Gene Q. Blantocas

Surface Modification of Narra Wood (Pterocarpus indicus) by Ion Shower Treatment

A gas discharge ion source (GDIS) was used as test facility to produce and study the characteristics of diffused, low-energy hydrogen ion showers. Narra wood samples were then exposed to the showers to investigate topographical effects of ion irradiation. Analysis of beam constituents by mass spectroscopy shows H+ ions to be the dominant species suggesting an essential participatory role for this particular monatomic ion in the surface modification process. Low energy irradiation (600–700 eV) produced hydrophobic surfaces with scanning electron micrographs showing partial closure of surface pores. Whereas, a reversion to hydrophilicity was observed for higher energy irradiation (>900 eV), with surface images showing exterior degradation believed to be the etching effects of the chemically active H+ species. The irradiated samples absorbency was quantified via the wetting model wherein the contact angles time rate equation was numerically solved and fitted onto experimental data. The change rate proportionality constant K with value 0.0015 corresponding to 600 eV beam energy, exhibited the longest moisture absorptive inhibition time of more than 10 min. An increasing value of K indicates increased wetting behavior.

Design and operational characteristics of a cast steel mass spectrometer

A cast steel magnetic sector mass analyzer is developed for studies of hydrogen and helium ion beams generated by a gas discharge compact ion source. The optimum induced magnetic flux density of 3500 G made it possible to scan the whole spectrum of hydrogen and helium ion species. Analysis of beam characteristics shows that the mass spectrometer sensitivity, and resolving power are approximately inversely proportional. The resolution is enhanced at higher pressures and lower current discharges. In contrast, the instrument sensitivity increased at higher current discharges and decreased at higher pressures. Calculations of the ultimate resolving power with reference to analyzer dimensions yield a numerical value of 30. System anomaly in the form of spherical aberrations was also analyzed using the paraxial beam envelope equation. Beam divergence is most significant at high discharge conditions where angular spread reaches an upper limit of 8.6°.

Extraction and profile analysis of hydrogen-like helium ions in a magnetized sheet plasma

The extraction of He+ ions from a magnetized sheet plasma source is reported. Optimum detection and extraction of He+ ions were conducted using an E×B probe as a mass analyzer. The effect of the probe’s extraction potential, its position relative to the center of the core plasma, gas filling pressure, and discharge conditions in the production and extraction of He+ ions were investigated. The He+ ion current density yield of 8 μA/cm2 was optimum at plasma discharge current of 1.5 A within the vicinity of 5–7 cm from the sheet plasma core. Investigations also show the predominance of detected He++ species. At higher pressures, the formation of molecular helium ions He2+ were observed. The He+ current yield decreases as the plasma current is increased according to the modified Saha population density equation of the collisional-radiative model.