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WG1011 |
Performance of the ALICE ERL Photoinjector Photocathode Gun | |
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| Accelerators and Lasers In Combined Experiments (ALICE) is a 35 MeV energy-recovery linac at Daresbury Laboratory. The ALICE electron beam drives an IR-FEL and THz light sources. The ALICE photoinjector gun is a variant of the JLab IR-FEL design, operating at 350 kV DC with a GaAs cathode. Photocathode activation is carried out in-situ, normally using caesium and oxygen, though nitrogen triflouride (NF3) has been used for a limited period. An upgrade to the ALICE photoinjector gun has been designed and partially constructed. Based on an external state-of-the-art Photocathode Preparation Facility (PPF), it offers an excellent environment for photocathode preparation, activation and operation. This paper reviews the current ALICE photocathode gun performance, presenting beam parameters obtained with GaAs photocathodes and outlines future plans for improving the gun beam quality. We will also compare photocathode performance in the ALICE gun when activated using both O2 and NF3 as the oxidant to that demonstrated in the PPF. | ||
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Slides WG1011 [4.542 MB] | |
WG2003 |
Investigation of Beam Dynamics with Not-ideal Electron Beam on ALICE ERL | |
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| 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. | ||
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Slides WG2003 [2.330 MB] | |
WG2023 |
Longitudinal Dynamics in the ALICE Injection Line | |
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| 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. | ||
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Slides WG2023 [2.285 MB] | |
WG3007 |
ALICE: Current Status and Developments | |
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| ALICE (Accelerators and Lasers In Combined Experiments) is a multifunctional ERL based R&D facility that operates in various regimes depending on the project undertaken (beam energy 10-28MeV, bunch charge 20-100pC, train length from a single bunch to 100us). Several experiments are conducted on ALICE in non-energy recovery mode. The variety of operational regimes presents a challenge in setting up the machine but also allows to conduct studies in a wide range from accelerator physics to life sciences. The current status of the machine and recent developments are described. These include IR-FEL lasing, generation and applications of coherently enhanced THz radiation, development of electro-optic diagnostic techniques, optical high precision timing distribution system, and digital low-level RF control system. Other projects are also briefly discussed including a recent demonstration of acceleration in EMMA, the first non-scaling FFAG, for which ALICE serves as an injector. | ||
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Slides WG3007 [6.041 MB] | |