Author: Wilcox, C.C.
Paper Title Page
TUPC147 A Micro-Channel Plate Based Gas Ionization Profile Monitor with Shaping Field Electrodes for the ISIS H− Injector 1371
 
  • P.G. Barnes, G.M. Cross, B.S. Drumm, S.A. Fisher, S.J. Payne, A. Pertica, C.C. Wilcox
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  Beam pro­file mea­sure­ments with­in the ISIS H− in­jec­tor line are achieved using de­struc­tive de­vices such as mov­ing wire scan­ners. To avoid dam­age to the wires, mea­sure­ments are made with the in­jec­tor op­er­at­ing on re­duced power. This paper re­ports the de­vel­op­ment of a Mi­cro-Chan­nel Plate based pro­file mon­i­tor which al­lows beam mea­sure­ments to be made under nor­mal op­er­at­ing con­di­tions. The mon­i­tor pro­duces pro­files by mea­sur­ing the +ion cur­rent re­sult­ing from the in­ter­ac­tion of the H− beam with the sur­round­ing resid­u­al gas. The 32 chan­nel Mi­cro-Chan­nel Plate is mount­ed on a ro­tat­ing arm to en­able it to be po­si­tioned par­al­lel to the beam for cal­i­bra­tion (all chan­nels then mea­sure the same +ion cur­rent) and per­pen­dic­u­lar to the beam for pro­file mea­sure­ments. A 15kV drift field is used to­geth­er with field shap­ing elec­trodes to en­sure a flat elec­tric field gra­di­ent across the mon­i­tor, there­by min­imis­ing dis­tor­tion of the pro­file due to the elec­tric field. This paper de­tails all as­pects of the de­sign and con­struc­tion of this pro­file mon­i­tor. Beam pro­files are com­pared to pre­vi­ous wire scan­ner re­sults. Shap­ing field up­grades are dis­cussed to im­prove the lon­gi­tu­di­nal field shape.