Plasma wakefield acceleration - bridging fund

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics


A request is made for bridging AWAKE-UK for the period 1 October 2014 - 30 September 2015, restricting to a flat-cash continuation as recommended. This allows us to maintain our effort in the currently funded areas although for delivery and continued leadership, a more significant grant will be requested after the outcome of the accelerator review is known. During the bridging period, PDRAs currently in post will be retained, with other resources used for essential consumables and travel to attend Collaboration Meetings and visits primarily to CERN.

Imperial will 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.

Planned Impact

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.


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Bracco C (2016) AWAKE: A Proton-Driven Plasma Wakefield Acceleration Experiment at CERN in Nuclear and Particle Physics Proceedings

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Caldwell A (2016) Path to AWAKE: Evolution of the concept in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Gschwendtner E (2016) AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Description Self-modulation of the SPS beam at CERN seen which is due to driving of plasma wave

Electron acceleration with the self-modulated beam was also observed, but we were not involved due to lack of funding.
Exploitation Route Next stage of AWAKE experiment is in planning,

we are actively seeking to be involved as the discharge sources we have developed could be integral to future experiments.
Sectors Government, Democracy and Justice,Other

Description EuPRAXIA
Amount £132,142 (GBP)
Funding ID 653782 
Organisation European Commission 
Department Horizon 2020
Sector Public
Country European Union (EU)
Start 11/2015 
End 10/2019
Description Talk to Imperial College PhysSoc 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Talked about novel plasma accelerators to undergraduate students, which many reported was the first time they had heard of the concept.
Year(s) Of Engagement Activity 2018