• J. Wei, Y.J. Bai, J.C. Cai, H. Chen, C. Cheng, Q. Du, T. Du, Q.X. Feng, Z. Feng, H. Gong, X. Guan, X.X. Han, T.C. Huang, Z.F. Huang, R.K. Li, W.Q. Li, C.-K. Loong, C.-X. Tang, Y. Tian, X.W. Wang, X.F. Xie, Q.Z. Xing, Z.F. Xiong, D. Xu, Y.G. Yang, Z. Zeng, H.Y. Zhang, X.Z. Zhang, S.X. Zheng, Z.H. Zheng, B. Zhong
  TUB, Beijing
• J.H. Billen, L.M. Young
  LANL, Los Alamos, New Mexico
• S. Fu, J. Tao, Y.L. Zhao
  IHEP Beijing, Beijing
• W.Q. Guan, Y. He, G.H. Li, J. Li, D.-S. zhang
  NUCTECH, Beijing
• J.H. Li
  CIAE, Beijing
• T.J. Liang
  Institute of Physics, Chinese Academy of Sciences, Beijing
• Z.W. Liu, L.T. Sun, H.W. Zhao
  IMP, Lanzhou
• B.B. Shao
  Tsinghua University, Beijing
• J. Stovall
  CERN, Geneva

This paper reports the design and construction status, technical challenges, and future perspectives of the proton-linac based Compact Pulsed Hadron Source (CPHS) at the Tsinghua University, Beijing, China.

• S.X. Zheng, X. Guan, J. Wei, H.Y. Zhang
  TUB, Beijing
• J.H. Billen, L.M. Young
  TechSource, Santa Fe, New Mexico
• J. Li, D.-S. zhang
  NUCTECH, Beijing
• J.H. Li
  CIAE, Beijing
• J. Stovall
  CERN, Geneva
• Y.L. Zhao
  IHEP Beijing, Beijing

The Compact Pulsed Hadron Source (CPHS) has launched at Tsinghua University to develop a university neutron source based on a 13 MeV, 50 mA proton linac which consists of ECR ion source, LEBT, RFQ and DTL. The primary design of the DTL for the CPHS is presented in this paper, which includes the dynamics calculation, RF field optimization and error analysis. This DTL can accelerate 50 mA proton beam from 3MeV to 13 MeV with 1.2 MW RF power input. The DTL is directly connected after RFQ without Medium-Energy Beam-Transport line (MEBT). PMQs are adopted in drift tubes focusing. The magnetic field gradient of PMQs are programmed to match the transverse restoring forces at the end of the RFQ to avoid missmatch and avoid parametric resonances.

• P.-CH. Yu, J. Wei
  TUB, Beijing
• Z.Q. He
  Tsinghua University, Beijing
• H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• A. Sessler
  LBNL, Berkeley, California
• Y. Yuri
  JAEA/TARRI, Gunma-ken

During the beam crystallization process, the main heating source is Intra-beam scattering (IBS), in which the Coulomb collisions among particles lead to a growth in the 6D phase space volume of the beam. The results of molecular dynamics (MD) simulation have shown an increase of heating rate as the temperature is increased from absolute zero, but then a peak in the heating rate, and subsequent decrease with ever increasing temperature*. This phenomenon has been carefully studied by Y. Yuri, H. Okamoto, and H. Sugimoto**. On the other hand, in the traditional IBS theory valid at high temperatures, heating rate is monotonically increasing as the temperature becomes lower***. In this paper we attempt to understand the "matching" at low temperatures between the MD results and traditional IBS theory, by including many body effects in the traditional IBS theory. In particular the Debye shielding is included. We shall present how the traditional theory is modified by shielding, and show how this effect improves the "matching" with the results from MD.

* J. Wei, H. Okamoto, and A. Sessler, Phys. Rev. Lett. 80, 2606
** Y.Yuri, H. Okamoto, and H. Sugimoto, J. Phys. Soc. Jpn. 78, 124501
***A. Piwinski, Lect. Notes Phys. 296, 297 (1988)

• Q.Z. Xing, Y.J. Bai, J.C. Cai, C. Cheng, T. Du, X. Guan, J. Wei, Z.F. Xiong, H.Y. Zhang, S.X. Zheng
  TUB, Beijing
• J.H. Billen, J. Stovall, L.M. Young
  TechSource, Santa Fe, New Mexico
• W.Q. Guan, Y. He, J. Li
  NUCTECH, Beijing

The design progress of the Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University is presented in this paper. The RFQ will accelerate protons from 50 keV to 3 MeV, with the RF frequency of 325 MHz. The objective is to obtain the optimum structure of the RFQ accelerator with high transmission rate and tolerable total length. The beam dynamics are studied by the simulation of the proton beam in the RFQ accelerator with the code of PARMTEQM. The output proton beam from the RFQ is well matched into the DTL without Medium-Energy-Beam-Transport (MEBT) between the RFQ and DTL.

* K.R. Crandall et al., RFQ Design Codes, LA-UR-96-1836.

• J. Wei
  TUB, Beijing

Since being introduced to accelerator physics, I have had the privilege to study and work with some of the best physicists on some of the most exciting projects. My first assignment was to simulate transition-crossing in RHIC in which a shocking 86% beam loss led to a redesign of its RF system which later earned me a Ph.D. Participation in the design, R&D, construction, and the commissioning of RHIC, not only was I introduced to the fascinating world of accelerator physics but was also trained as a physicist for accelerator projects. Since then, I have had the opportunity to work and lead teams of physicists and engineers on accelerator projects: US-LHC/AP at BNL, SNS/AP at ORNL, SNS ring, CSNS in China, and now CPHS at Tsinghua. The accelerator profession is uniquely rewarding in that ideas and dreams can be turned into reality through engineering projects, through which one experiences endless learning in physics, technology, teamwork and friendship. An example of enjoying the fun and friendship is the work on crystalline beams as a hobby for the past 18 years.

*Wei, Li, Sessler, Okamoto PRL73(94)3089; 80(98)2606
*Wei, Harrison XVI RCNP Osaka(97)
*Wei et al PAC99 2921
*Wei et al PAC01(01)319
*Wei RMP75(03)1383
*Wei et al NIMA600(09)10
*Wei et al PAC09

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