Low electron temperature in ablating materials formed by picosecond soft X-ray laser pulses

Ishino, Masahiko; Hasegawa, Noboru; Nishikino, Masaharu; Pikuz, T.*; Skobelev, I. Y.*; Faenov, A.*; Inogamov, N.*; Kawachi, Tetsuya; Yamagiwa, Mitsuru

X-Ray Lasers and Coherent X-Ray Sources; Development and Applications XI (Proceedings of SPIE, Vol.9589), p.958904_1 - 958904_6, 2015/09

https://doi.org/10.1117/12.2186053

To study the ablation process induced by the soft X-ray laser pulse, we investigated the electron temperature of the ablating material. Focused soft X-ray laser pulses having a wavelength of 13.9 nm and duration of 7 ps were irradiated onto target surfaces, and we observed the optical emission from surfaces by use of an optical camera. On target surfaces, we could confirm damage structures, but no emission signal in the visible spectral range during ablation could be observed. Then, we estimated the electron temperature in the ablating matter, and we estimated the electron temperature to be lower than 1 eV and the process duration was shorter than 1000 ps. This result is in good accordance with the theoretical prediction. Our investigation implies that the spallative ablation occurs in the low electron temperature region of a non-equilibrium state of warm dense matter. We will present the current state of our eperimental results.

Very low electron temperature in warm dense matter formed by focused picosecond soft X-ray laser pulses

Ishino, Masahiko; Hasegawa, Noboru; Nishikino, Masaharu; Pikuz, T. A.*; Skobelev, I. Y.*; Faenov, A.*; Inogamov, N. A.*; Kawachi, Tetsuya; Yamagiwa, Mitsuru

Journal of Applied Physics, 116(18), p.183302_1 - 183302_6, 2014/11

https://doi.org/10.1063/1.4901943

We investigated the optical emission from the ablating surfaces induced by the irradiations of soft X-ray laser (SXRL) pulses with the aim of estimation of the maximum electron temperature. No emission signal in the spectral range of 400-800 nm could be observed despite the formation of damage structures on the target surfaces. Hence, we estimated an upper limit for the electron temperature of 0.4-0.7 eV for the process duration of 100-1000 ps. Our results imply that the ablation and/or surface modification by the SXRL is not accompanied by plasma formation but is induced by thermo-mechanical pressure, which is so called a spallative ablation. This spallative ablation process occurs in the low electron temperature region of a non-equilibrium state of warm dense matter.

Diagnostics of the early stage of the heating of clusters by a femtosecond laser pulse from the spectra of hollow ions

Faenov, A. Ya.*; Skobelev, I. Yu.*; Pikuz, T. A.; Fortov, V. E.*; Boldarev, A. S.*; Gasilov, V. A.*; Chen, L. M.*; Zhang, L.*; Yan, W. C.*; Yuan, D. W.*; et al.

JETP Letters, 94(3), p.171 - 176, 2011/10

https://doi.org/10.1134/S0021364011150033

Two-temperature warm dense matter produced by ultrashort Extreme Vacuum Ultraviolet-Free Electron Laser (EUV-FEL) pulse

Inogamov, N. A.*; Faenov, A. Ya.*; Zhakhovsky, V. V.*; Pikuz, T. A.*; Skobelev, I. Yu.*; Petrov, Y. V.*; Khokhlov, V. A.*; Shepelev, V. V.*; Anisimov, S. I.*; Fortov, V. E.*; et al.

Contributions to Plasma Physics, 51(5), p.419 - 426, 2011/06

https://doi.org/10.1002/ctpp.201110013

Warm dense matter, arising under the action of ultrashort EUV-FEL pulse onto LiF dielectric crystal, is characterized by high temperature of conduction electrons, with their number density achieving values of the order of atom number density at maximum laser fluences in our experiments. Expansion of matter, heated and pressurized through the electron-ion energy exchange, gives rise to the spallative ablation at small fluences and gaseous outflow from a target in the case of large fluences. Ablation threshold is low in comparison with a longer nanosecond XRL.

Spallative ablation of dielectrics by X-ray laser

Inogamov, N. A.*; Zhakhovsky, V. V.*; Faenov, A. Ya.*; Khokhlov, V. A.*; Shepelev, V. V.*; Skobelev, I. Y.*; Kato, Yoshiaki*; Tanaka, Momoko; Pikuz, T. A.*; Kishimoto, Maki; et al.

Applied Physics A, 101(1), p.87 - 96, 2010/10

https://doi.org/10.1007/s00339-010-5764-3

Metrology of wide field of view nano-thickness foils' homogeneity by conventional and phase contrast soft X-ray imaging

Faenov, A. Y.; Pikuz, T.*; Fukuda, Yuji; Kando, Masaki; Kotaki, Hideyuki; Homma, Takayuki; Kawase, Keigo; Skobelev, I.*; Gasilov, S.*; Kawachi, Tetsuya; et al.

Japanese Journal of Applied Physics, 49(6), p.06GK03_1 - 06GK03_5, 2010/06

https://doi.org/10.1143/JJAP.49.06GK03

Nonequilibrium nonideal nanoplasma generated by a fast single ion in condensed matter

Faenov, A. Y.; Lankin, A. V.*; Morozov, I. V.*; Norman, G. E.*; Pikuz, S. A. Jr.*; Skobelev, I. Yu.*

Plasma Physics and Controlled Fusion, 51(12), p.124025_1 - 124025_8, 2009/11

https://doi.org/10.1088/0741-3335/51/12/124025

Conventional and propagation-based phase contrast imaging of nanostructures using femtosecond laser driven cluster plasma source and LiF crystal soft X-ray detectors

Gasilov, S.*; Faenov, A. Y.; Pikuz, T.*; Skobelev, I.*; Boldarev, A.*; Gasilov, V.*; Magunov, A.*; Fukuda, Yuji; Kando, Masaki; Kotaki, Hideyuki; et al.

Contributions to Plasma Physics, 49(7-8), p.488 - 495, 2009/09

https://doi.org/10.1002/ctpp.200910048

Observation and modelling of hollow multicharged ion X-ray spectra radiated by laser produced plasma

Faenov, A. Y.; Pikuz, T. A.; Skobelev, I. Yu.*; Fukuda, Yuji; Colgan, J.*; Abdallah, J. Jr.*

Journal of Physics; Conference Series, 163(1), p.012016_1 - 012016_4, 2009/06

https://doi.org/10.1088/1742-6596/163/1/012016

MUTA calculations of a laser-produced Mg hollow atom spectrum

Colgan, J.*; Abdallah, J. Jr.*; Faenov, A. Y.; Pikuz, T. A.*; Skobelev, I. Yu.*

Physica Scripta, 78(1), p.015302_1 - 015302_6, 2008/07

https://doi.org/10.1088/0031-8949/78/01/015302