Author: Sun, Y.
Paper Title Page
MOEPPB004 A Compact Ring Design with Tunable Momentum Compaction 82
 
  • Y. Sun
    SLAC, Menlo Park, California, USA
  
  A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and pre- damping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.  
 
MOOAB03 FACET First Beam Commissioning 46
 
  • G. Yocky, C.I. Clarke, W.S. Colocho, F.-J. Decker, M.J. Hogan, N. Lipkowitz, J. Nelson, P.M. Schuh, J.T. Seeman, J. Sheppard, H. Smith, T.J. Smith, M. Stanek, Y. Sun, J.L. Turner, M.-H. Wang, S.P. Weathersby, G.R. White, U. Wienands, M. Woodley
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The FACET (Facility for Advanced aCcelerator Experimental Tests) facility at SLAC has been under Construction since summer 2010. Its goal is to produce ultrashort and transversely small bunches of very high intensity (20kA peak current) to facilitate advanced acceleration experiments like PWFA and DLA. In June of 2011 the first electron beam was brought into the newly constructed bunch-compression chicane. Commissioning work included restarting the linac and damping ring, verifying hardware, establishing a good beam trajectory, verifying the optics of the chicane, commissioning diagnostic devices for transverse and longitudinal bunch size, and tuning up the beam size and bunch compression. Running a high-intensity beam through the linac without BNS damping and with large energy spread is a significant challenge. Optical aberrations as well as wakefields conspire to increase beam emittance and the bunch compression is quite sensitive to details of the beam energy and orbit, not unlike what will be encountered in a linear-collider final-focusing system. In this paper we outline the steps we took while commissioning as well as the challenges encountered and how they were overcome. 		 
slides icon Slides MOOAB03 [9.167 MB]  
 
WEPPD068 High Power Collinear Load Coated with FeSiAl 2678
 
  • L.G. Shen, X.L. Fu, Y. Sun, F. Zhang
    USTC/PMPI, Hefei, Anhui, People's Republic of China
  • Y.J. Pei
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: This work is supported by the NSFC (NO. 10775128 and NO.51075381)
Aimed at substituting output coupler to absorb remnant power of the LINAC, collinear load coated with high loss materials is expected to come reality. FeSiAl load is studied. The effect of the coating volume upon the cavity frequency and Q factor is analyzed and the dimension compensations of the cavities are suggested to tune the load cavities at 2856 MHz. Orthogonal Experimental Method is utilized to investigate the sensitivity of permittivity (both real part and imaginary part) and permeability (both real part and imaginary part) to cavity characteristics. Five cavities with different coating dimensions are manufactured and their operating frequencies and Q are measured. Compared with the simulations, they show that the Q factor, which is characterization of the actual attenuation of the FeSiAl, agrees very well with the theoretical value and Q factor of the resonant cavity is measured with the probe method. The relationship between Q factor and the length of the test probe is deduced and eventually the individual Q value of a load cavity is extracted. Simulation shows the FeSiAl load can support average power over 15 kW and the one-way attenuation is about 30 dB.