Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
The Conceptual Design of 4GLS at Daresbury Laboratory
GLS is a novel next generation proposal for a
UK national light source to be sited at Daresbury
Laboratory, based on a superconducting
energy recovery linac (ERL) with both
J.A. Clarke, J.A. Clarke (Cockcroft Institute) E.A. Seddon (CCLRC/
DL/SRD)
high average current photon sources (undulators and bending magnets) and three high peak current free electron
lasers. Key features are a high gain, seeded FEL amplifier to generate XUV radiation and the prospect of advanced
research arising from unique combinations of sources with femtosecond pulse structure. The conceptual design is
now completed and a CDR recently published. The 4GLS concept is summarised, highlighting how the significant
design challenges have been addressed, and the project status and plans explained.
Energy Recovery Linac Prototype DC Photocathode Gun
CCLRC Daresbury Laboratory has undertaken
the manufacture and assembly of the K. Fayz (CCLRC/DL)
500kV DC photocathode gun for the ERLP.
The gun design is a property of the Thomas Jefferson Laboratory. Permission was given to Daresbury Laboratory to
copy or redesign the injector components. It will operate at a vacuum pressure of 10-11mBar, a nominal accelerating
voltage of 350kV and a bunch charge of 80 pC. The manufacture of the gun incorporates the use of specialized materials
such 304L vacuum arc re-melt cross forged stainless steel and the use of hand polishing techniques to minimise
the risk of arcing . The Daresbury design incorporates a single controlled resistivity ceramic with a resistivity of
6x1012ohm, a length of 600 mm and a diameter of 250mm. The gun and HV supply are housed in connecting pressure
tanks held at 1 Bar via a purpose designed SF6 gas system. Engineering software tools including Pro/Engineer CAD
modeling and ANSYS FEA software where used to adapted the design to Daresbury requirements. It currently is in
its final assembly stage, in a class 10 clean room, expected to become operational in April 2006. The work has been
done in collaboration with the Jefferson Laboratory.
Status of theVacuum System Design for the Energy Recovery Linac Prototype (ERLP)
Project at Daresbury Laboratory
The ERLP is an electron accelerator currently
being built at Daresbury Laboratory. The
project is a test bed for the technology required
to build the 4th Generation Light
K.J. Middleman, J.D. Herbert, O.B. Malyshev, R.J. Reid (CCLRC/
DL/ASTeC)
Source (4GLS). The project is under way and commissioning is due to start this summer. The vacuum requirements
for the ERLP are 5x 10 -8 mbar in the beam transport system and 10 -11 mbar in the photoinjector and superconducting
cavities. These are the most critical elements in the vacuum design and are crucial to the performance of the
accelerator. The photoinjector and superconducting cavities require low particulate densities to minimise particulate
contamination which leads to enhanced field emission of electrons which can significantly reduce the performance
of the accelerator. Experience elsewhere */** shows that the amount of cryosorbed material on the inside of the
superconducting cavities can also influence their performance. This paper presents the techniques used to calculate
the cryodeposition of contaminant layers on the RF cavities and the methods used to minimise particle densities inside
the vacuum envelope. In addition pressure profiles for other elements of the prototype machine will be detailed.
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