Author: Geng, R.L.
Paper Title Page
WEPPC049 Individual RF Test Results of the Cavities Used in the First US-built ILC-type Cryomodule 2321
  • A. Hocker, A.C. Crawford, E.R. Harms, A. Lunin, D.A. Sergatskov, A.I. Sukhanov
    Fermilab, Batavia, USA
  • G.V. Eremeev, R.L. Geng
    JLAB, Newport News, Virginia, USA
  • J.P. Ozelis
    FRIB, East Lansing, USA
  Funding: Work supported in part by the U.S. Department of Energy under Contract No. DE-AC02-07CH11359.
Eight 1.3-GHz, nine-cell SRF cavities have been installed in a cryomodule intended to demonstrate the ILC design goal of 31.5 MV/m. These cavities all underwent two types of individual RF testing: a low-power continuous-wave test of the “bare” cavity and a high-power pulsed test of the “dressed” cavity. Presented here is a discussion of the results from these tests and a comparison of their performance in the two configurations.
WEPPC094 Optimizing Centrifugal Barrel Polishing for Mirror Finish SRFCavity and Rf Tests at Jefferson Lab 2435
  • A.D. Palczewski, R.L. Geng, H. Tian
    JLAB, Newport News, Virginia, USA
  Funding: This work is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We performed Centrifugal Barrel Polishing (CBP) on a 1.3GHz fine grain ILC SRF cavity following a modified version of the recipe* originally developed at Fermilab (FNAL)**. We were able to obtain a mirror like surface similar to that obtained at FNAL, while reducing the number of CBP steps. This paper will discuss the change in surface and subsequent cavity performance before CBP on a raw cavity and post CBP, after a 800C bake (no pre-bake chemistry) and minimal controlled electro-polishing (below 10 micron). In addition to Q vs. Eacc thermometry maps with preheating characteristics and optical inspection of the cavity before and after CBP will also be shown.
* A. D. Palczewski et al., Proc. of SRF2011, THPO071 (2011).
** C.A. Cooper et al., FERMILAB-PUB-11-032-TD, (May 31, 2011).
WEPPC095 Evaluation of Silicon Diodes as In-situ Cryogenic Field Emission Detectors for SRF Cavity Development 2438
  • A.D. Palczewski, R.L. Geng
    JLAB, Newport News, Virginia, USA
  Funding: This work is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We performed in-situ cryogenic testing of five silicon diodes as possible candidates for field emission monitor of SRF cavities in vertical testing dewars and in cryo-modules. We evaluated diodes from 2 companies - from Hamamatsu corporation model S5821-02 (used at KEK)* and S1223-02; and from OSI Optoelectronics models OSD35-LR-A, XUV-50C, and FIL-UV20. The measurements were done by placing the diodes in superfluid liquid helium near a field emitting 9-cell cavity during its vertical test. For each diode, we will discuss their viability as a 2K cryogenic detector for FE mapping of SRF cavities and their directionality in such environments. We will also present calibration curves between the diodes and JLab’s standard radiation detector placed above the dewar top plate and within radiation shielding.
* H. Sakai et al., Proc of IPAC10, WEPEC028 p. 2950 (2010).
WEPPC038 Status of the Short-Pulse X-ray Project at the Advanced Photon Source 2292
  • A. Nassiri, N.D. Arnold, T.G. Berenc, M. Borland, B. Brajuskovic, D.J. Bromberek, J. Carwardine, G. Decker, L. Emery, J.D. Fuerst, A.E. Grelick, D. Horan, J. Kaluzny, F. Lenkszus, R.M. Lill, J. Liu, H. Ma, V. Sajaev, T.L. Smith, B.K. Stillwell, G.J. Waldschmidt, G. Wu, B.X. Yang, Y. Yang, A. Zholents
    ANL, Argonne, USA
  • J.M. Byrd, L.R. Doolittle, G. Huang
    LBNL, Berkeley, California, USA
  • G. Cheng, G. Ciovati, P. Dhakal, G.V. Eremeev, J.J. Feingold, R.L. Geng, J. Henry, P. Kneisel, K. Macha, J.D. Mammosser, J. Matalevich, A.D. Palczewski, R.A. Rimmer, H. Wang, K.M. Wilson, M. Wiseman
    JLAB, Newport News, Virginia, USA
  • Z. Li, L. Xiao
    SLAC, Menlo Park, California, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source Upgrade (APS-U) Project at Argonne will include generation of short-pulse x-rays based on Zholents’* deflecting cavity scheme. We have chosen superconducting (SC) cavities in order to have a continuous train of crabbed bunches and flexibility of operating modes. In collaboration with Jefferson Laboratory, we are prototyping and testing a number of single-cell deflecting cavities and associated auxiliary systems with promising initial results. In collaboration with Lawrence Berkeley National Laboratory, we are working to develop state-of-the-art timing, synchronization, and differential rf phase stability systems that are required for SPX. Collaboration with Advanced Computations Department at Stanford Linear Accelerator Center is looking into simulations of complex, multi-cavity geometries with lower- and higher-order modes waveguide dampers using ACE3P. This contribution provides the current R&D status of the SPX project.
* A. Zholents et al., NIM A 425, 385 (1999).