[21a-S622-1~12] 3.6 Ultrashort-pulse and high-intensity lasers

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

〇Alexander S. Pirozhkov¹, Timur Zh. Esirkepov¹, Tatiana A. Pikuz², Anatoly Ya. Faenov², Koichi Ogura¹, Yukio Hayashi¹, Hideyuki Kotaki¹, Eugene N. Ragozin³, David Neely⁴, Hiromitsu Kiriyama¹, James K. Koga¹, Yuji Fukuda¹, Akito Sagisaka¹, Masaharu Nishikino¹, Takashi Imazono¹, Noboru Hasegawa¹, Tetsuya Kawachi¹, Hiroyuki Daido¹, Yoshiaki Kato⁵, Sergei V. Bulanov¹, Kiminori Kondo¹, Masaki Kando¹ (1.JAEA, 2.Osaka Univ., 3.Lebedev Physical Inst., 4.CLF, RAL, 5.GPI)

Keywords: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).