| Paper | Title | Page |
|---|---|---|
WG1017 |
Photocathode R&D for High Average Current ERL Photoinjectors at Daresbury Laboratory | |
|
||
| Significant effort has been expended over several years at Daresbury on R&D in the procedures underlying the preparation of the GaAs photocathode family for use as electron sources in ERL injectors. Having established robust chemical and thermal cleaning processes, and carried out lifetime studies on activated photocathodes by deliberately poisoning them, we will present data showing the different levels of quantum efficiency achievable using a heterostructure photocathode when activating with both oxygen and nitrogen-triflouride. The next goal in our research programme is to investigate the ultimate emittance achievable from the GaAs photocathode family. One option under consideration is the cooling of photocathodes to Liquid Nitrogen (LN) temperature, and two experimental programmes have been instigated on this basis. The first is intended to measure the energy spread of electrons emitted from the photocathode, and observe how the energy spread evolves during photocathode degradation. The second programme aims to characterise photocathode emittance and response time in a relatively low energy 160 kV photocathode gun. | ||
|
Slides WG1017 [1.586 MB] | |
WG2003 |
Investigation of Beam Dynamics with Not-ideal Electron Beam on ALICE ERL | |
|
||
| ALICE, an energy recovery linac based accelerator, drives an IR-FEL and is a source of broadband coherently enhanced THz radiation. It also serves as a test-bed for various accelerator physics experiments. The beam dynamics, both transverse and longitudinal, is therefore of primary importance. The overview of the machine lattice and the design beam dynamics are described. As with many other machines in this class, the electron beam in ALICE is not always of perfect quality. This is aggravated by the fact that, currently, the quantum efficiency map of the photocathode is not fully uniform and the operating voltage of the HV DC photoelectron gun is only 230kV compared to design value of 350kV. Results of the experimental investigation of the beam dynamics and data analysis at these conditions are presented. The emphasis is made on understanding the physics that may affect the overall beam quality and on interpretation and analysis of experimental data. | ||
|
|
Slides WG2003 [2.330 MB] | |
WG2023 |
Longitudinal Dynamics in the ALICE Injection Line | |
|
||
| The ALICE Energy Recovery Linac at Daresbury Laboratory drives an IR-FEL and serves as a source of coherent THz radiation. For these uses, the demands on transverse emittance are quite relaxed, however, the longitudinal dynamics need to be carefully controlled. The IR-FEL demands bunch length less than 1 ps and energy spread around 100 keV. The amount of THz produced is also strongly dependent on the bunch length. The ALICE injector consists of a DC photocathode gun, currently operating at 230 keV, followed by a single-cell buncher cavity and a superconducting booster module which accelerates the beam up to 6.5 MeV. An injection line transports this relatively low energy beam for around 13 m, including a number of bends, prior to injection into the main linac. We observe appreciable development in the longitudinal phase space of the beam in this injection line. The longitudinal dynamics of the beam in the first acceleration stage and along the long injection line will be discussed with reference to simulations and measurements. | ||
|
|
Slides WG2023 [2.285 MB] | |