Showing papers by "Princeton Plasma Physics Laboratory published in 1978"
TL;DR: In this paper, the surface conditions of the PLT vacuum vessel wall have been monitored by periodic analysis of a variety of sample substrates (stainless steel, alumina, silicon, and silicon) exposed to PLT discharges for periods of up to several months and subsequently removed for analysis by Auger electron spectroscopy (AES), photoelectron spectrography (ESCA), ion backscattering, nuclear reaction analysis, secondary ion mass spectrometry (SIMS), and scanning electron microscopy.
56 citations
TL;DR: In this paper, it was pointed out that the accidentally resonant charge exchange reaction, O/sup +/ + H/sup 0/ reverse arrows, is an important mechanism for causing the loss of singly charged oxygen ions from oxygen contaminated hydrogen plasmas.
Abstract: It is pointed out that the accidentally resonant charge exchange reaction, O/sup +/ + H/sup 0/ reverse arrows O/sup 0/ + H/sup +/, is an important mechanism for causing the loss of singly charged oxygen ions from oxygen contaminated hydrogen plasmas. Results of a Monte Carlo simulation are presented which show that the fraction of oxygen lost because of charge exchange exceeds /sup 1///sub 3/ when the parameters n/sub e/ approx. 10/sup 13/cm/sup -3/, n/sub H//sup o/ approx. 10/sup 11/cm/sup -3/ and T/sub e/ approx. 3 eV are attained.
23 citations
TL;DR: The results of helium implantation during sputtering of stainless steel are described in this paper, where the authors simulate the simultaneous bombardment of unconfined 3.5 MeV alpha particles and erosion due to sputtering primarily from the charge exchange neutral flux.
13 citations
TL;DR: In this article, an asymptotic expansion for the electrostatic potential in cold plasma due to excitation near the lower hybrid frequency is developed which is valid in the presence of two-dimensional field and density inhomogeneities.
Abstract: An asymptotic expansion for the electrostatic potential in cold plasma due to excitation near the lower-hybrid frequency is developed which is valid in the presence of two-dimensional field and density inhomogeneities. The lowest-order terms of the expansion yield the resonance cone surfaces and WKB amplification factors associated with finite-sized sources. The technique is applied to investigate phased waveguide array excitation.
9 citations
01 Dec 1978
TL;DR: The particle flux and angular distribution of 3.5 MeV alpha particles impinging on the first wall from uncontained banana orbits in an axisymmetric tokamak reactor have been calculated in this article.
Abstract: The particle flux and angular distribution of 3.5 MeV alpha particles impinging on the first wall from uncontained banana orbits in an axisymmetric tokamak reactor have been calculated. The resulting helium concentration profiles in the first wall can give rise to surface exfoliation under specified conditions. The major mitigating factor is the simultaneous surface recession due to sputtering by the D-T charge-exchange neutral flux. For the parameters used in these calculations blistering in high-sputtering-rate materials such as beryllium is unlikely, whereas in low-sputtering-rate materials such as niobium helium-induced surface deformation is quite probable.
2 citations
01 Jan 1978
TL;DR: In this paper, the properties of deuterium plasmas in experimental tokamaks heated and fueled by intense neutral-beam injection are evaluated with a Fokker-Planck/radial transport code coupled with a Monte Carlo neutrals treatment.
Abstract: The properties of deuterium plasmas in experimental tokamaks heated and fueled by intense neutral-beam injection are evaluated with a Fokker-Planck/radial transport code coupled with a Monte Carlo neutrals treatment. Illustrative results are presented for the Poloidal Divertor Experiment at PPPL as a function of beam power and plasma recycling coefficient, R/sub c/. When P/sub beam/ = 8 MW at E/sub b/ = 60 keV, and R/sub c/ = 0.2, then approximately 0.5, (/sup 2///sub 3/ ) = 22 keV approximately 6, and the D-D neutron intensity is 10/sup 16/ n/sec.
2 citations
1 citations
01 Apr 1978
TL;DR: In this paper, neutral-beam heating and current induction have been analyzed with a one-dimensional model that includes a Fokker-Planck analysis of the circulating ion current, the time and space dependence of the electron ''return'' current, and the steady electron shielding current including electron trapping effects.
Abstract: Neutral-beam heating and current induction have been analyzed with a one-dimensional model that includes a Fokker-Planck analysis of the circulating ion current, the time and space dependence of the electron ''return'' current, and the steady electron shielding current including electron trapping effects. With 1.2 MW of 40 keV H/sup 0/ injected tangentially into a 25-cm radius PLT plasma with = 2.0 x 10/sup 13/ cm/sup -3/, the maximum beam-driven current is about 100 kA and results in a 0.24-V reduction in loop voltage. Reversed loop voltages should be observable in low density plasmas in ISX-B and TFTR, which would provide an unambiguous detection of the beam-driven current. When the radial profiles of beam-driven current are less peaked than the ohmic-current profile, the profiles of the ''safety factor'' q should be more stable to n = 1, m = 1 and n = 1, m = 2 kink modes, if the total plasma current is kept constant.