Surface production dominating Cs-free H− ion source for high intensity and high energy proton accelerators

Abstract

Articles you may be interested inInfluence of electric field penetration by a three-electrode beam extraction system on hydrogen negative ion source plasmaa) Rev. Sci. Instrum. 85, 02A720 (2014); 10.1063/1.4833918 Effect of non-uniform electron energy distribution function on plasma production in large arc driven negative ion sourcea) Rev. Sci. Instrum. 83, 02A719 (2012); 10.1063/1.3673485 A survey of optimal filament shape in a Japan Proton Accelerator Research Complex H − ion sourcea) Rev. Sci. Instrum. 81, 02A717 (2010); 10.1063/1.3277158 High-intensity ion sources for accelerators with emphasis on H − beam formation and transport (invited)a) Rev. Sci. Instrum. 81, 02B311 (2010);

Cesiation in highly efficient surface plasma sources

“…. [7,20]. This activation from contamination was so perfect that the efficiency of H À generation was not improved significantly by standard cesiation after cracking the cesium ampoule.…”

“…Later, increased emission current density was produced in a multicusp H À source with a hot LaB 6 cathode [20,21], where surface-plasma H À generation was enhanced by high current discharge with negative biasing of the plasma electrode during electrode activation. This enhancement can be explained as due to the decrease of the surface work function connected with La deposition.…”

Rod-filter-field optimization of the J-PARC RF-driven H− ion source

“…The electrons extracted simultaneously with the H¯ ion beam are bent to the electron dump on the EE by the electron suppression permanent magnets installed in the EE. The ejection angle of the H¯ ion beam, which is produced by the rod-filter and electron-suppression fields, can be corrected with an alignment error of about 50m by the ejection angle correction electromagnet [10]. The ejected H¯ ion beam is focused by a solenoid magnet into the chamber for emittance monitors and a Faraday-cup (FC).…”

Operation of RF driven negative ion source in a pure-hydrogen mode

“…It was revealed, that a few seed of cesium to RF driven source increases the surface production of negative ions for a long time [7]. An intense pulsed inductively-driven RF sources demonstrate the high rate of negative ion production in a pure-hydrogen mode with no external alkali additives [2,[8][9][10]], but the rate of H-ions production in these sources depends on the source conditioning time [8][9][10], what is unusual for the pure-volume processes of negative ion generation. It was suggested, that the release of alkali impurities like potassium or sodium from the ceramics could be a reason of the source conditioning and negative ion yield increase [2].…”