Behaviors of Absolute Densities of N, H, and NH₃ at Remote Region of High-Density Radical Source Employing N₂–H₂ Mixture Plasmas

Abstract

Parameters have been specified for electron beams with energies 5-45 MeV from a Brown Boveri betatron for use in computerised dosimetry calculations. A semi-empirical equation is given for the dose a t any point at various depths in water. This equation is a modification to Kawachi's predictive model which was based on solutions of a general age-diffusion equation. The depth doses and isodose curves are predicted as a function of the practical range, source skin distance (SSD) and field size. Depth dose accuracy requirements of f 2y0 above 50% depth dose and +_5% at lower doses, relative to maximum dose, have been set and achieved. Also, the shape of the isodose curves with the constrictions at higher doses and bulging a t lower values are accurately predicted. Computer calculated beams have been used to generate summed isodose distributions for certain clinical situations.

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

“…In summary, the relatively high ammonia fraction of several percent was proven for a broad variation of plasma conditions. Chen et al 32 examined an inductively coupled plasma at 1 Pa and 400 W rf power. They measured the NH 3 density with a quadrupole mass spectrometer for plasma conditions comparable with the present study.…”

“…Jang and Lee 29 previously examined a few aspects in an inductively coupled H 2 -N 2 plasma by measuring n e , T e and ion signal intensities. In addition, there exists a variety of studies about H 2 -N 2 plasmas in which the densities of background gas species 13,20,[30][31][32][33] , radicals 7,8,20,32,34 , electrons 34,35 and ion signals 7,36 as well as the surface loss probability of H and N (see Ref. 7 ) were reported.…”

Plasma-Induced Damage of GaN and Its Recovery by Atomic Hydrogens at a Room Temperature

“…Subsequently the H* radical anneal at a room temperature was carried out in next chamber equipped with the source of high-density hydrogen atoms, namely the high-density radical source (HDRS). Details of this source have been published elsewhere [4].…”

Photoluminescence recovery by in-situ exposure of plasma-damaged n-GaN to atomic hydrogen at room temperature

“…The radical exposure chamber is equipped with a high-density radical source, which has been developed by our group, with a radical density one order of magnitude higher than those of conventional sources. 20 The absolute density of ground state H radicals at the sample position was measured by vacuum ultraviolet absorption spectroscopy. 21 Although both ground-and excited-state H radicals irradiate the sample, we consider that the H radicals in the ground-state are the most effective species in the reaction due to their long lifetime.…”