PAC09 - List of Authors (Naik, D.)

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Naik, D.

Paper	Title	Page
TU5PFP037	Ripple Structure in 56 MHz Quarter Wave Resonator for Multipacting Suppression	903
	I. Ben-Zvi, D. Naik BNL, Upton, Long Island, New York
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A beam excited 56 MHz RF Niobium Quarter Wave Resonator has been proposed to enhance RHIC beam luminosity and bunching. As multipacting is expected, an extensive study was carried out with the Multipac 2.1 code, looking for a way to suppress it. Multipacting bands were found. Discharge occurred at cavity’s top corner above beam gap and on outer conductor up to more than half its length, moving towards the end of the cavity. We find single-point multipacting, with emission from the outer conductor, as well as two-point multipacting involving both inner and outer conductor. We found a geometric approach to suppressing multipacting. The most promising method was ripples in outer conductor. Ripples’ depth, width and gap were optimized. In shallow depth of 1 cm, electrons multiply, drift further, however they are stopped by 2 cm ripples. Width of 1 and 3 cm didn’t work as in 1 cm electrons emerge out of it, whereas, in 3 cm, they resonate and trap inside. A 2 cm wide was found good. Likewise, 2 cm gap was valuable. Finally, we find that ripples of 2 cm deep, 2 cm wide spaced by 2 cm completely suppressed multipacting, and were adopted for fabrication.

Paper

Title

Page

TU5PFP037

Ripple Structure in 56 MHz Quarter Wave Resonator for Multipacting Suppression

903

I. Ben-Zvi, D. Naik
BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

A beam excited 56 MHz RF Niobium Quarter Wave Resonator has been proposed to enhance RHIC beam luminosity and bunching. As multipacting is expected, an extensive study was carried out with the Multipac 2.1 code, looking for a way to suppress it. Multipacting bands were found. Discharge occurred at cavity’s top corner above beam gap and on outer conductor up to more than half its length, moving towards the end of the cavity. We find single-point multipacting, with emission from the outer conductor, as well as two-point multipacting involving both inner and outer conductor. We found a geometric approach to suppressing multipacting. The most promising method was ripples in outer conductor. Ripples’ depth, width and gap were optimized. In shallow depth of 1 cm, electrons multiply, drift further, however they are stopped by 2 cm ripples. Width of 1 and 3 cm didn’t work as in 1 cm electrons emerge out of it, whereas, in 3 cm, they resonate and trap inside. A 2 cm wide was found good. Likewise, 2 cm gap was valuable. Finally, we find that ripples of 2 cm deep, 2 cm wide spaced by 2 cm completely suppressed multipacting, and were adopted for fabrication.