Author: Lu, W.
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MOA2
Extending the Performance of Venus Ion Source  
 
  • D. Xie, J.Y. Benitez, C.M. Lyneis, D.S. Todd
    LBNL, Berkeley, California, USA
  • W. Lu
    IMP/CAS, Lanzhou, People's Republic of China
 
  Continuing efforts to improve the VENUS performance, especially those started since 2014, have led to greatly enhanced source performance. Improved cooling of the plasma chamber and a slightly modified 28 GHz microwave coupling have resulted in reliable operations, increased injected power of up to 10 kW, and a substantial enhancement in VENUS overall performance. VENUS has produced the following ion beams: 600 eµA of 16O8+, 4 eµA of 40Ar18+, 17 eµA of 78Kr31+, 0.8 eµA of 124Xe45+, 0.6 eµA of 197Au58+ and 0.1 eµA of 209Bi61+. Compared to prior performance, ion beam intensity has increased up to a factor of 6 for the same high charge state and there has been an increase of five charge states upwards for Au and Bi beams where beam intensity is about 1 eµA. In addition a number of ultra-high charge state ion beams at lower intensities have been produced. With ion beams of 124Xe47+, 48+, 49+ injected from VENUS, the total beam energy has reached a new record of ~2.6 GeV for a K140 cyclotron. VENUS produced for the first time oxygen charge state distribution (CSD) peaking at O7+ which is a good step for VENUS and a milestone for ECRIS technology, indicating that there may still be room for improvements.  
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TUA5 High Power Operation with SECRAL-II Ion Source 58
 
  • L.T. Sun, X. Fang, J.W. Guo, W. Huang, J.B. Li, L. B. Li, L. X. Li, W. Lu, H.Y. Ma, Z. Shen, Y. Yang, W.H. Zhang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  SECRAL-II ion source has been successfully developed with the experiences from SECRAL that is another superconducting ECR ion source in operation at IMP. Other than that, SECRAL-II has been intentionally optimized in structure so as to make it optimum for 28 GHz microwave operation. This ion source was available on the test bench in early 2016, and has been used for 28 GHz high microwave power commissioning and tests. With a maximum power 10 kW@28 GHz and 2 kW@18 GHz, very high microwave power density and dense hot plasma could be built in the 5-liter volume plasma chamber. Consequently very high current density ion beams of high charge states are achievable, which have already exceeded the performance the 24 GHz SECRAL had made couple of years ago. However, there is also the intractable issues stemmed from the hot dense electrons inside the plasma, such as plasma chamber cooling, dynamic heat load to the cryogenic system, and so on. This paper will present the recent results of SECRAL-II operated with high microwave power. The typical consequent issues during the high power course other than high intensity high charge state ion beam production will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUA5  
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TUB1
Perspective on High-Power Microwave Coupling in Gyrotron Frequency ECR Ion Sources  
 
  • J.W. Guo, X. Fang, Y.C. Feng, L. B. Li, L. X. Li, W. Lu, Z. Shen, L.T. Sun, W.H. Zhang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  Better understanding of microwave power coupling is a key issue to enhance the performance of an ECR ion source in terms of higher ion beam intensity yield and critical in the design of the next generation ECRIS. For this reason, we investigated the impact on highly charged ion production using different microwave coupling modes and waveguide calibers with superconducting ECR Ion Source SECRAL, and some very encouraging results were obtained. Based on the comparison of ion source performance working at different coupling schemes, analytical studies on microwave power launching efficiency and the characteristics of electric field power distribution inside the ECRIS chamber have been made and some preliminary conclusions will be given in this paper. This paper will also provide a 45 GHz microwave solution for the next generation ECR ion source FECR (a Fourth generation ECR ion source). After off-line tests of microwave transmission efficiency and mode purity, the 45 GHz gyrotron microwave system has been commissioned with SECRAL-II (a superconducting ECR ion source optimized for 28 GHz operation), and some preliminary results have been achieved and will be given in this paper.  
slides icon Slides TUB1 [1.968 MB]  
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WEA2
Bremsstrahlung Measurements with SECRAL II Ion Source  
 
  • J.B. Li, J.W. Guo, L. B. Li, W. Lu, L.T. Sun, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  To investigate the hot electrons in highly charged electron cyclotron resonance (ECR) plasma, the bremsstrahlung spectra for X-rays between 10 and 300 keV were measured from SECRAL- II, a third-generation ECRIS at the Institute of Modern Physics. We focused on how the external source parameters, especially the magnetic configuration affect the axial bremsstrahlung and the resulting spectral temperature Ts. The experimental results have shown that Ts appears to be dependent solely on the minimum magnetic field Bmin rather than (Bmin/BECR) and the microwave frequency '. In addition, this investigation has shown that Ts is not sensitive to HV, bias and gas pressure, which implies that a more careful consideration into the heating mechanism of ECRIS is needed.  
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WEB3
High Temperature Oven Development for Intense Metal Beam Production at IMP  
 
  • W. Lu, W. Huang, C. Qian, L.T. Sun, X.Z. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
 
  As the main injector of heavy ion accelerator, ECR ion sources need to provide more and more intense highly charged refractory metallic ion beams at Institute of Modern Physics. This requires the performance of high temperature oven to be further improved so that the crucible can operate at ultra-high temperature for a long time without deformation. In order to meet these requirements, an inductive high temperature oven with ~200 kHz of heating frequency has been proposed and fabricated. The very preliminary off-line test results show that this oven can reach up to about 1800°C at 0.5 kW of AC power. In this contribution, we will discuss the structure of this high temperature oven and analyze the testing results as well.  
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THA4 Development of LECR4 Ion Source for Intense Beam Production and LECR5 for SESRI Project 188
 
  • C. Qian, X. Fang, Y.C. Feng, J.W. Guo, W. Huang, Z.H. Jia, X.X. Li, W. Lu, L.T. Sun, H. Wang, Y. Yang, X.Z. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  Several intense highly charged heavy ion beams have been produced from Lanzhou ECR ion source No.4 (LECR4) since 2014. Recently an attempt to generate intense light ion beam was tested by High-B mode of LECR4 ion source. We firstly produced 8.72 emA of 4He2+ beam with 1.7 kW of 18 GHz microwave power at 30 kV extraction voltage. According to the experience of LECR4. A new room temperature ECR ion source (named LECR5) has been designed to deliver multiple charge ion beams for the Space Environment Simulation Research Infrastructure (SESRI) at Harbin Institute of Technology. It aims to produce almost all ion beams from H2+ to 209Bi32+. This article reviews the latest result of LECR4 and preliminary design of LECR5 in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-THA4  
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