Discharge plasmas as a medium a collider based on wakefield accelerators

尾波场加速器利用等离子体产生的巨大磁场将粒子加速到高能。能量增益&gt；gev现在通常在世界各地的激光设施中生产，距离只有几厘米。然而，即使是最强大的激光脉冲也能获得相对较低的能量，这对粒子的能量增益是一个限制。相比之下，欧洲核子研究中心可用的离子束的能量超过10‘S千焦耳(如果不是更多的话)。这意味着，粒子不是加速超过厘米，而是有可能加速超过数十米，如果不是数百米的话。这将产生一种与高能物理实验相关的加速器。欧洲核子研究中心的觉醒实验已经利用SPS光束产生了令人兴奋的结果，展示了10米电池中电子的2GeV能量增益。为了克服SPS光束太长而不能理想地驱动尾波场的事实，人们使用了一种称为自调制的过程来在SPS光束中产生与尾波场共振的小光束。这是在RB细胞中由激光启动的，当质子束穿过等离子体时，激光使等离子体电离。然而，电离激光的使用限制了加速长度。我们建议(与里斯本IST一起)使用放电等离子体，使加速长度远远超过目前可用的10米。但对于受控加速，等离子体密度必须控制在1%以上，而且可能还需要有等离子体密度的斜坡来优化加速过程。因此，在这个项目中，我们将使用我们在Blackett实验室中拥有的原型放电来诊断和模拟大规模(米长)等离子体的产生。我们还将对SPS质子束与加速器级的相互作用进行建模。然后，我们将进一步优化等离子体轮廓，以提高加速度。将进行这些调查，以期在欧洲核子研究中心未来的唤醒运行中既实施出院又进行诊断。

Wakefield accelerators use the immense fields produced in plasmas to accelerate particles to high energy. Energy gains > GeV are now routinely produced at laser facilities around the world over only centimetre distances. However, the relatively low energy available in even the most powerful laser pulse is a limitation on the particle's energy gain. By contrast the ion beams available at CERN have energy that exceeds 10's of kJ (if not more). This means that instead of accelerating particles over centimetres, there is the potential to accelerate over tens if not hundreds of metres. This would produce an accelerator relevant to high-energy physics experiments.The AWAKE experiment at CERN has already produced exciting results using the SPS beam demonstrating 2 GeV energy gain of electrons in a 10m cell. To overcome the fact that the SPS beam is too long to ideally drive a wakefield, a process called self-modulation has been used to produce beamlets within the SPS beam that are resonant with a wakefield. This is initiated in a Rb cell by a laser that ionises the plasma as the proton beam is passing through it. However, the use of the ionising laser puts a limit on the acceleration length.We have proposed (along with IST Lisbon) using a discharge plasma that would enable acceleration lengths well in excess of the 10m available now. But for controlled acceleration the plasma density must be controlled to better than 1%, and it may be further necessary to have ramps in plasma density to optimise the acceleration process. Hence, in this project, we will look to diagnose and model the generation of large scale (metre long) plasmas, using the prototype discharge we have here in the Blackett Lab. We will also model the interaction of the SPS proton beam with our accelerator stage. We will then look further to optimise the plasma profile to improve the acceleration. These investigations will be performed with a view to implementing both the discharge and the diagnostics on future runs of AWAKE at CERN.