Author: Li, Z.
Paper Title Page
TUPWA013 Study of the C-ADS Longitudinal Beam Instabilities Caused by HOMS 1751
  • P. Cheng, Z. Li, J.Y. Tang, J.Q. Wang
    IHEP, Beijing, People's Republic of China
  The C-ADS accelerator is a CW proton linac which accelerates the beam to 1.5GeV. It has the characteristics of being very high beam power and very high reliability that are not posed by any of the existing proton linacs. The accelerator uses two families (β=0.63 and β=0.82 ) of elliptical five cell superconducting cavities. High Order Modes can severely limit the operation of these cavities. Monopole modes are found by Microwave Studio CST. Then the longitudinal instability caused by these monopole modes are primarily investigated with code bbusim, taking into account of effects like High Order Modes frequency spread, beam input jitters and other beam and RF parameters of the beams and cavities. Preliminary simulation results show that monopole modes induced instability is not a problem if High Order Modes frequency spread is not less than 1MHz. However, further investigations are necessary in order to make a critical decision such as whether HOM damper will be adopted. Study on the transverse case is under way.  
TUPWA018 Local Compensation-Rematch for Element Failures in the Low Energy Section of C-Ads Accelerator 1760
  • B. Sun, Z. Li, J.Y. Tang, F. Yan
    IHEP, Beijing, People's Republic of China
  Due to the requirement of high reliability and availability for the C-ADS accelerators, a fault tolerance design is pursued. The effects of transverse focusing element failures in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one transverse element failure especially in the low energy section happens, some new methods have been purposed by which the new settings of the neighbouring solenoids and the cavities can be set, and the Twiss parameters and energy can be approximately recovered to that of the nominal ones at the matching point. We find that the normalized RMS emittance in transverse and longitudinal planes have no obvious growth after applying the compensation in each section of the main linac. When we make study on the compensation-rematch for the RF cavity failures, the TraceWin code has been used that doesn’t consider the phase change during the cavity resetting, so a code named LOCCOM, which is based on MATLAB, is developed and used to compensate the error on arrival-time at the matching point.  
TUPWA020 The Implementation of Equipartitioning in the Proton Linac Code PADSC 1766
  • Y.L. Zhao, S. Fu, Z. Li
    IHEP, Beijing, People's Republic of China
  The high intensity accelerator projects place extremely stringent requirements on particle loss, since even very small losses can lead to unacceptably high levels of radioactivity that can hinder or prevent hands-on maintenance. Such losses are known to be associated with emittance growth and beam halo. Non-equipartitioning contributes a lot for emittance growth and beam halo. The present equipartitioning realization has assumed that the emittance and space charge force are keeping constant, which will induce errors. The implementation in the proton linac code PADSC does equipartitioning optimization according to the real space charge force and emittance in the quasi period lattice.  
TUPWO019 A Local Achromatic Design of C-ADS MEBT2 1922
  • H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  The accelerator of China Accelerator Driven Sub-critical system consists of two injectors to ensure its high reliability. The Medium Energy Beam Transport line-2 is an essential part of the accelerator to transport and match the beam from either injector to the main linac. This paper presents a local achromatic design, which uses four bending magnets, for CADS MEBT2. It is found that both transverse and longitudinal emittance growths can be well controlled below 15% from MEBT2 entrance to the exit of the following superconducting spoke-021 section. The beam dynamics of MEBT2 will be discussed and the multi-particle tracking results will also be shown.  
TUPWO020 Error Analysis for C-ADS MEBT2 1925
  • H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  A local achromatic scheme has been developed for C-ADS MEBT2. This paper presents the error analysis results for this MEBT2 scheme. The effects of magnet and cavity misalignment, static and dynamic errors of electric and magnetic field, the displacement of the input beam as well as the initial mismatches of the incoming beam will be studied. Beam trajectory correction scheme will also be discussed.  
THPWO040 Progress of Injector-1 and Main Linac of Chinese ADS Proton Accelerator 3854
  • Y.L. Chi, J. Cao, J.P. Dai, H. Dong, L. Dong, T.M. Huang, X. Jing, S.P. Li, Z. Li, Z.Q. Li, Z.C. Liu, F. Long, Z. Ma, H.F. Ouyang, W.M. Pan, Q.L. Peng, P. Su, Y.F. Sui, J.Y. Tang, J.L. Wang, Q.B. Wang, Q. Ye, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
  China ADS study program was Supported by the "Strategic Priority Research Program " of the Chinese Academy of Sciences at 2011, which aims to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power in about twenty years. The driver Linac is defined to be1.5 GeV in energy, 10mA in current and in CW operation mode. To meet the extremely high reliability and availability of ADS, the Linac is designed with much installed margin and fault tolerance. ADS accelerator is composed of two parallel 10MeV injectors and a main Linac. The superconducting acceleration structures are employed except the RFQs. This paper will present design of the China ADS accelerator and related key technology developments.  
THPWO043 Progress on the Physics Design of the C-ADS Injector Scheme I 3863
  • Z. Li, P. Cheng, H. Geng, C. Meng, H.F. Ouyang, B. Sun, J.Y. Tang, F. Yan, Z. Yang
    IHEP, Beijing, People's Republic of China
  Funding: Surported by China ADS Project
The China ADS (C-ADS) driver linac is composed of two parallel 10 MeV injectors and a main linac which boosts the beam further to 1.5 MeV. There are two design schemes for the injectors based on different working frequency and superconducting cavity structures and are under developing at the same time on IHEP and IMP. The Injector Scheme I, which is proposed by IHEP, works at 325 MHz, the same frequency of the main linac, and superconducting Spoke cavities with geometry beta of 0.12, the same type of cavity as the main linac too, are applied after the RFQ. In this paper, the latest progress on physics design will be presented.
THPWO044 Error Analysis and Beam Loss Control in C-ADS Main Linac 3866
  • C. Meng, Z. Li, J.Y. Tang, F. Yan
    IHEP, Beijing, People's Republic of China
  The China ADS (C-ADS) driver linac is defined to deliver a CW proton beam of 1.5 GeV in energy and 10 mA in current. To meet the extremely high reliability and availability, it is very important and imperative to perform detailed error analysis to simulate the real machine, where the errors always exist. The error studies are by very intense macro-particle simulations by both Trace-Win and TRACK codes with space charge effects included. Through error analysis the proper closed-orbit correction scheme and the maximum tolerable hardware and alignment errors can be found. This paper presents the method to optimize the apertures of elements in the C-ADS main linac. According to the detailed sensitivity analysis of different errors, the static and dynamic errors for the main linac are proposed. The basic lattice scheme has also been re-optimized based on the error studies. The correction scheme is also described, and with the correction scheme the residual orbit can be controlled very well. The influence of the correctors and BPM failures on the correction scheme is also studied.