Author: Valles, N.R.A.
Paper Title Page
WEEPPB015 Temperature Dependence of the Superheating Field: DC and RF Critical Fields 2197
  • N.R.A. Valles, M. Liepe
    CLASSE, Ithaca, New York, USA
  The superheating field is a metastable state at which the Meissner state persists at fields higher than would be predicted from steady-state energy considerations. Previous work demonstrated that a phenomenological approach based on the RF superheating field scaling near the critical temperature is also consistent with low temperature results. This work expands upon the RF results by measuring the DC superheating field, and comparing it to RF results and theoretical predictions.  
WEPPC070 Automated Cavity Test Suite for Cornell's ERL Program 2372
  • D. Gonnella, M. Liepe, N.R.A. Valles
    CLASSE, Ithaca, New York, USA
  As of 2011, fabrication and testing of main linac 7-cell cavities has begun for Cornell's Energy Recovery Linac prototype project. To standardize the testing process, minimize errors and allow for quick and precise measurements of these cavities, a suite of MatLab programs has been written to automate cavity tests. The programs allow measuring the quality factor versus temperature, and quality factor vs. accelerating gradient, and allow extracting material properties such as RRR and residual resistance. They are compatible with EPICS input/output controllers or standalone computers. Finally, the program can measure continuous Q vs E curves from a single high field decay curve, and can perform temperature mapping and quench localization from oscillating superleak transducer data.  
WEPPC073 Progress on Superconducting RF Work for the Cornell ERL 2381
  • M. Liepe, F. Furuta, G.M. Ge, Y. He, G.H. Hoffstaetter, T.I. O'Connell, S. Posen, J. Sears, M. Tigner, N.R.A. Valles, V. Veshcherevich
    CLASSE, Ithaca, New York, USA
  Cornell University is developing the superconducting RF technology required for the construction of a 100 mA hard X-ray light source driven by an Energy-Recovery Linac. Prototypes of all beam line components of the 5 GeV cw SRF main linac cryomodule have been fabricated and tested in detail. This work includes an optimized 7-cell SRF cavity, a broadband HOM beamline absorber, a cold frequency tuner, and a 5 kW CW RF input coupler. A one-cavity test cryomodule has been assembled for a first full cryomodule test of the main linac cavity, and is currently under testing. In this paper we give an overview of these extensive R&D activities at Cornell.  
WEPPC074 HOM Studies on the Cornell ERL Prototype Cavity in a Horizontal Test Cryomodule 2384
  • N.R.A. Valles, M.G. Billing, G.H. Hoffstaetter, M. Liepe, C.E. Mayes
    CLASSE, Ithaca, New York, USA
  The main linac 7-cell cavity for Cornell's Energy Recovery Linac was optimized to maximize threshold current through the ERL. This was achieved by designing center and end cells that reduce the strength of dipole higher-order modes. A prototype cavity was fabricated based on the optimized RF design and found to meet fundamental mode specifications in a vertical test. The higher-order-mode spectrum was measured when the cavity was installed in a horizontal test cryomodule and is compared to 2D and 3D EM simulations.  
WEPPC075 Testing of the Main-Linac Prototype Cavity in a Horizontal Test Cryomodule for the Cornell ERL 2387
  • N.R.A. Valles, F. Furuta, G.M. Ge, Y. He, K.M.V. Ho, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, S. Posen, P. Quigley, J. Sears, M. Tigner, V. Veshcherevich
    CLASSE, Ithaca, New York, USA
  Cornell has recently finished producing and testing the first prototype 7-cell main linac cavity for the Cornell Energy Recovery Linac (ERL). The cavity construction met all necessary fabrication constraints. After a bulk BCP, 650C outgassing, final BCP, and 120C bake the cavity was vertically tested. The cavity met quality factor and gradient specifications (2·1010 at 16.2 MV/m) in the vertical test. Progressing with the ERL linac development, the cavity was installed in a horizontal test cryomodule and the quality factor versus accelerating gradient was again measured. This baseline measurement is the first test in a sequence of tests of the main linac cavity in the test cryomodule. Subsequent tests will be with increased complexity of the beam line, e.g. with HOM beamline loads installed, to study potential sources of reducing the cavity’s quality factor.