[25p-D316-1~14] 3.6 超高速・高強度レーザー

▲ [25p-D316-10] BISER enhancement with Astra laser

Alexey Shatokhin¹、Alexander Kotov²、Tae Moon Jeong³、Gabriele Maria Grittani³、Thomas Dzelzainis⁴、Gregory Hull⁴、Stephen Dann⁴、Akito Sagisaka⁵、Eugene Vishnyakov¹、Alexey Kolesnikov¹、Masato Koike⁵、Timur Esirkepov⁵、Masaki Kando⁵、Koichi Ogura⁵、Tatiana Pikuz⁶、James K. Koga⁵、Hiromitsu Kiriyama⁵、Alexander Soloviev²、Eugene Ragozin¹、Sergei Bulanov³、Kiminori Kondo⁵、Tetsuya Kawachi⁵、Dan Symes⁴、David Neely⁴、〇Alexander Pirozhkov⁵ (1.LPI RAS、2.IAP RAS、3.ELI-BL、4.CLF RAL、5.QST、6.Osaka Univ.)

キーワード：Burst Intensification by Singularity Emitting Radiation (BISER), Bright coherent x-rays, High-power femtosecond lasers

Burst Intensification by Singularity Emitting Radiation (BISER) is the phenomenon of extremely bright coherent wave emission (constructive interference, N² effect) by singularities of multi-stream flows. High-power femtosecond lasers can produce such flows and corresponding relativistic plasma singularities in underdense plasma; these singularities emit very bright coherent x-rays. We have recently performed an experiment on BISER coherent x-ray generation with the Astra Laser in the CLF RAL, UK. We observed BISER coherent soft x-rays with two spectrographs: a three-channel flat field spectrograph in the forward direction (channels at -0.6, 0, and 0.8°) operating in the 17-34 nm range and a normal-incidence imaging spectrograph in a 10° off-axis direction operating in the 12.4-20 nm range. Both spectrographs, in addition, provided data on the angular distribution of the BISER radiation. We took advantage of an extensive experiment term and long daily laser operation hours to optimize the laser (in particular, focal spot, which is a necessary prerequisite for BISER, and pulse width) and the experimental conditions (in particular, the plasma density profile). Compared to earlier experiments with similar laser power (~10 TW), these resulted in ~2 orders of magnitude enhancement in BISER photon number, providing >10¹¹ photons and >μJ energies per pulse in each channel at 7 TW. Such result could previously be obtained at >100 TW laser power only.

We acknowledge support from the Astra Laser Group and the CLF Target Fab, Mechanical, and Electrical. Financial support: JSPS Kakenhi JP 19KK0355 and 19H00669, CLF, Russian Science Foundation (20-62-46050), IAP RAS, ELI-Beamlines, the Ministry of Education, Youth and Sports of the Czech Republic by the project "Advanced Research Using High Intensity Laser Produced Photons and Particles" (CZ.02.1.01/0.0/0.0/16_019/0000789), and the QST Director Fund #20.