MOIBCC002
IKP, Mainz, Germany
HIM, Mainz, Germany
For high average electron beam currents the length of the electron bunches must match the acceptance of the accelerator. At Johannes Gutenberg-Universität we are able to measure the longitudinal pulse responses of different photocathodes: negative electron affinity (NEA) types and positive electron affinity (PEA) types. With NEA (Cs:GaAs), the pulse response depends on the wavelength of photoexcitation and show at 800nm a long and relatively intense tail whereas at 400nm a similar shape but with orders of magnitude lower intensity is observed. In comparison to this distribution, PEA pulse responses (K2CsSb) show a similar shape as well but another order of magnitude less intensity than NEA in the blue excitation.
IKP, Mainz, Germany
HIM, Mainz, Germany
The interest in multi alkali antimonide photocathodes, e.g. K2CsSb, for future ERL projects like BERLinPro (Berlin Energy Recovery Linac Prototype) and MESA (Mainz Energy-Recovering Superconducting Accelerator) has grown in recent years. In particular for the case of RF-sources the investigation of the time response is of great importance. In Mainz we are able to synthesize these kinds of photocathodes and investigate their pulse response at 1 picosecond level using a radio frequency streak method. We present on the one hand the cathode plant which is used for synthesizing the multi alkali antimonide photocathodes and on the other hand first measurements showing pulse responses of K2CsSb at 400 nm laser wavelength. Furthermore, an analyzing chamber has been installed, which allows investigation of lifetime under laser heating and in-situ measurements of the work function using a UHV Kelvin Probe.
IKP, Mainz, Germany
The electron source concept SPOCK (Short Pulse Source at KPH) is a 100kV DC source design with variable extraction gradient. Due to its triode inspired design the extraction gradient can be reduced for e.g. investigations of cathode physics, but also enhanced to mitigate space charge effects. In the framework of the MESA-Project (Mainz Energy-Recovering Superconducting Accelerator) its design has been further optimized to cope with space charge dominated electron beams. Although it injects its electron beams directly into the LEBT matching section, which excludes any adjustments of the electron spin, the source SPOCK will allow higher bunch charges than the MESA standard source.