AWAKE - additional equipment

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Additional equipment to support Imperial's work on WP4: Plasma Discharge Source. A summary of the objectives are given below:2.4 WP4 : Discharge plasma sourceAlong with the metal vapour and helicon sources, the discharge plasma cell is one of the tech- nology options for AWAKEas described in the Design Report. The discharge cell has significant advantages over the other two, viz. it is scalable tolong distances (i.e. tens of metres and beyond) which is not the case for the metal vapour cell, and although the helicon issimilarly scalable, this is a far more expensive option than the discharge source due to the large amounts of RF needed togenerate the helicon waves. The simple, glass-tube structure of the discharge cell should also make it more amenable todiagnostic devices (e.g. WP2) which can utilise the open structure of the discharge cell. The work is led by Imperial, withNelson Lopes the AWAKE task leader, in collaboration with Lisbon. During the current grant, prototypes have been built,with a 10mm diameter 1.5m long cell operated at ~0.3Hz based on a 1.6 microsecond pulsed electrical discharge thatprovides ~300 A at 2 kV. The power supply is based on a prototype built in-house at Imperial. Measurements of the densityuniformity using interferometry are now underway which after completion should demonstrate the feasibility of thesedischarges in a configuration close to the that needed for AWAKE. Longer cells are also in preparation.The key issues to be worked on during the next year are:* Obtain gas pressure stability in the glass tube;* Obtain the required plasma uniformity;* Measure the required plasma density;* Ensure HV setup reliability;* Comply with CERN standards;* Development of longer (up to 10 m) prototypes.