Author: He, F.S.
Paper Title Page
MOP019
 Comparison of Linacs for Small-Scale Inverse Compton Scattering Light Source Applications  
 
  • F.S. He, F.E. Hannon, J.D. Mammosser, R.A. Rimmer, H. Wang
    JLAB, Newport News, Virginia, USA
  
  Funding: Work supported by DOE
Great interest has been generated by the possibility of compact, high brilliance X-ray source based on inverse Compton scattering (ICS) since the rapid advancement in laser and accelerator technologies. While most superconducting (SC) linac designs have been aimed at large high energy facilities throughout the world, a compact and affordable SC linac that fits compact ICS source would be very attractive. MIT had proposed such concept, but the linac for electron acceleration after injector was not well defined then. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS applications. The linac is designed to accelerate an electron beam with a bunch charge of 5 pC at 200 MHz repetition rate, increasing the energy by 17 MeV. SC elliptical cavities at various frequencies, SC spoke cavity with β=1, and normal conducting (NC) cavities were compared in order to minimize the dynamic heat load. In this paper, the performance, capital and operational cost are compared among different options, and the choice of JLab is justified. 		 
slides icon Slides MOP019 [0.846 MB]  
 
THP013 A New Cavity Design for Medium Beta Acceleration 920
 
  • F.S. He, R.A. Rimmer, H. Wang
    JLAB, Newport News, Virginia, USA
  
  Funding: Work supported by DOE
Heavy duty or CW, superconducting proton and heavy ion accelerators are being proposed and constructed worldwide. The total length of the machine is one of the main drivers in terms of cost. Thus HWR and spoke cavities at medium beta are usually optimized to achieve low surface field and high gradient. A novel accelerating structure at β=0.5 evolved from spoke cavity is proposed, with lower surface fields but slightly higher heat load. It would be an interesting option for pulsed and CW accelerators with beam energy of more than 200MeV/u. 		 
 
THP014
 A Prototype Cavity for Inverse Compton Scattering Light Source Applications  
 
  • F.S. He, G. Cheng, W.A. Clemens, J. Henry, P. Kneisel, B.R. Lang, J.D. Mammosser, R.A. Rimmer, G. Slack, C. Tennant, L. Turlington, H. Wang, S. Yang
    JLAB, Newport News, Virginia, USA
  
  Funding: Work supported by DOE
Compact, high brilliance X-ray sources, based on inverse Compton scattering (ICS), have gained enormous interest worldwide. A compact and affordable superconducting (SC) linac is one of the key components of such applications. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS application. In this paper, the RF optimization, HOM criteria, mechanical analysis, fabrication experience and the test result of the prototype cavity are reported. 		 
slides icon Slides THP014 [2.718 MB]  
 
TUP033 Magnetic Property Improvement of Niobium Doped with Rare Earth Elements 490
 
  • F.S. He, F. He, F. Jiao, X.Y. Lu, K. Zhao
    PKU, Beijing, People's Republic of China
  • L. Chen
    NNIEC, Shizuishan City, Ningxia, People's Republic of China
  • T.C. Jiang
    IMP, Lanzhou, People's Republic of China
  • Y. You, H.Y. Zhao
    Ningxia Orient Tantalum Industry Co., Ltd., Dawukou District, Shizuishan city, People's Republic of China
  
  A new idea of modifying the raw niobium was proposed by PKU in 2010, by introducing rare earth elements of Sc and Y into Nb ingot during smelting process. Test results on small samples were very promising*: the Tc was same as Nb, while the Hc1 and Hc2 were increased by 500-700 Oe and up to 4000 Oe, respectively. Recently one Nb ingot doped with Sc was successfully smelted under the collaboration of PKU and OSTEC at Ningxia, and two TESLA-type half cells were fabricated out of the new material by deep drawing. The Hc1 measured from the drop-off of the blanks were consistently high. The RRR was 127, while the mechanical properties met the ILC requirement. One single cell cavity is being fabricated, and vertical test is planned to study the SRF properties of the new material. There is a good chance that the quenching could be pushed to a higher gradient. Another innovative idea of doping only the surface layer of bulk Nb by ion implantation in the pelletron at PKU is also being investigated, in order to improve the SRF performance of the surface layer while maintaining the high thermal conductivity of bulk Nb. Some initial testing results of the new method will be reported as well.
* TTC2012 at JLab:
https://www.jlab.org/indico/getFile.py/access?contribId=78&sessionId=8&resId=0&materialId=slides&confId=24