Author: Thuillier, T.
Paper Title Page
TUWZO04
Influences of Magnetic Field Parameters to ECRIS Plasma Characteristics  
 
  • J.B. Li, J.W. Guo, D. Hitz, L.B. Li, L.X. Li, W. Lu, L.T. Sun, X.Z. Zhang, H.W. Zhao, H. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
  • B.S. Bhaskar, T. Thuillier
    LPSC, Grenoble Cedex, France
  • B.S. Bhaskar, H.A. Koivisto, O.A. Tarvainen, V. Toivanen
    JYFL, Jyväskylä, Finland
  • O.A. Tarvainen
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  To investigate the hot electron population and the appearance of kinetic instabilities in ECRIS plasma, the axially emitted bremsstrahlung spectra and microwave bursts emitted from ECRIS plasma were synchronously measured on SECRAL-II ion source with various magnetic field configurations. The experimental results show that when Bmin/Becr is less than ~0.8, the spectral temperature Ts increases linearly with the Bmin/Becr-ratio when the injection, extraction and radial mirror fields are kept constant. Above this threshold Ts saturates and the electron cyclotron instability appears simultaneously. This study has also demonstrated that Ts decreases linearly with the increase of the average gradient over the ECR surface when the on-axis gradient and hexapole field strengths are constant. In addition, it is found that Ts decreases with the increase of the gradient at the resonance zone at relatively low mirror ratio and is insensitive to the gradient at high mirror ratio when Bmin is constant. Compared to a recent study taken on a fully superconducting ECRIS, this study shows different results discussing the mechanisms behind the correlation of magnetic field parameters to Ts.  
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TUXZO03 Angular Distribution Measurement of Atoms Evaporated from a Resistive Oven Applied to Ion Beam Production 72
 
  • T. Thuillier, A. Leduc
    LPSC, Grenoble Cedex, France
  • O. Bajeat, A. Leduc, L. Maunoury
    GANIL, Caen, France
 
  A low temperature oven has been developed to produce calcium beam with Electron Cyclotron Resonance Ion Source. The atom flux from the oven has been studied experimentally as a function of the temperature and the angle of emission by means of a quartz microbalance. The absolute flux measurement permitted to derive Antoine’s coefficient for the calcium sample used : A=8.98± 0.07 and B=7787± 110 in standard unit. The angular FWHM of the atom flux distribution is found to be 53.7±7.3 °at 848K. The atom flux hysteresis observed experimentally in several laboratories is explained as follows: at first calcium heating, the evaporation comes from the sample only resulting in a small evaporation rate. once a full calcium layer has formed on the crucible refractory wall, the caclcium evaporation surface includes the crucible’s enhancing dramatically the evaporation rate for a givent temperature. A Monte-Carlo code, developed to reproduce and investigate the oven behaviour as a function of temperature is presented. A discussion on the gas regime in the oven is proposed as a function of its temperature. A fair agreement between experiment and simulation is found.  
slides icon Slides TUXZO03 [4.542 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUXZO03  
About • Received ※ 28 September 2020 — Revised ※ 19 February 2021 — Accepted ※ 21 July 2021 — Issue date ※ 16 April 2022
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TUYZO02 A Guiding Centre Approximation Approach for Simulation Electron Trajectories in ECR and Microwave Ion Sources 84
 
  • J.A. Méndez, T. Thuillier
    LPSC, Grenoble Cedex, France
  • T. Minea
    CNRS LPGP Univ Paris Sud, Orsay, France
 
  Funding: Work supported by the CNRS under the 80|PRIME grant
This work presents a study on the feasibility of the implementation of the guiding centre (GC) approach in electron cyclotron resonance (ECR) ion sources, with the goal of speeding up the electron’s orbit integration in certain regimes. It is shown that the GC approximation reproduces accurately the trajectory drifts and periodic behaviour of electrons in the minimum-B field. A typical electron orbit far enough from the source’s axis is well reproduced for 1 µs of propagation time, with the GC time-step constrained below 100 ps, giving one order of magnitude gain in computation time with respect to Boris. For an electron orbit close to the axis a disphasement of the electron’s trajectory is observed, but the spatial envelope is conserved. A comparative study analyses electron trajectories in a flatter B-field, that in a microwave discharge ion source, where this method’s drawbacks may be avoided given a smaller magnetic field gradient and a shorter electron lifetime in the plasma chamber. In this regime electron trajectories were very well reproduced by the GC approximation. The time-step was constrained below 10 ns, providing up to 30 times faster integration compared to Boris.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUYZO02  
About • Received ※ 28 September 2020 — Revised ※ 21 December 2020 — Accepted ※ 18 May 2021 — Issue date ※ 02 February 2022
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TUZZO02 Electron Cyclotron Resonance Ion Source Related Research and Development Work at the Department of Physics, University of Jyväskylä (JYFL) 98
 
