• S. Fu, S.X. Fang, J.Q. Wang
  IHEP Beijing, Beijing
• X. Guan
  CIAE, Beijing

In the next two decades, China will be in period of fast development of nuclear power to meet the energy demands of the rapid economy growth and to cut down the CO2 release. Accelerator Driven System is recognized as the best option for nuclear radioactive waste transmutation. ADS long-term development roadmap has been proposed. Based on the ADS basic study in the last decade, a samll-scale ADS facility is going to be built to do experimental research on ADS system. In this paper, we will first review the previous R&D activity on ADS linac research in China, and then introduce the design of the linac in the small-scale ADS facility.

• X. Guan
  TUB, Beijing

This paper will be generally reported that a new project of the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China. CPHS consists of a proton linac (13MeV, 16kW, Operating frequency 325MHz, peak current 50 mA, 0.5 ms pulse width at 50 Hz), a neutron target station (a Be target, moderators and reflector), and a small-angle neutron scattering instrument, a neutron imaging/radiology station, and a proton irradiation station. The linac accelerator is the main part of this project, which including a ECR ion source. LEBT section, a RFQ accelerator, a DTL linac and a HEBT An An experimental platform for further proton applications and more neutron beam lines will be added at a later stage. Currently, fabrication of the accelerator components has begun while the neutron target station, beam lines and instruments are under design study. The initial phase of the CPHS construction is scheduled to complete in the end of 2012.

• C. Cheng, T. Du, X. Guan, J. Wei, S.X. Zheng
  TUB, Beijing

The Compact Pulsed Hadron Source (CPHS) system has been proposed and designed by the Department of Engineering Physics of Tsinghua University in Beijing, China. It consists of an accelerator front-end'a high-intensity ion source, a 3 MeV radiofrequency quadrupole linac (RFQ), and a 13 MeV drift-tube linac (DTL), a neutron target station, and some experimental stations. In our design, both RFQ and DTL share a single klystron which is capable of 2.5 MW peak RF power and a 3.33% duty factor. The 325 MHz klystron contains a modulating anode and has a 100 kW average output power. Portions of the RF system, such as pulsed high voltage power source, modulator, crowbar protection and RF transmission system are all presented in details in this paper.

• Q.Z. Xing, Y.J. Bai, J.C. Cai, X. Guan, X.W. Wang, J. Wei, Z.F. Xiong, H.Y. Zhang
  TUB, Beijing
• J.H. Billen, L.M. Young
  LANL, Los Alamos, New Mexico
• W.Q. Guan, Y. He, J. Li
  NUCTECH, Beijing
• J. Stovall
  CERN, Geneva

We present, in this paper, the physics and mechanical design of a Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. The 3-meter-long RFQ will accelerate protons from 50 keV to 3 MeV at an RF frequency of 325 MHz. In the physics design we have programmed the inter-vane voltage as a function of beam velocity, to optimize the performance of the RFQ, by tailoring the cavity cross section and vane-tip geometry as a function of longitudinal position while limiting the peak surface electric field to 1.8 Kilpatrick. There will be no Medium-Energy-Beam-Transport (MEBT) following the RFQ. The focusing at the high energy end of the RFQ and at the entrance of the DTL have been tailored to provide continuous restoring forces independent of the beam current. In simulations of the proton beam in the RFQ, using the code PARMTEQM, we observe transmission exceeding 97%. The RFQ is mechanically separated into three sections to facilitate machining and brazing. We have machined a test section and the final RFQ accelerator is now under construction. We will describe the status of the RFQ system in this paper.

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

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

The CPHS project in Tsinghua University plans to construct a 13 MeV linear accelerator to deliver a pulsed proton beam having an average beam current of 2.5 mA. A Drift Tube Linac (DTL), following a Radio Frequency Quadrupole accelerator(RFQ), will accelerate protons from 3 to 13MeV. The accelerating field and phase will be ramped to match the longitudinal restoring forces at the end of the RFQ. Likewise, the transverse focusing forces, provided by permanent-magnet quadrupole lenses (PMQs) will be programmed to match the transverse restoring forces at the end of the RFQ to avoid missmatch and avoid parametric resonances. We will present the main physics design parameters of CPHS DTL and describe the properties of the resonant cavity. We plan to apply electron beam welding technology exclusively in the fabrication of the drift tubes and will present the test results from our engineering prototyping program.

• Z. Feng, X. Guan, J. Wei, H.Y. Zhang
  TUB, Beijing
• Z.W. Liu, H.W. Zhao
  IMP, Lanzhou

Responding to the demand of accelerator front inject system of the Compact Pulsed Hadron Source (CPHS) in Tsinghua university in 2009, an electron cyclotron resonance (ECR) proton source (2.45 GHz, 1.5 KW) and a low-energy-beam-transport (LEBT) system are designed and manufacted. In this source, the H2 plasma is restricted by an axial magnetic field shaped by the source body produced by an all-permanent-magnet design (NdFeB rings). The 50-keV pulsed proton beam (50 Hz/0.5 ms) extracted by a four-electrode extraction system from the proton source passes through the LEBT system (1283 mm long), which is consist of two solenoid lens, two steering magnets and a cone configuration optically matches to the RFQ where the Twiss parameters α=1.354, β=7.731. The beam with 97% space charge neutralization rate has been simulated at 100 mA, 150 mm.mrad RFQ output current by Trace-3D and PBGUN. In this study, we describe the design of the proton source and LEBT technical systems along with intended operation.