Author: Guo, J.W.
Paper Title Page
MOWZO01 FECR Ion Source Development and Challenges 1
 
  • L.T. Sun, Y. Chen, M.Z. Guan, J.W. Guo, J.B. Li, L.B. Li, L.X. Li, W. Lu, E.M. Mei, X.J. Ou, Z. Shen, X.D. Wang, B.M. Wu, W. Wu, C.J. Xin, X.Z. Zhang, H.W. Zhao, S.J. Zheng, L. Zhu
    IMP/CAS, Lanzhou, People’s Republic of China
  • Z. Shen, L.T. Sun
    UCAS, Beijing, People’s Republic of China
 
  FECR or the First 4th generation ECR ion source is under development at Institute of Modern Physics (IMP) since 2015. This ion source is aiming to extract intense highly charged heavy ion beams in the order of emA from the dense plasma heated with 45 GHz microwave power. To provide effective magnetic confinement to the 45 GHz ECR plasma, a state of the art Nb3Sn magnet with min-B configuration is a straightforward technical path. As there is no much precedent references, it has to be designed, prototyped at IMP through in-house development. Meanwhile, other physics and technical challenges to a 4th generation ECR ion source are also tackled at IMP to find feasible solutions. This paper will give a brief review of the critical issues in the development of FECR ion source. A detailed report on the status of FECR prototype magnet development will be presented.  
slides icon Slides MOWZO01 [16.578 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOWZO01  
About • Received ※ 27 September 2020 — Revised ※ 02 October 2020 — Accepted ※ 30 November 2020 — Issue date ※ 07 August 2021
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MOWZO02 LECR5 Development and Status Report 6
 
  • C. Qian, J.R. An, J.J. Chang, X. Fang, Y.C. Feng, J.W. Guo, Z.H. Jia, L.B. Li, W. Lu, J.D. Ma, Y.M. Ma, L.T. Sun, H. Wang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
  • C. Qian
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  LECR5 (Lanzhou Electron Cyclotron Resonance ion source No. 5) is an 18 GHz room temperature ECR ion source featuring Ø80 mm ID (Internal Diameter) plasma chamber and high magnetic fields. It has been successfully constructed at IMP recently and has been fully commissioned to meet the requirements of SESRI (Space Environment Simulation and Research Infrastructure) project. According to the test results, LECR5 can meet the requirements of SESRI with sufficient beam intensities within the required the transverse emittances. As LECR5 is designed to be optimal for the operation at 18 GHz, we have managed to explore the source performance at 18 GHz with a maximum microwave power around 2 kW. Recent source test indicates, LECR5 can produce not only high intensity ion beams such as 2.12 emA O6+, 121 e’A of Ar14+, 73 e’A of Kr23+, 145 e’A of Xe27+, but also very high charge state ion beams such as 22 e’A of Bi41+. This paper will present the recent progress with LECR5, especially the intense ion beam production and the beam quality investigation.  
slides icon Slides MOWZO02 [5.886 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOWZO02  
About • Received ※ 27 September 2020 — Revised ※ 30 December 2020 — Accepted ※ 18 May 2021 — Issue date ※ 14 November 2021
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TUWZO02
Tentative Solution to Plasma Chamber Cooling for High Power ECR Ion Source Operation  
 
  • J.W. Guo, Y.C. Feng, D. Hitz, W. Huang, J.B. Li, L.B. Li, L.X. Li, W. Lu, J.D. Ma, L.T. Sun, Y.Y. Yang, W.H. Zhang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
  • W. Huang, L.T. Sun
    UCAS, Beijing, People’s Republic of China
 
  High charge state electron cyclotron resonance ion source (ECRIS) is characterized by a so-called min-B magnetic field configuration, which provokes the localized plasma over-heating to plasma chamber especially for the 3rd generation ECRISs at high power operation condition. With the increase of rf power, more plasma energy will be dumped to tiny areas and result in a very high localized power density, which is estimated to be up to 1 kW/cm2. Few existing ECR plasma chamber cooling designs can withstand such high heat fluxes. In this paper, we report a new plasma chamber cooling design with so-called Micro-channel cooling technology, which can not only realize efficient heat transfer, but also retains a small radial thickness that is beneficial for the radial magnetic field. In order to evaluate the performance of the cooling structure with micro-channel design, experimental cooling loop for high heat flux has been designed and built at IMP. Initial experiments demonstrate that optimized configuration can achieve high heat flux cooling in the range of 1 kW/cm2 and beyond. Based on these results, a plasma chamber with micro-channel design for SECRAL has been designed and tested.  
slides icon Slides TUWZO02 [9.402 MB]  
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TUWZO03 Production of Metallic Ion Beams with Inductive Heating Oven at Institute of Modern Physics 65
 
