New experimental measurements of electron clouds in ion beams with large tune depression

Conference · Thu Mar 16 00:00:00 EST 2006

OSTI ID:885133

Molvik, A W; Covo, M K; Cohen, R H; Friedman, A; Bieniosek, F M; Leister, C M; Seidl, P A; Vay, J

We study electron clouds in high perveance beams (K = 8E-4) with a large tune depression of 0.2 (defined as the ratio of a single particle oscillation response to the applied focusing fields, with and without space charge). These 1 MeV, 180 mA, K+ beams have a beam potential of +2 kV when electron clouds are minimized. Simulation results are discussed in a companion paper [J-L. Vay, this Conference]. We have developed the first diagnostics that quantitatively measure the accumulation of electrons in a beam [1]. This, together with measurements of electron sources, will enable the electron particle balance to be measured, and electron-trapping efficiencies determined. We, along with colleagues from GSI and CERN, have also measured the scaling of gas desorption with beam energy and dE/dx [2]. Experiments where the heavy-ion beam is transported with solenoid magnetic fields, rather than with quadrupole magnetic or electrostatic fields, are being initiated. We will discuss initial results from experiments using electrode sets (in the middle and at the ends of magnets) to either expel or to trap electrons within the magnets. We observe electron oscillations in the last quadrupole magnet when we flood the beam with electrons from an end wall. These oscillations, of order 10 MHz, are observed to grow from the center of the magnet while drifting upstream against the beam, in good agreement with simulations.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 885133
• Report Number(s): UCRL-CONF-219887; TRN: US0603782
• Resource Relation: Conference: Presented at: 39th ICFA Advanced Beam Dynamics Workshop, High Intensity Highh Brightness Hadron Beams (HB2006), Tsukuba, Japan, May 29 - Jun 02, 2006
• Country of Publication: United States
• Language: English

Related Subjects

29 ENERGY PLANNING
POLICY AND ECONOMY
43 PARTICLE ACCELERATORS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAM DYNAMICS
BRIGHTNESS
CERN
CLOUDS
DESORPTION
ELECTRODES
ELECTRON SOURCES
ELECTRONS
ELECTROSTATICS
FLOODS
FOCUSING
HADRONS
ION BEAMS
MAGNETIC FIELDS
MAGNETS
OSCILLATIONS
QUADRUPOLES
SIMULATION
SOLENOIDS