses a cusp magnetic configuration based on water cooled copper coils. The 3D magnetic field structure, along with the mechanical design status is presented. An experimental test with an aluminium prototype shows a good agreement with simulation and validates the design. THE BETA-BEAM PROJECT The neutrino physicist community is currently discussing the next generation neutrino beam factory. Nowadays, several projects are still under competition. The Beta-Beam is a project studied by the CERN [1]. The baseline scenario is to generate, ionize, and then accelerate R...
In microwave plasmas with the presence of a magnetic field, fast electrons could result from coll... more In microwave plasmas with the presence of a magnetic field, fast electrons could result from collisionless energy absorption under electron cyclotron resonance (ECR) conditions. In this case, electrons are trapped between the two poles of the magnetic field and rotate at the cyclotron frequency ωce. When crossing a zone where the cyclotron frequency equals the microwave frequency (ωce=ω), electrons see a steady electric field in their reference frame and are constantly accelerated by the right handed polarized (RHP) wave. When the plasma density reaches the so-called critical density nc at which ω2pe=ω2±ωωce, where ωpe is the plasma electron frequency, the left handed polarized (LHP) electromagnetic wave can excite electrostatic waves that can produce collisionless electron heating and fast electron generation by Landau damping. In this study, a combination of the Langmuir probe and trace rare gas optical emission spectroscopy (TRG-OES) is used to analyze the electron energy probability function (EEPF) in microwave (2.45 GHz) low-pressure argon plasmas excited at ECR in a dipolar magnetic field. While both TRG-OES and Langmuir probe measurements agree on the effective electron temperature (TAlle) from 1.6 to 50 mTorr, TRG-OES, which is more sensitive to high energy electrons, shows that the EEPF is the sum of two Maxwellian populations: one described by TAlle and a high energy tail characterized by a temperature TTaile. Spatially resolved-TRG-OES measurements show that the high-energy tail (TTaile) in the EEPF is spatially localized near the magnet, while the effective electron temperature (TAlle) stays constant. The ratio between the high energy tail and the effective temperatures is found to increase with the absorbed microwave power and decrease with increasing pressure. The former phenomenon is ascribed to a rise in ECR heating due to a stronger RHP wave electric field and to an enhanced absorption of the LHP waves. On the other hand, the decrease in the ratio is attributed to a smaller magnetic confinement of the electrons (increase in the collision frequency), which lessens ECR heating and to a decrease in the LHP field intensity at the resonant position, which impedes the conversion into electrostatic waves.
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Papers by L. Latrasse