2011 Particle Accelerator Conference - List of Authors (Yeddulla, M.)

Paper

Title

Page

The Low-level Radio Frequency System for the Superconducting Cavities of National Synchrotron Light Source II

669

H. Ma, J. Cupolo, B. Holub, J. Oliva, J. Rose, R. Sikora, M. Yeddulla
BNL, Upton, Long Island, New York, USA

Funding: US DOE
A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19”/1-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.

TUP062

Design of Coupler for the NSLS-II Storage Ring Superconducting RF Cavity

931

M. Yeddulla, J. Rose
BNL, Upton, Long Island, New York, USA

NSLS-II requires four superconducting cavities working at 499.68 MHz. These cavities should support a 500 mA beam current. To operate the cavities in over-damped coupling condition, an External Quality Factor (Qext) of ~ 65000 is required. We have modified the existing coupler for the CESR-B cavity which has a Qext of ~ 200,000 to meet the requirements of NSLS-II. CESR-B cavity has an aperture coupler with a coupler "tongue" connecting the cavity to the waveguide. We have optimized the length, width and thickness of the "tongue" as well as the width of the aperture to increase the coupling using the three dimensional electromagnetic field solver, HFSS. Several possible designs will be presented.

WEP178

Electromagnetic Field Measurement of Fundamental and Higher-order Modes for 7-cell Cavity of PETRA-II

1822

Y. Kawashima, A. Blednykh, J. Cupolo, M.A. Davidsaver, B. Holub, H. Ma, J. Oliva, J. Rose, R. Sikora, M. Yeddulla
BNL, Upton, Long Island, New York, USA

The booster synchrotron for NSLS-II will include a 7-cell PETRA cavity, which was manufactured for the PETRA-II project at DESY. The cavity fundamental frequency operates at 500 MHz. In order to verify the impedances of the fundamental and higher-order modes (HOM) which were calculated by computer code, we measured the magnitude of the electromagnetic field of the fundamental acceleration mode and HOM’s, using the bead-pull method. To keep the cavity body temperature constant, we used a chiller system to supply cooling water at 20 degrees C. The bead-pull measurement was automated with a computer. We encountered some issues during the measurement process due to the difficulty in measuring the electromagnetic field magnitude in a multi-cell cavity as compared to a single-cell cavity. We describe the apparatus for the field measurement and the obtained results.

FROBS4

NSLS-II RF Systems

2583

J. Rose, W.K. Gash, B. Holub, Y. Kawashima, H. Ma, N.A. Towne, M. Yeddulla
BNL, Upton, Long Island, New York, USA

The NSLS-II RF systems include solid state modulators for the S-band klystrons powering the traveling wave sections for the 200 MeV injector linac, 7 cell cavity with IOT amplifier for the 3 GeV booster synchrotron and superconducting 500 MHz cavities powered by klystrons and a passive 1500 MHz SRF cavity for the 3 GeV, 500 mA storage ring. The systems are controlled by digital I/Q modulators fed by an ultra-low noise master oscillator. System overviews will be given along with preliminary test data.

Slides FROBS4 [1.041 MB]

Paper	Title	Page
MOP295	The Low-level Radio Frequency System for the Superconducting Cavities of National Synchrotron Light Source II	669
	H. Ma, J. Cupolo, B. Holub, J. Oliva, J. Rose, R. Sikora, M. Yeddulla BNL, Upton, Long Island, New York, USA
	Funding: US DOE A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19”/1-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.

TUP062	Design of Coupler for the NSLS-II Storage Ring Superconducting RF Cavity	931
	M. Yeddulla, J. Rose BNL, Upton, Long Island, New York, USA
	NSLS-II requires four superconducting cavities working at 499.68 MHz. These cavities should support a 500 mA beam current. To operate the cavities in over-damped coupling condition, an External Quality Factor (Qext) of ~ 65000 is required. We have modified the existing coupler for the CESR-B cavity which has a Qext of ~ 200,000 to meet the requirements of NSLS-II. CESR-B cavity has an aperture coupler with a coupler "tongue" connecting the cavity to the waveguide. We have optimized the length, width and thickness of the "tongue" as well as the width of the aperture to increase the coupling using the three dimensional electromagnetic field solver, HFSS. Several possible designs will be presented.

WEP178	Electromagnetic Field Measurement of Fundamental and Higher-order Modes for 7-cell Cavity of PETRA-II	1822
	Y. Kawashima, A. Blednykh, J. Cupolo, M.A. Davidsaver, B. Holub, H. Ma, J. Oliva, J. Rose, R. Sikora, M. Yeddulla BNL, Upton, Long Island, New York, USA
	The booster synchrotron for NSLS-II will include a 7-cell PETRA cavity, which was manufactured for the PETRA-II project at DESY. The cavity fundamental frequency operates at 500 MHz. In order to verify the impedances of the fundamental and higher-order modes (HOM) which were calculated by computer code, we measured the magnitude of the electromagnetic field of the fundamental acceleration mode and HOM’s, using the bead-pull method. To keep the cavity body temperature constant, we used a chiller system to supply cooling water at 20 degrees C. The bead-pull measurement was automated with a computer. We encountered some issues during the measurement process due to the difficulty in measuring the electromagnetic field magnitude in a multi-cell cavity as compared to a single-cell cavity. We describe the apparatus for the field measurement and the obtained results.

FROBS4	NSLS-II RF Systems	2583
	J. Rose, W.K. Gash, B. Holub, Y. Kawashima, H. Ma, N.A. Towne, M. Yeddulla BNL, Upton, Long Island, New York, USA
	The NSLS-II RF systems include solid state modulators for the S-band klystrons powering the traveling wave sections for the 200 MeV injector linac, 7 cell cavity with IOT amplifier for the 3 GeV booster synchrotron and superconducting 500 MHz cavities powered by klystrons and a passive 1500 MHz SRF cavity for the 3 GeV, 500 mA storage ring. The systems are controlled by digital I/Q modulators fed by an ultra-low noise master oscillator. System overviews will be given along with preliminary test data.
	Slides FROBS4 [1.041 MB]