PAC2013 - List of Authors (Ghosh, A.K.)

Paper	Title	Page
THPBA07	Superconducting Corrector IR Magnet Production for SuperKEKB	1241
	B. Parker, M. Anerella, J. Escallier, A.K. Ghosh, H.M. Hocker, A.K. Jain, A. Marone, P. Wanderer BNL, Upton, Long Island, New York, USA Y. Arimoto, M. Iwasaki, N. Ohuchi, M. Tawada, K. Tsuchiya, H. Yamaoka, Z.G. Zong KEK, Ibaraki, Japan
	The SuperKEKB luminosity upgrade IR needs 43 different superconducting correction coils. There are dipole (b1), skew-dipole and skew-quad correctors, (a1, a2), for orbit and optics control and b3 and b4 correctors for acceptable circulating beam lifetime. Most coils are sandwiched inside the main IR quad apertures but a few are located on independent support tubes outside the quad collars or on interconnects between quads. Four complex external field cancel coils, b3-b6, are needed to buck non-linear fields outside the quads closest to the interaction point. In the IR crossing angle geometry the first quads have no magnetic yokes and the cancel coils’ end turn spacings must match the field falloff with increasing beam separation. SuperKEKB IR correctors have tight harmonic tolerances with allowed field deviation at the reference radius of a few gauss at each position along the coil. Also the cancel coils have a position dependent “twist” to generate the correct local amount of skew field for the SuperKEKB optics.

THPHO09	High Intensity RHIC Limitations Due to Signal Heating of the Cryogenic BPM Cables	1319
	P. Thieberger, J.A. D'Ambra, A.K. Ghosh, K. Hamdi, K. Mernick, T.A. Miller, M.G. Minty, C. Pai BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The signal cables from the beam position monitors (BPMs) in the cryogenic sections of RHIC need to satisfy somewhat conflicting requirements. On the one hand, the cryogenic load due to heat conduction along the cable needs to be small, which led to the use of stainless steel jacketed cables with Tefzel insulation. On the other hand, radio frequency losses need to be reasonably small to reduce heating due to dissipated signal power. As the beam intensity in RHIC increased over the years, and the bunches become shorter, a point is being rapidly approached where these cables will soon become a performance limiting factor. Here we describe an extensive study of this problem including cable loss measurements as a function of temperature and frequency, characterization of the copper center conductor, and Particle Studio and ANSYS simulations.

Paper

Title

Page

Superconducting Corrector IR Magnet Production for SuperKEKB

1241

B. Parker, M. Anerella, J. Escallier, A.K. Ghosh, H.M. Hocker, A.K. Jain, A. Marone, P. Wanderer
BNL, Upton, Long Island, New York, USA
Y. Arimoto, M. Iwasaki, N. Ohuchi, M. Tawada, K. Tsuchiya, H. Yamaoka, Z.G. Zong
KEK, Ibaraki, Japan

The SuperKEKB luminosity upgrade IR needs 43 different superconducting correction coils. There are dipole (b1), skew-dipole and skew-quad correctors, (a1, a2), for orbit and optics control and b3 and b4 correctors for acceptable circulating beam lifetime. Most coils are sandwiched inside the main IR quad apertures but a few are located on independent support tubes outside the quad collars or on interconnects between quads. Four complex external field cancel coils, b3-b6, are needed to buck non-linear fields outside the quads closest to the interaction point. In the IR crossing angle geometry the first quads have no magnetic yokes and the cancel coils’ end turn spacings must match the field falloff with increasing beam separation. SuperKEKB IR correctors have tight harmonic tolerances with allowed field deviation at the reference radius of a few gauss at each position along the coil. Also the cancel coils have a position dependent “twist” to generate the correct local amount of skew field for the SuperKEKB optics.

THPHO09

High Intensity RHIC Limitations Due to Signal Heating of the Cryogenic BPM Cables

1319

P. Thieberger, J.A. D'Ambra, A.K. Ghosh, K. Hamdi, K. Mernick, T.A. Miller, M.G. Minty, C. Pai
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The signal cables from the beam position monitors (BPMs) in the cryogenic sections of RHIC need to satisfy somewhat conflicting requirements. On the one hand, the cryogenic load due to heat conduction along the cable needs to be small, which led to the use of stainless steel jacketed cables with Tefzel insulation. On the other hand, radio frequency losses need to be reasonably small to reduce heating due to dissipated signal power. As the beam intensity in RHIC increased over the years, and the bunches become shorter, a point is being rapidly approached where these cables will soon become a performance limiting factor. Here we describe an extensive study of this problem including cable loss measurements as a function of temperature and frequency, characterization of the copper center conductor, and Particle Studio and ANSYS simulations.