Bochkarev S G, Faenov A, Pikuz T, Brantov A V, Kovalev V F, Skobelev I, Pikuz S, Kodama R, Popov K I, Bychenkov V Yu
P.N. Lebedev Physical Institute, RAS, Moscow, 119333, Russia.
Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Osaka, 565-0871, Japan.
Sci Rep. 2018 Jun 20;8(1):9404. doi: 10.1038/s41598-018-27665-x.
The use of gas cluster media as a target for an intense femtosecond laser pulses is considered to be uniquely convenient approach for the development of a compact versatile pulsed source of ionizing radiation. Also, one may consider cluster media as a nanolab to investigate fundamental issues of intense optical fields interaction with sub-wavelength scale structures. However, conventional diagnostic methods fail to register highly charged ion states from a cluster plasma because of strong recombination in the ambient gas. In the paper we introduce high-resolution X-ray spectroscopy method allowing to study energy spectra of highly charged ions created in the area of most intense laser radiation. The emission of CO clusters were analyzed in experiments with 60 fs 780 nm laser pulses of 10 W/cm intensity. Theory and according X-ray spectra modeling allows to reveal the energy spectra and yield of highly charged oxygen ions. It was found that while the laser of fundamental frequency creates commonly expected monotonic ion energy spectrum, frequency doubled laser radiation initiates energy spectra featuring of distinctive quasi-monoenergetic peaks. The later would provide definite advantage in further development of laser-plasma based compact ion accelerators.
将气体团簇介质用作强飞秒激光脉冲的靶标，被认为是开发紧凑型通用脉冲电离辐射源的独特便利方法。此外，人们可以将团簇介质视为一个纳米实验室，用于研究强光学场与亚波长尺度结构相互作用的基本问题。然而，由于周围气体中的强复合作用，传统诊断方法无法记录来自团簇等离子体的高电荷离子态。在本文中，我们介绍了一种高分辨率X射线光谱方法，该方法能够研究在最强激光辐射区域产生的高电荷离子的能谱。在强度为10 W/cm²的60 fs 780 nm激光脉冲实验中，对CO团簇的发射进行了分析。理论和相应的X射线光谱建模能够揭示高电荷氧离子的能谱和产额。结果发现，基频激光产生的是通常预期的单调离子能谱，而倍频激光辐射引发的能谱具有独特的准单能峰特征。这将为基于激光等离子体的紧凑型离子加速器的进一步发展提供明确优势。
