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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 dark current from Cs2Te layer during the gun operation is about 50 nA, and the thermal emittance measured in SRF gun is 0.7 μrad/r(mm).

 

Table 1: Cs2Te Cathode operated in SRF gun

Cathode

No.

Operation

Days

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%

 

Quantum Efficiency over the Lifetime of Cs2Te Cathodes in the SRF Gun.

Quantum Efficiency over the Lifetime of Cs2Te Cathodes in the SRF Gun.

Reference:

[1] R. Xiang, et al., Cs2Te normal conducting photocathodes in the superconducting rf gun, Phys. Rev. ST Accel. Beams 13, 043501 (2010)