AWAKE - additional equipment

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 source
Along with the metal vapour and helicon sources, the discharge plasma cell is one of the tech- nology options for AWAKE
as described in the Design Report. The discharge cell has significant advantages over the other two, viz. it is scalable to
long distances (i.e. tens of metres and beyond) which is not the case for the metal vapour cell, and although the helicon is
similarly scalable, this is a far more expensive option than the discharge source due to the large amounts of RF needed to
generate the helicon waves. The simple, glass-tube structure of the discharge cell should also make it more amenable to
diagnostic devices (e.g. WP2) which can utilise the open structure of the discharge cell. The work is led by Imperial, with
Nelson 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 that
provides ~300 A at 2 kV. The power supply is based on a prototype built in-house at Imperial. Measurements of the density
uniformity using interferometry are now underway which after completion should demonstrate the feasibility of these
discharges 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.

The main academic beneficiaries are the high-energy physics community, that will be able to assess if there is sufficient
expertise to be able to plan and implement proton drive plasma wakefield experiments, that have the possibility of
overcoming the energy barrier for electron-positron colliders.