Time resolved and time integrated analysis of the AXUV photodiode diagnostics for EUV and soft X-ray emission of nanosecond-laser-produced plasma

• Published in: Fusion engineering and design 2020-07, Vol.156, p.111589, Article 111589
• Main Authors: Farahbod, A.H., Morshedian, N., Aram, M.
• Format: Article
• Language: English
• Subjects: AXUV photodiode; Emission analysis; Energy conversion efficiency; EUV and soft X-ray; Free-bond transition; Free-free transition; Laser induced plasma; Lasers; Photodiodes; Soft x rays
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2020.111589

A visual summary of an article’s main findings are: 1) The EUV and SX signals with three specific peaks are detected by AXUV photodiode. From the analysis of time resolved of the AXUV signal, it is inferred that the first and main signal peak can dominantly be related to the free-free transition mechanism of radiation which is comparable to the theoretical results. 2) Also the latter physical signals-peaks with appropriate time-delay can be related to the free-band and bond-bond transitions respectively. 3) The energy of EUV and SX pulse emission is observed to be approximately linear, proportional to the laser pulse energy. 4) The time integrated results show that, the very low average energy conversion efficiency is mainly due to the ambient gas pressure and the angle of detection directions relative to the normal surface of the target. [Display omitted] This paper addresses the experimental results and analysis of the time-resolved and time-integrated of AXUV (absolute extreme ultraviolet) photodiode diagnostics. These results are obtained by the measurement of EUV and soft X-ray (SX) power radiation of plasma-produced under the interaction of laser pulse (intensity ∼5 × 1011 W/cm2, pulse durations in the range of 10−30 ns and wavelength 1064 nm) with one steel-316 target. The EUV and SX signals with the three specific peaks are detected by AXUV photodiode. From the analysis of time resolved of the AXUV signal, it is inferred that the first signal peak can dominantly be related to the free-free transition mechanism of radiation and also the latter related to the free-band and bond-bond transitions respectively. The energy of EUV and SX pulse emission is observed to be approximately linear, proportional to the laser pulse energy. The time integrated results show that, the average energy conversion efficiency is determined to be about 3.7 %.