IPAC2012 - List of Authors (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.

Paper

Title

Page

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.