Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis

The distribution of solar-wind ions in Genesis mission collectors, as determined by depth profiling analysis, constrains the physics of ion-solid interactions involving the solar wind. Thus, they provide an experimental basis for revealing ancient solar activities represented by solar-wind implants in natural samples. We measured the first depth profile of ^4He in a Genesis collector; the shallow implantation (peaking at <20 nm) required us to use sputtered neutral mass spectrometry with post-photoionization by a strong field. The solar wind He fluence calculated using depth profiling is ~8.5 × 10^(14) cm^(–2). The shape of the solar wind 4He depth profile is consistent with TRIM simulations using the observed ^4He velocity distribution during the Genesis mission. It is therefore likely that all solar-wind elements heavier than H are completely intact in this Genesis collector and, consequently, the solar particle energy distributions for each element can be calculated from their depth profiles. Ancient solar activities and space weathering of solar system objects could be quantitatively reproduced by solar particle implantation profiles

Measurements of electron temperature and density of a micro-discharge plasma using laser Thomson scattering

Laser Thomson scattering was successfully applied to measure electron temperature (T-e) and electron density (n(e)) in a micro-discharge plasma. This is the first time that this method has been used to obtain otherwise inaccessible plasma information from the near vicinity (0.3 mm) of a material surface. The key of the success was the suppression of strong stray laser light by using a triple-grating spectrometer. Values of electron temperature and density were T-e = (0.4-1.6) eV and n(e) = (6-10) x 10(18) m(-3), depending on the time from the beginning of the pulsed discharge. The technique developed here is readily applicable to plasma display panel (PDP) discharges

Two-dimensional simulations of multi-hollow VHF SiH4/H2 plasma

A triode multi-hollow VHF SiH4/H2 plasma (60 MHz) was examined at a pressure of 20 Pa by two-dimensional simulations using the fluid model. In this study, we considered the effect of the rate constant of reaction, SiH3 + SiH3→SiH2 + SiH4, on the plasma characteristics. A typical VHF plasma of a high-electron density with a low-electron temperature was obtained between two discharge electrodes. Spatial profiles of SiH3+, SiH2+, SiH3- and SiH3 densities were similar to that of the electron density while the electron temperature had a maximum value near the two discharge electrodes. It was found that the SiH3 radical density did not decrease rapidly near the substrate and the electron temperature was lower than 1 eV, suggesting that the triode multi-hollow plasma source can provide high quality amorphous silicon with a high deposition rate

Aberration-corrected focused ion beam for time-of-flight secondary neutral mass spectrometry

A chromatic and spherical aberration corrector with liquid Ga ion metal source was developed. The aberration corrector reduced the ion probe diameter to similar to 1.5 times smaller for the Ga-69(+) beam in aberration correction mode compared with the corrector in non-aberration correction mode. The probe current at a given probe size is approximately two times larger in aberration correction mode than in non-aberration correction mode. The aberration-corrected focused ion beam yields higher lateral resolutions and higher sensitivities with lower acceleration voltage for the same acquisition time down to 10 nm with a current of 1 pA. (C) 2019 The Japan Society of Applied Physic

Investigation of VHF Argon Plasma at High Pressure by Balanced Power Feeding Using Laser Thomson Scattering

The dependences of the VHF plasma parameters on the gas pressure and power were examined by using the Laser Thomson scattering method, where the VHF plasma was produced in the high pressure region by the balanced power feeding method. It was found that the balanced power feeding method provides a high electron density plasma with low electron temperature at high pressures. This characteristics were confirmed by calculations using a 2-dimensional simulation code