  • W. Lu, Y.C. Feng, J.W. Guo, W. Huang, L.B. Li, L.X. Li, H.Y. Ma, J.D. Ma, C. Qian, L.T. Sun, W.H. Zhang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
  • W. Huang, L.T. Sun
    UCAS, Beijing, People’s Republic of China
  • C. Qian
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  A High-Temperature Oven (HTO) with inductive heating technology has been developed successfully in 2019 at Institute of Modern Physics. This oven features durable operation temperature of >2000’ inside the tantalum susceptor. By careful design the oven structure, material compatibility and thermal stress issues at high temperature has been successfully handled, which enables the production of >400 e’A U33+ with SECRAL-II*. With necessary refinement, this type of oven could also be available with room temperature ECR ion sources, like LECR4 and LECR5. Some improvements in structure have been proposed in this year. The design and testing results will be presented in this contribution.
*W. Lu, L. T. Sun, C. Qian, L. B. Li, J. W. Guo, W. Huang, X. Z. Zhang, and H. W. Zhao, Rev. Sci. Instrum. 90, 113318 (2019);
 
slides icon Slides TUWZO03 [7.369 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUWZO03  
About • Received ※ 28 September 2020 — Revised ※ 30 December 2020 — Accepted ※ 18 May 2021 — Issue date ※ 08 October 2021
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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.  
slides icon Slides TUWZO04 [4.062 MB]  
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WEWZO06
Observation of Cyclotron Instabilities in SECRAL-II Ion Source  
 
  • L.X. Li, Y.C. Feng, J.W. Guo, D. Hitz, J.B. Li, W. Lu, L.T. Sun, W.H. Zhang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Cyclotron instabilities in Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are related to non-linear interaction between plasma waves and energetic electrons, resulting in strong microwave emission, a burst of energetic electrons escaping the plasma, and the periodic oscillations of the extracted beam currents. Precedent investigation of cyclotron instabilities has proved that Bmin/BECR can be treated as a magnetic field threshold. Recently, experiments with SECRAL-II ion source demonstrate that Bmin/BECR is not the only knob, and other field parameters have also been found to be related to cyclotron instabilities, such as mirror ratio and radial field. Namely, the trigger of cyclotron instability is a combination of many magnetic field parameters. This paper will give the experimental setup at IMP for cyclotron instability investigations and experimental observations will be presented.  
slides icon Slides WEWZO06 [1.021 MB]  
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WEXZO01
High Intensity Ion Beam Extraction System for FECR  
 
  • Z. Shen, X. Fang, J.W. Guo, Z.H. Jia, Y.G. Liu, W. Lu, L.T. Sun, Y. Yang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
  • L.T. Sun
    UCAS, Beijing, People’s Republic of China
 
  To meet the beam requirements of High Intensity heavy ion Accelerator Facility (HIAF), the Institute of Modern Physics is developing a Fourth generation ECR ion source (FECR). Targeting at the operation frequency of 45 GHz, FECR is expected to produce very high intensity highly charged heavy ion beams, such as 1.0 emA 238U35+, 2 emA 78Kr19+, 10 emA 16O6+, etc. Based on the records with the 3rd generation ECR ion source operating at 24-28 GHz, the corresponding total drain current of FECR could reach 20-60 emA. To extract such high intensity multi-charged ion beams from the source with high beam quality and transmission efficiency, conventional diode or triode extraction system might not be suitable, and therefore a 4-electrode extraction system with a total extraction voltage of 50 kV is designed to mitigate the space charge influences and minimize the beam emittance growth in the extraction region. In this paper, a 3D model of the FECR extraction system is built using the IBSimu code. The electrode angles, voltages and electrode spacings are optimized for different ion beam conditions respectively. Beam properties comparison of various simulation conditions are presented.  
slides icon Slides WEXZO01 [7.712 MB]  
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