TY - JOUR
T1 - Experimental investigation of an optimum configuration for a high-voltage photoemission gun for operation at ≥500kV experimental investigation of an optimum ... Nobuyuki Nishimori et al.
AU - Nishimori, Nobuyuki
AU - Nagai, Ryoji
AU - Matsuba, Shunya
AU - Hajima, Ryoichi
AU - Yamamoto, Masahiro
AU - Honda, Yosuke
AU - Miyajima, Tsukasa
AU - Iijima, Hokuto
AU - Kuriki, Masao
AU - Kuwahara, Makoto
PY - 2014/5/19
Y1 - 2014/5/19
N2 - We demonstrated the generation of a 500-keV electron beam from a high dc voltage photoemission gun for an energy recovery linac light source [N. Nishimori et al., Appl. Phys. Lett. 102, 234103 (2013)]. This demonstration was achieved by addressing two discharge problems that lead to vacuum breakdown in the dc gun. One is field emission generated from a central stem electrode. We employed a segmented insulator to protect the ceramic insulator surface from the field emission. The other is microdischarge at an anode electrode or a vacuum chamber, which is triggered by microparticle transfer or field emission from a cathode electrode. An experimental investigation revealed that a larger acceleration gap, optimized mainly to reduce the surface electric field of the anode electrode, suppresses the microdischarge events that accompany gas desorption. It was also found that nonevaporable getter pumps placed around the acceleration gap greatly help to suppress those microdischarge events. The applied voltage as a function of the total gas desorption is shown to be a good measure for finding the optimum dc gun configuration.
AB - We demonstrated the generation of a 500-keV electron beam from a high dc voltage photoemission gun for an energy recovery linac light source [N. Nishimori et al., Appl. Phys. Lett. 102, 234103 (2013)]. This demonstration was achieved by addressing two discharge problems that lead to vacuum breakdown in the dc gun. One is field emission generated from a central stem electrode. We employed a segmented insulator to protect the ceramic insulator surface from the field emission. The other is microdischarge at an anode electrode or a vacuum chamber, which is triggered by microparticle transfer or field emission from a cathode electrode. An experimental investigation revealed that a larger acceleration gap, optimized mainly to reduce the surface electric field of the anode electrode, suppresses the microdischarge events that accompany gas desorption. It was also found that nonevaporable getter pumps placed around the acceleration gap greatly help to suppress those microdischarge events. The applied voltage as a function of the total gas desorption is shown to be a good measure for finding the optimum dc gun configuration.
UR - http://www.scopus.com/inward/record.url?scp=84902106458&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84902106458&partnerID=8YFLogxK
U2 - 10.1103/PhysRevSTAB.17.053401
DO - 10.1103/PhysRevSTAB.17.053401
M3 - Article
AN - SCOPUS:84902106458
VL - 17
JO - Physical Review Special Topics - Accelerators and Beams
JF - Physical Review Special Topics - Accelerators and Beams
SN - 1098-4402
IS - 5
M1 - 053401
ER -