Test EBIS operation and componentdevelopment for the RHIC EBIS*

Abstract

Most design goals of the BNL Test EBIS Project have been exceeded and we areconfident that an EBIS meeting RHIC requirements can be built. Achieved parameters include10 A electron beam current, ion charge state above Au32+, and greater than 55 nC total extractedion charge. The Test EBIS utilizes the full electron beam power but has only half the trap lengthand operates at a reduced duty factor compared with an EBIS for RHIC, which would produce atleast 85 nC total ion charge in 10–40 microsecond pulses, containing ~3 × 109 particles/pulse ofAu32+ ions. Normalized rms emittance values for 1–3 mA extracted ion beams have been in therange of 0.08–0.1 pi mm mrad. Present development of the source is focused on establishingoperational reliability and facilitating future upgrades in ion intensity and species, since themajor emphasis is now on integrating the EBIS into a pre-injector facility, including an RFQ andlinac. Recent progress towards this goal includes the following: (1) An IrCe electron guncathode and modified anode have been installed in an electron gun chamber separable from thesource ionization region by a gate valve. A very low loss 10 A, electron beam has beenpropagated with the new configuration, with 100 kW peak power dissipation at the electroncollector. (2) A new electron collector power supply configuration has been tested which canlower the cost compared to our present setup, while improving the stability of the electron beamlaunch. This is an important first step towards placing the EBIS on a nominal 50 kV platform,necessary for efficient highly charged ion transport to the RFQ. (3) A hollow cathode ion sourceobtained from CEA Saclay, has been tested and is being installed. This will allow us toprovide a variety of ion species to the RHIC and NASA Space Radiation Laboratory facilities,and is valuable at the present project stage for beamline development and emittance studies ofheavy and light ion beams of highly charged ions from the EBIS. (4) An electron collector forRHIC has been designed which would allow operation exceeding 10 A electron beams at 100%duty factor. The RHIC collector design could allow upgrades to 300 kW electron beampower. (5) Controls for pulse to pulse switching and diagnostics for charge state and chargefraction verification have been developed.