Sub-nanometer scale depth patterning on sapphire crystal by femtosecond soft x-ray laser pulse irradiation.

Damage thresholds and structures on a metal aluminum and an aluminum oxide crystal induced by the soft x-ray free electron laser irradiations were evaluated. Distinctive differences in damage thresholds and structures were observed for these materials. On the aluminum oxide crystal surface, in particular, a novel, to the best of our knowledge, surface processing, which we suggest defining as "peeling," was recognized.

Damage threshold of LiF crystal irradiated by femtosecond hard XFEL pulse sequence.

Here we demonstrate the results of investigating the damage threshold of a LiF crystal after irradiating it with a sequence of coherent femtosecond pulses using the European X-ray Free Electron Laser (EuXFEL). The laser fluxes on the crystal surface varied in the range ∼ 0.015-13 kJ/cm per pulse when irradiated with a sequence of 1-100 pulses (t ∼ 20 fs, E = 9 keV).

Independent contribution of optical attenuation length in ultrafast laser-induced structural change.

Although laser irradiation with femtosecond pulses is known to generate crystallization and morphological changes, the contribution of optical parameters to material changes is still in discussion. Here, we compare two structures irradiated near Si-L2,3 edges by an extreme ultraviolet femtosecond pulse. Our result implies that, despite the femtosecond irradiation regime, these values of the optical attenuation length between the wavelengths of 10.

Absolute response of a Fuji BAS-TR imaging plate to low-energy protons (<0.2 MeV) and carbon ions (<1 MeV).

This paper reports on the absolute response of a Fuji BAS-TR image plate to relatively low-energy protons (<0.2 MeV) and carbon ions (<1 MeV) accelerated by a 10-TW-class compact high-intensity laser system. A Thomson parabola spectrometer was used to discriminate between different ion species while dispersing the ions according to their kinetic energy.

Compact Thomson parabola spectrometer with variability of energy range and measurability of angular distribution for low-energy laser-driven accelerated ions.

This article reports the development of a compact Thomson parabola spectrometer for laser-accelerated ions that can measure angular distribution with a high energy resolution and has a variable measurable energy range. The angular-resolved energy spectra for different ion species can be measured in a single shot, and the sampling angle can be selected from outside the vacuum region. The electric and magnetic fields are applied to the ion dispersion by using a permanent magnetic circuit and annulus sector-shaped electrodes with a wedge configuration.

Surface processing of PMMA and metal nano-particle resist by sub-micrometer focusing of coherent extreme ultraviolet high-order harmonics pulses.

We demonstrate sub-micrometer processing of two kinds of thin films, polymethyl methacrylate (PMMA) and metal nano-particle resist, by focusing high-order harmonics of near-IR femtosecond laser pulses in the extreme ultraviolet (XUV) wavelength region (27.2-34.3 nm) on the thin film samples using an ellipsoidal focusing mirror.

Soft x-ray laser beamline for surface processing and damage studies.

We have developed a soft x-ray laser (SXRL) beamline equipped with an intensity monitor dedicated to ablation study such as surface processing and damage formation. The SXRL beam having a wavelength of 13.9 nm, pulse width of 7 ps, and pulse energy of around 200 nJ is generated from Ag plasma mediums using an oscillator-amplifier configuration.

Laser-induced damage thresholds and mechanism of silica glass induced by ultra-short soft x-ray laser pulse irradiation.

Laser-induced damage thresholds (LIDTs) of silica glasses obtained by the femtosecond soft x-ray free-electron laser (SXFEL, 13.5 nm, 70 fs) and the picosecond soft x-ray laser (SXRL, 13.9 nm, 7 ps) are evaluated.

Evaluation of a flat-field grazing incidence spectrometer for highly charged ion plasma emission in soft x-ray spectral region from 1 to 10 nm.

A flat-field grazing incidence spectrometer operating on the spectral region from 1 to 10 nm was built for research on physics of high temperature and high energy density plasmas. It consists of a flat-field grating with 2400 lines/mm as a dispersing element and an x-ray charged coupled device (CCD) camera as the detector. The diffraction efficiency of the grating and the sensitivity of the CCD camera were directly measured by use of synchrotron radiation at the BL-11D beamline of the Photon Factory (PF).

Note: development of a volume-limited dot target for a high brightness extreme ultraviolet microplasma source.

We report on production of volume-limited dot targets based on electron beam lithographic and sputtering technologies for use in efficient high brightness extreme ultraviolet microplasma sources. We successfully produced cylindrical tin (Sn) targets with diameters of 10, 15, and 20 μm and a height of 150 nm. The calculated spectrum around 13.