Laser-based selective preionization of plasma wakefield accelerator stages

基于激光的等离子体尾场加速器级选择性预电离

• 批准号: 2277943
• 金额: --
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2277943
• 关键词: Laser; based; selective; preionization; plasma

Particle beam-driven plasma wakefield acceleration (PWFA) is an area of strongly increasing interest in the world-wide accelerator community. Next to large accelerator centres such as SLAC, laser-plasma accelerators such as at the SCAPA centre at University of Strathclyde or the CALA centre at LMU Munich can also engage, by using electron beams from laser-plasma-accelerators (LWFA) as drivers for the PWFA stage [1,2,3]. Generation of wide preionized plasma channels as medium for PWFA is a key task for production of electron beams with high energies and high-quality [4,5]. A further key feature is to ionize only one component in a multi-component gas-plasma, such that an ionized component is available for realization of plasma photocathodes. These are based on the feature that electron-driven plasma wakefield acceleration does not require excessive peak electric driver fields to excite strong plasma waves, due to its unipolar electric drive beam field distribution. The peak electric field of electron beams required capable to excite such waves is many orders of magnitude lower than those of high power laser pulses due to their oscillating electric field structure. This feature allows to decouple wake excitation from electron bunch injection by exploiting species of significantly different tunnelling ionization thresholds such as hydrogen and helium. A laser pulse with peak electric fields locally exceeding that of the high ionization threshold medium can therefore be exploited to release and inject electrons in a controlled way at arbitrary spatiotemporal positions. The chief attraction of this is that plasma cathodes can be realized which allow controlled and highly tunable injection of electron populations with extremely low so-called electron beam emittance and therefore ultrahigh brightness, many orders of magnitude better than state-of-the-art. Such capabilities may be transformative for coherent and incoherent photon science sources, high field and high energy physics. In turn, this means that selective ionization of the low ionization threshold component and the high ionization threshold component is required. This includes preionization of the low ionization threshold component uniformly in a wide and long region, shaping of plasma upramps and downramps, as well as locally very confined ionization of the higher ionization threshold component for plasma photocathode injection. This is the core R&D theme of this PhD and implies two main objectives: - Selective laser-based preionization of low-ionization threshold media such as hydrogen. The aim here is an up to metre-long plasma channel with width up to a millimetre, without hot spots which would ionize relevant higher ionization threshold media - Laser-based localized tunneling ionization of high-ionization threshold media such as helium- Metrology of incoming electron and laser pulses, plasma medium and produced electron pulsesThe project is realized in a European collaboration with LMU as main partner. [1] Hidding, B. .. Karsch, S. et al., Monoenergetic Energy Doubling in a Hybrid Laser-Plasma Wakefield Accelerator, Phys. Rev. Lett. 104, 195002 (2010)[2] Direct observation of plasma waves and dynamics induced by laser-accelerated electron beams, M. F. Gilljohann .. B. Hidding .. S. Karsch, Physical Review X 9, 011046 (2019)[3] T. Kurz, T. Heinemann et al., Demonstration of a compact plasma accelerator powered by laser-accelerated electron beams, arXiv:1909.06676[4] G.G. Manahan .. Hidding, B., Single-stage plasma-based correlated energy spread compensation for ultrahigh 6D brightness electron beams, Nat. Communications 8, 15705 (2017)[5] A. Deng .. Hidding, B., Electron bunch generation from a plasma photocathode, Nat. Physics (2019)

粒子束驱动等离子体尾场加速 (PWFA) 是全球加速器界日益关注的一个领域。除了 SLAC 等大型加速器中心之外，斯特拉斯克莱德大学的 SCAPA 中心或慕尼黑慕尼黑大学的 CALA 中心等激光等离子体加速器也可以参与其中，通过使用来自激光等离子体加速器 (LWFA) 的电子束作为驱动器PWFA 阶段 [1,2,3]。产生宽预电离等离子体通道作为 PWFA 的介质是产生高能量和高质量电子束的关键任务 [4,5]。另一个关键特征是仅电离多组分气体等离子体中的一种组分，使得电离的组分可用于实现等离子体光电阴极。这些都是基于电子驱动等离子体尾场加速由于其单极电驱动束场分布而不需要过多的峰值电驱动场来激发强等离子体波的特点。由于其振荡电场结构，能够激发这种波所需的电子束的峰值电场比高功率激光脉冲的峰值电场低许多数量级。该功能允许通过利用具有显着不同的隧道电离阈值的物质（例如氢和氦）来将尾流激发与电子束注入解耦。因此，可以利用峰值电场局部超过高电离阈值介质的激光脉冲，以受控方式在任意时空位置释放和注入电子。其主要吸引力在于可以实现等离子体阴极，其允许受控且高度可调的电子群注入，具有极低的所谓电子束发射率，因此具有超高亮度，比现有技术好许多数量级。这种能力对于相干和非相干光子科学源、高场和高能物理学来说可能是变革性的。反过来，这意味着需要低电离阈值成分和高电离阈值成分的选择性电离。这包括在宽而长的区域中均匀地预电离低电离阈值成分、等离子体上坡道和下坡道的整形，以及用于等离子体光电阴极注入的高电离阈值成分的局部非常有限的电离。这是本博士的核心研发主题，意味着两个主要目标： - 低电离阈值介质（例如氢气）的选择性激光预电离。这里的目标是一个长达一米、宽度可达一毫米的等离子体通道，没有会电离相关较高电离阈值介质的热点 - 高电离阈值介质（如氦气）的基于激光的局部隧道电离 - 传入的计量电子和激光脉冲、等离子体介质和产生的电子脉冲该项目是在欧洲与慕尼黑大学作为主要合作伙伴的合作中实现的。 [1] Hidding, B. ... Karsch, S. 等人，混合激光等离子体韦克场加速器中的单能能量倍增，物理学。莱特牧师。 104, 195002 (2010)[2] 直接观察激光加速电子束引起的等离子体波和动力学，M. F. Gilljohann .. B. Hidding .. S. Karsch, 物理评论 X 9, 011046 (2019)[3] T Kurz, T. Heinemann 等人，由激光加速电子驱动的紧凑型等离子体加速器的演示梁，arXiv：1909.06676[4] G.G. Manahan .. Hidding, B.，用于超高 6D 亮度电子束的基于单级等离子体的相关能量扩散补偿，Nat。 Communications 8, 15705 (2017)[5] A. Deng .. Hidding, B.，等离子体光电阴极产生电子束，Nat。物理（2019）