[21a-S622-1~12] 3.6 超高速・高強度レーザー

▲ [21a-S622-6] High-Order Harmonics from Relativistic Electron Spikes: Statistical Analysis

〇Pirozhkov Alexander S.¹、Esirkepov Timur Zh.¹、Pikuz Tatiana A.²、Faenov Anatoly Ya.²、Ogura Koichi¹、Hayashi Yukio¹、Kotaki Hideyuki¹、Ragozin Eugene N.³、Neely David⁴、Kiriyama Hiromitsu¹、Koga James K.¹、Fukuda Yuji¹、Sagisaka Akito¹、Nishikino Masaharu¹、Imazono Takashi¹、Hasegawa Noboru¹、Kawachi Tetsuya¹、Daido Hiroyuki¹、Kato Yoshiaki⁵、Bulanov Sergei V.¹、Kondo Kiminori¹、Kando Masaki¹ (1.JAEA、2.Osaka Univ.、3.Lebedev Physical Inst.、4.CLF, RAL、5.GPI)

キーワード：Relativistic laser plasma,High-order harmonics,Relativistic electron spikes

High-order harmonics from relativistic electron spikes are generated by multi-terawatt femtosecond lasers focused onto gas jet targets up to irradiances exceeding 10¹⁸ W/cm². Possible applications of these harmonics range from plasma diagnostics to compact bright attosecond x-ray sources. These applications require stability and well understood generation processes. Here we present statistical analysis of the harmonic generation employing a dataset from a large number of shots with the J-KAREN laser with the emphasis on the reproducibility, stability, and spectral shape properties. The latter include analysis of base harmonic frequencies with a typical separation of ~ eV and relatively slow spectral modulations with a period up to a few tens of eV, which may give a hint to the temporal structure of the XUV radiation.

We acknowledge financial support from MEXT, Japan (Kakenhi #25287103, 25390135, and 26707031).