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Title: ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.

Abstract

Since 2081 MIC has experienced electron cloud effects, which have limited the beam intensity. These include dynamic pressure rises - including pressure instabilities, tune shifts: electrons, a reduction of the stability threshold for bunches crossing the transition energy, and possibly slow emittance growth. We summarize the main observations in operation and dedicated experiments, as well as countermeasures including baking, NEG coated warm beam pipes, solenoids, bunch patterns, anti-grazing rings, pre-pumped cold beam pipes, and scrubbing.

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
910365
Report Number(s):
BNL-78049-2007-CP
R&D Project: 18026; KB0202011; TRN: US0704139
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Conference
Resource Relation:
Conference: ECL2 WORKSHOP; CERN, SWITZERLAND; 20070301 through 20070302
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BROOKHAVEN RHIC; ELECTRONS; BEAM DYNAMICS; OPERATION

Citation Formats

FISCHER,W., BLASKIEWICZ, M., HUAN, H., HSEUH, H.C., PTITSYN, V., ROSER, T., THIEBERGER, P., TRBOJEVIC, D., WEI, J., ZHANG, S.Y., and IRISO, U. ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.. United States: N. p., 2007. Web.
FISCHER,W., BLASKIEWICZ, M., HUAN, H., HSEUH, H.C., PTITSYN, V., ROSER, T., THIEBERGER, P., TRBOJEVIC, D., WEI, J., ZHANG, S.Y., & IRISO, U. ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.. United States.
FISCHER,W., BLASKIEWICZ, M., HUAN, H., HSEUH, H.C., PTITSYN, V., ROSER, T., THIEBERGER, P., TRBOJEVIC, D., WEI, J., ZHANG, S.Y., and IRISO, U. Thu . "ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.". United States. doi:. https://www.osti.gov/servlets/purl/910365.
@article{osti_910365,
title = {ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.},
author = {FISCHER,W. and BLASKIEWICZ, M. and HUAN, H. and HSEUH, H.C. and PTITSYN, V. and ROSER, T. and THIEBERGER, P. and TRBOJEVIC, D. and WEI, J. and ZHANG, S.Y. and IRISO, U.},
abstractNote = {Since 2081 MIC has experienced electron cloud effects, which have limited the beam intensity. These include dynamic pressure rises - including pressure instabilities, tune shifts: electrons, a reduction of the stability threshold for bunches crossing the transition energy, and possibly slow emittance growth. We summarize the main observations in operation and dedicated experiments, as well as countermeasures including baking, NEG coated warm beam pipes, solenoids, bunch patterns, anti-grazing rings, pre-pumped cold beam pipes, and scrubbing.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}

Conference:
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  • Since 2001 RHIC has experienced electron cloud effects, which have limited the beam intensity. These include dynamic pressure rises - including pressure instabilities, tune shifts, a reduction of the stability threshold for bunches crossing the transition energy, and possibly incoherent emittance growth. We summarize the main observations in operation and dedicated experiments, as well as countermeasures including baking, NEG coated warm beam pipes, solenoids, bunch patterns, anti-grazing rings, pre-pumped cold beam pipes, scrubbing, and operation with long bunches.
  • The large scale application of non-evaporable getter coating in RHIC has been effective in reducing the electron cloud. Since beams with higher intensity and smaller bunch spacing became possible in operation, the emittance growth is of concern. Study results are reported together with experiences of machine improvements: saturated NEG coatings, anti-grazing ridges in warm sections, and the pre-pumping in cryogenic regions.
  • Beam induced electron multipacting may be among the main reasons for the vacuum pressure rise when circulating high intensity ion and proton beams in RHIC. Latest simulation results are benchmarked with recent experimental observations for RHIC, and compared to other general computer codes. The influence of the electron multipacting to the vacuum properties is also discussed.
  • In RHIC high intensity operation, two types of pressure rise are currently of concern. The first type is at the beam injection, which seems to be caused by the electron multipacting, and the second is the one at the beam transition, where the electron cloud is not the dominant cause. The first type of pressure rise is limiting the beam intensity and the second type might affect the experiments background for very high total beam intensity. In this article, the pressure rises at RHIC are described, and preliminary study results are reported. Some of the unsettled issues and questions aremore » raised, and possible counter measures are discussed.« less