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Shrestha, I.

Publications and source records attributed to Shrestha, I..

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Influence of hot electrons on the spectra of iron plasma irradiated by femtosecond laser pulses with 10 21 W/cm 2 intensities

Abstract The use of laboratory experiments as plasma creating sources is a valuable tool for understanding astrophysical observations. Recently plasma created through irradiation by lasers with relativistic intensities has been used to study effects of hot electrons and X-ray pumping on X-ray formation of multiply charged ions spectra. This paper discusses the formation of K -shell Fe spectra recorded from a plasma irradiated by 35 fs pulses with intensities of 10 21 W/cm 2 . Modeling of the spectra suggests three different regions of plasma radiation including a cold ~10 eV region, a mild ~700 eV region, and a hot ~3500 eV region. The influence of hot electrons and X-ray pumping is discussed and a comparison with K -shell Fe spectra from a 1 MA X-pinch experiment is included to highlight the differences due to the shorter time frame of the laser–plasma interaction experiment.

Physics↗
DOE OSTI2014

Mid-Atomic-Number Cylindrical Wire Array Precursor Plasma Studies on Zebra

The precursor plasmas from low wire number cylindrical wire arrays (CWAs) were previously shown to radiate at temperatures >300 eV for Ni-60 (94% Cu and 6% Ni) wires in experiments on the 1-MA Zebra generator. Continued research into precursor plasmas has studied additional midatomic-number materials including Cu and Alumel (95% Ni, 2% Al, 2% Mn, and 1% Si) to determine if the >300 eV temperatures are common for midatomic-number materials. Additionally, current scaling effects were observed by performing CWA precursor experiments at an increased current of 1.5 MA using a load current multiplier. Our results show an increase in a linear radiation yield of ~50% (16 versus 10 kJ/cm) for the experiments at increased current. However, plasma conditions inferred through the modeling of X-ray time-gated spectra are very similar for the precursor plasma in both current conditions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