  • H.A. Koivisto, B.S. Bhaskar, A. Ikonen, T. Kalvas, S.T. Kosonen, R.J. Kronholm, M.S.P. Marttinen, O.P.I. Timonen, V. Toivanen
    JYFL, Jyväskylä, Finland
  • J. Angot, B.S. Bhaskar, T. Thuillier
    LPSC, Grenoble Cedex, France
  • I. Izotov, V. Skalyga
    IAP/RAS, Nizhny Novgorod, Russia
  • L. Maunoury
    GANIL, Caen, France
  • O.A. Tarvainen
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Funding: The work has received funding from the Academy of Finland under the Academy of Finland Project funding (No. 315855) and from University Grenoble Alps under EMERGENCE-project.
Recent research work of the JYFL ion source team covers multi-diagnostic studies of plasma instabilities, high-resolution plasma optical emission spectroscopy, ion current transient measurements to define the total life-time of a particle in the highly charged plasma. The JYFL team also elaborates the magnetic and technical design of the unconventional ion source named CUBE. The R&D work includes, in addition, the commissioning and operation of the high-performance 18 GHz ECRIS, HIISI. The instability measurements have revealed new information about the parameters affecting the onset of the plasma instabilities and shown that different instability modes exist. The ion-beam transient studies have given information about the cumulative life-time of highly-charged ions convergent with the ion temperatures deduced from the Doppler broadening of emission lines. The CUBE prototype has a minimum-B quadrupole magnetic field topology, similar to ARC-ECRIS, and its all-permanent magnet structure has been optimized for 10 GHz frequency. The CUBE design will be presented along with its commissioning status. The status and operational experience with HIISI will be reported as well.
 
slides icon Slides TUZZO02 [9.553 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUZZO02  
About • Received ※ 28 September 2020 — Revised ※ 09 November 2020 — Accepted ※ 03 December 2020 — Issue date ※ 05 May 2021
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TUZZO03
Study on the Correlation between Energy Distribution of Electrons Lost from the Confinement and Plasma Bremsstrahlung on a min-B ECR Plasmas  
 
  • B.S. Bhaskar, T. Thuillier
    LPSC, Grenoble Cedex, France
  • B.S. Bhaskar, T. Kalvas, H.A. Koivisto, R.J. Kronholm, M.S.P. Marttinen, O.A. Tarvainen, V. Toivanen
    JYFL, Jyväskylä, Finland
  • I. Izotov, V. Skalyga
    IAP/RAS, Nizhny Novgorod, Russia
  • O.A. Tarvainen
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Funding: The work has received funding from the Academy of Finland under the Academy of Finland Project funding (No. 315855) and from University Grenoble Alps under EMERGENCE-project.
The study of plasma bremsstrahlung has been used as a diagnostic tool for understanding the behavior of confined plasma in Electron Cyclotron Resonance Ion Sources (ECRIS). In order to understand the relation connecting the confined plasma and the electrons escaping the confinement, a series of measurements have been made to measure the bremsstrahlung produced in the axial and radial direction along with the Lost Electron Energy Distribution (LEED) axially on JYFL 14 GHz ECR. We present here the effect of various source parameters on the axial and radial bremsstrahlung along with the LEED on a min-B confined ECR plasma. The measured LEED has been found to show a correlation with bremsstrahlung measurement and also have observed as a potential diagnostic method for instability. The explanation for observed LEED and bremsstrahlung trends is provided.
 
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TUZZO04 Status of the 60 GHz ECR Ion Source Research 102
 
  • T. André, J. Angot, M.A. Baylac, P. Sole, T. Thuillier
    LPSC, Grenoble Cedex, France
  • F. Debray
    GHMFL, Grenoble, France
  • I. Izotov, V. Skalyga
    IAP/RAS, Nizhny Novgorod, Russia
 
  SEISM is a compact ECR ion source operating at 60 GHz developed up to 2014. The prototype uses a magnetic cusp to confine the plasma. This simple magnetic geometry was chosen to allow the use of polyhelix coils (developed at the LNCMI, Grenoble) to generate a strong magnetic confinement featuring a closed ECR surface at 2.1 T. The plasma is sustained by a 300 kW microwave pulse of 1 ms duration and with a 2 Hz repetition rate. Previous experiments at LNCMI have successfully demonstrated the establishment of the nominal magnetic field and the extraction of ion beams with a current density up to ~ 1A/cm2. The presence of "afterglow" peaks was also observed, proving the existence of ion confinement in a cusp ECR ion source. The last run was prematurely stopped but the project restarted in 2018 and new experiments are planned in 2021. A new transport beam line has been designed to improve ion beam transport towards the beam detectors. Short- and long-term research plans are presented, including numerical simulations of the beam transport line and future upgrades of the ion source with the main goal to transform the high current density measured into a real high intensity ion beam.  
slides icon Slides TUZZO04 [5.933 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUZZO04  
About • Received ※ 28 September 2020 — Revised ※ 15 January 2021 — Accepted ※ 14 February 2021 — Issue date ※ 14 July 2022
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WEZZO02 Contaminants Reduction in ECR Charge Breeders by LNL LPSC GANIL Collaboration 151
 
  • J. Angot, M.A. Baylac, M. Migliore, P. Sole, T. Thuillier
    LPSC, Grenoble Cedex, France
  • A. Galatà
    INFN/LNL, Legnaro (PD), Italy
  • L. Maunoury
    GANIL, Caen, France
 
  Contaminants reduction in Electron Cyclotron Resonance Charge Breeders (ECRCB) is a key point for the future experiments foreseen at LNL and GANIL Isotope Separation On Line (ISOL) facilities. According to the mass separator resolution set downstream the ECRCB, the radioactive ion beam study can be challenged in case of low production rate. An ongoing collaboration between LNL, LPSC and GANIL laboratories aims to improve the beam purity, acting on all the pollutant causes. Comparative experiments will be done at LPSC using different techniques, like covering the plasma chamber wall with liners of different materials. Different configurations of the ECRCB will also be tested, with the enhancement of the efficiency and charge breeding time parameters as additional objectives. A presentation of this program is proposed together with the recent upgrade of the LPSC 1+N+ test bench, with the aim to improve the vacuum quality.  
slides icon Slides WEZZO02 [1.915 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-WEZZO02  
About • Received ※ 29 September 2020 — Revised ※ 01 October 2020 — Accepted ※ 15 October 2020 — Issue date ※ 04 November 2020
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