Laser Plasma Soft X‐Ray Source in the Water Window Based on Cryogenic Targets

• Published in: Electronics and communications in Japan Vol. 101; no. 1; pp. 55 - 60
• Main Author: AMANO, SHO
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01-01-2018
• Subjects: argon; cryogenic target; Emission analysis; high average power; Lasers; laser‐plasma X‐ray; nitrogen; Nitrogen plasma; Plasmas (physics); Soft x rays; Spectral emissivity; Substrates; water window; X ray microscopy; X ray sources; X-rays; YAG lasers
• ISSN: 1942-9533; 1942-9541
• DOI: 10.1002/ecj.12022

SUMMARY
To generate continuously repetitive soft X‐ray pulses in the water window from laser‐produced plasmas, a one‐dimensionally translating substrate system with a closed He gas cryostat that can continuously supply various cryogenic targets has been developed. The system was successfully operated at a lowest temperature of 15 K and at a maximum up‐down speed of 12 mm/s. Solid Ar and N2 layers were formed, and the water‐window spectra from them were studied. The emission intensity from Ar was found to be about eight times stronger than that from N2. Developed laser‐plasma source demonstrated high average power of 140 mW in the water‐window soft X‐ray, when a commercial Nd:YAG Q‐switched laser was used to irradiate a solid Ar target with energy of 1 J at a repetition rate of 1 Hz. It can be used for various applications, including soft X‐ray microscopy, in place of synchrotron facilities.