Emittance Reduction between EBIS LINAC and Booster by Electron Beam Cooling; Is Single Pass Cooling Possible?

Abstract

Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in less than one meter.

Issues Concerning High Current Low Energy Electron Beams Required for Ion Cooling between EBIS LINAC and Booster

“…A number of pertinent physics issues were evaluated in previous notes 1 . Those analyses are still valid.…”

“…It was suggested 1 to use an electron beam for single-pass cooling of the ion beam end of the EBIS-RFQ-LINAC system. Expected ion beam parameters 2 , based on design, at the exit of the EBIS-RFQ-LINAC system are: energy 2 MeV/u, momentum , beam diameter 1 cm, and gold ion charge state Au +32 , with ion density 2 at the LINAC exit n i =8x10 7 cm -3 .…”

Part II/Addendum Electron Beam Cooling between EBIS LINAC and Booster; Is Single Pass Cooling Possible?

“…Cooling time (and ion heating) values computed in the previous note 1 are repeated for this case, in which ion transverse velocity spread is dominant. Parkhomchuk's empirical formula 8 and formulas 9,10 based on plasma physics test particle model [5][6][7] are used to compute cooling time.…”

Issues concerning high current lower energy electron beams required for ion cooling between EBIS LINAC and booster

“…It was suggested 1 to use an electron beam for single-pass cooling of the ion beam end of the EBIS-RFQ-LINAC system. Expected ion beam parameters 2 , based on design, at the exit of the EBIS-RFQ-LINAC system are: energy 2 MeV/u, momentum spread tlpt=10- 3 , and tipi =5x10-3 , beam diameter 1 cm, and gold ion charge state AU+ 32 , with ion density2 at the LINAC exit nj=8xl0 7 cm-3 • For electrons to match ion velocity, their energy U must be about 1 KeV (actually slightlr more than 1.098 KeV).…”