Plasma wakefield acceleration - bridging fund

请求在2014年10月1日至2015年9月30日期间桥接AWAKE-UK，并根据建议限制为固定现金延续。这使我们能够保持我们在目前资助领域的努力，尽管为了交付和继续领导，在加速器审查结果公布后，将要求更大的赠款。在过渡期内，目前在职的PDRA将继续保留，其他资源用于基本消耗品和参加协作会议的差旅以及主要访问CERN。帝国将致力于WP 4：等离子体放电源。目标总结如下：2.4 WP 4：放电等离子体源与金属蒸汽和螺旋源一起，放电等离子体单元是AWAKE的技术选项之一，如设计报告所述。放电单元相对于其他两个具有显著的优点，即，其可扩展到长距离（即，数十米及更远），而金属蒸气单元的情况并非如此，并且尽管螺旋波是类似地可扩展的，但由于产生螺旋波所需的大量RF，这是比放电源昂贵得多的选择。放电单元的简单的玻璃管结构也应该使其更适合于可以利用放电单元的开放结构的诊断设备（例如WP 2）。这项工作由帝国领导，纳尔逊洛佩斯是清醒任务的领导者，与里斯本合作。在目前的赠款期间，已经建立了原型，具有10 mm直径1.5 m长的电池，其基于1.6微秒脉冲放电以约0.3 Hz的频率工作，在2 kV下提供约300 A。该电源是基于帝国内部制造的原型。目前正在使用干涉测量法测量密度均匀性，完成后应证明这些放电在接近唤醒所需配置中的可行性。明年要解决的关键问题是：* 获得玻璃管中的气压稳定性; * 获得所需的等离子体均匀性;* 测量所需的等离子体密度;* 确保高压设置的可靠性;* 符合CERN标准;* 开发更长（最长10米）的原型。

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 sourceAlong 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.