Standard Cs2Te Cathode
Cs2Te is a p-type semiconductor with the work function of 3.5 eV. Because of its good efficiency and robustness in rf field, Cs2Te has been chosen as the standard photocathode for the SRF guns at HZDR. Up to now, more than 10 Cs2Te photocathodes were operated in the SRF gun I and SRF gun II. The typical quantum efficiency (QE) is 1% and the dark current from Cs2Te layer during the gun operation is about 50 nA.
Table 1: Cs2Te Cathode operated in SRF gun
Cathode No. |
Operation days in gun |
Charge |
QE in gun |
#090508Mo |
30 |
< 1 C |
0.05% |
#070708Mo |
60 |
< 1 C |
0.1% |
#310309Mo |
109 |
< 1 C |
1.1% |
#040809Mo |
182 |
< 1 C |
0.6% |
#230709Mo |
56 |
< 1 C |
0.03% |
#250310Mo |
427 |
35 C |
1.0% |
#090611Mo |
65 |
< 1 C |
1.2% |
#300311Mo |
76 |
2 C |
1.0 % |
#170412Mo |
447 |
264 C |
0.6 % |
# Cs2Te 2016.3 |
14 |
0.8% |
|
# Cs2Te 2017.3 |
16 |
0.88% |
|
# Cs2Te_Cu_2020.3.4 |
56 |
1.4% |
|
#Cs2Te_Cu_2020.2.26 |
1.5% |
||
#Cs2Te_Cu_2019.11. |
1.5% |
Reference:
[1] R. Xiang, et al., Cs2Te normal conducting photocathodes in the superconducting rf gun, Phys. Rev. ST Accel. Beams 13, 043501 (2010)