Yoshinobu Matsuda

Energy Dependence of Angular Distributions of Sputtered Particles by Ion-Beam Bombardment at Normal Incidence

The angular distributions of sputtered Fe-atoms were measured using the laser fluorescence technique during Ar-ion bombardment for energies of 0.6, 1, 2 and 3 keV at normal incidence. The measured cosine distribution at 0.6 keV progressively deviated to an over-cosine distribution at higher energies, and at 3 keV the angular distribution was an over-cosine distribution of about 20%. The experimental results agree qualitatively with calculations by a recent computer simulation code, ACAT. The results are explained by the competition between surface scattering and the effects of primary knock-on atoms, which tend to make the angular distributions over-cosine and under-cosine, respectively.

Transient Change in the Velocity Distribution Functions of Sputtered Atoms during Initial Dose in Ion-Beam Bombardment

Velocity distribution functions of sputtered iron-atoms under argon-ion bombardment were directly measured with a rapid-frequency-scan dye laser. Each measured profile was fitted with the Thompson formula, and an equivalent surface binding energy was estimated at each ion dose. The surface binding energy thus obtained was near the formation energy of iron in iron oxides at a low ion dose (less than 1×1019 ions/m2), but approached the sublimation energy of a pure iron above 5×1019 ions/m2.

Ruby-Laser Scattering Diagnostics of a Supersonic Plasma Flow for Low-Pressure Plasma Spraying

Truly reliable measurements of electron temperature and density in a plasma flow for low-pressure plasma spraying (LPPS) were performed for the first time, using incoherent Thomson scattering of ruby-laser light. The results indicate the characteristic feature of a supersonic nozzle flow, namely, successive appearance of oblique shock-wave heating (~1 eV) and compression (4×1021 m-3), and subsequent cooling (~0.2 eV) and rarefaction (1×1021 m-3).

Developments and applications of laser-fluorescence for studies of particle-behaviours in plasma-surface interactions

Abstract The paper is concerned with systematic developments of laser-fluorescence systems for studies of particle-behaviours in plasma-surf ace interactions, namely from (i) appropriate laser developments needed for the fluorescence studies, and (ii) benchmark experiments to check the plausibilities of the techniques, to (iii) applications in measurements on high-temperature plasmas.

VELOCITY-DISTRIBUTION FUNCTIONS OF SPUTTERED ATOMS CAUSED BY INSUFFICIENTLY DEVELOPED COLLISION-CASCADES.

Velocity-distribution functions of sputtered iron atoms by argon-ion bombardment at oblique incidence, measured by laser fluorescence spectroscopy, were found to deviate from the Thompson formula at forward ejection angles relative to the incident ions. The effect was identified as being due to, and quantitatively evaluated by, contributions from insufficiently developed collision-cascades.

Detailed measurements of differential sputtering yields by ion-beam bombardment using laser fluorescence spectroscopy

Abstract Differential sputtering yields caused by argon-ion beam bombardment of iron and titanium targets were measured using laser fluorescence spectroscopy, involving a broad-band dye laser and a narrow-band fast-frequency-scan dye laser. Departures of the yields from the Thompson-Sigmund formalism were found which are attributed to the contribution from unsufficiently developed collision-cascades

Measurement of differential sputtering yields by laser fluorescence spectroscopy

Abstract The technique of laser fluorescence spectroscopy (LFS) was exploited for the study of surface phenomena during ion-beam bombardment by observing the transient change of the velocity distribution functions from pure iron and iron-oxide targets. It was shown that the surface binding energy of compound as well as pure materials could thus be measured. In addition, the LFS technique was expanded to the VUV region by observing the fluorescence signal of carbon atoms sputtered from a graphite target.

Measurement of Preferential Sputtering of Iron-Oxides Using Laser Fluorescence Spectroscopy

Laser fluorescence spectroscopy was used to obtain the velocity-distribution function of sputtered iron from iron oxides, and the fitting of the obtained profiles with the Thompson formula yielded the preferential sputtering of oxygen from iron oxides quantitatively.

In-Situ Measurement of Sputtering Yield of Graphite by VUV Laser Fluorescence Spectroscopy

The sputtering yield of graphite was measured for the first time by laser fluorescence spectroscopy using a tunable VUV source, where the optical system was absolutely calibrated by the Rayleigh scattering. It was shown that the technique was useful for quantitative studies of sputtering processes.