Effects of bunched ion bursts on apparent nonlinear ion acoustic waves
Bunched ion bursts amplitude modulation effects on nonlinear ion acoustic waves in grid plasma system
Ichikawa, Y. H.↗
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Ion-current response of Langmuir probes in the presence of ion-atom collisions
Ion current response of Langmuir probes in presence of ion-atom collisions in weakly ionized argon plasma
Szuszczewicz, E. P.↗
Ion-ion recombination total cross sections - Atomic species
Atomic ion-ion recombination total inelastic cross sections calculation by Landau-Zener method, noting agreement with experiment
Moseley, J.↗
Cathode and ion chamber investigations on a 20-cm diameter hollow cathode ion thruster
Electron bombardment ion thrustor using hollow cathode and two-grid ion accelerating geometry, discussing performance tests
Fitzgerald, D. J.↗
Transient ion cyclotron resonance method for studying ion-molecule collision and charge- transfer rates- N2/plus/ and CH4/plus/
Ion-molecule collision charge transfer and momentum transfer relaxation rates, using ion cyclotron resonance heterodyning method
Dunbar, R. C.↗
Acidity, basicity, and ion-molecule reactions of phosphine in the gas phase by ion cyclotron resonance spectroscopy
Gas phase ion-molecule phosphine reactions in pure and binary mixtures by ion cyclotron resonance spectroscopy, considering acidity and basicity
Beauchamp, J. L.↗
Photodetachment of negative ions using a continuously tunable laser and an ion cyclotron resonance spectrometer
Negative ions photodetachment by continuously tunable laser and ion cyclotron resonance spectrometer
Brauman, J. I.↗
Comprehensive theory for ion cyclotron resonance power absorption - Application to line shapes for reactive and nonreactive ions
Ion cyclotron resonance power absorption theory application to reactive and nonreactive ions line shapes, using Wobschall-Graham-Malone phenomenological equation of motion
Comisarow, M. B.↗
Ion cyclotron resonance power absorption - Collision frequencies for CO2/plus/, N2/plus/, and H3/plus/ ions in their parent gases
Ion cyclotron resonance power absorption, deriving expression for average ion kinetic energy at saturation in steady state limit
Huntress, W. T., Jr.↗
Investigation of intermittent enhancement of ion emission from a tungsten surface using the field-ion microscope.
The blinking effect, or the intermittent enhancement of ion emission, which is observed when a few parts per million neon are added to the imaging gas in a helium-tungsten field-ion microscope, has been investigated. Measurements of the characteristic quantities involved - i.e., blinking rate, voltage limits, etc. - and their variation with temperature, field, and gas pressure, are described.
Weizer, V. G.↗
Ion-ion beam instability in a cylindrical geometry
The ion-ion instability is studied in a cylindrical double-plasma device. Low-frequency cylindrical standing waves are found which are one-dimensional in character with frequency proportional to beam velocity. An approximate dispersion relation for the cylindrical standing waves is derived.
Hershkowitz, N.↗
High performance auxiliary-propulsion ion thruster with ion-machined accelerator grid
An improvement in thruster performance was achieved by reducing the diameter of the accelerator grid holes. The smaller accelerator grid holes resulted in a reduction in neutral mercury atoms escaping the discharge chamber, which in turn enhanced the discharge propellant utilization from approximately 68 percent to 92 percent. The accelerator grids were fabricated by ion machining with an 8-centimeter-diameter thruster, and the screen grid holes individually focused ion beamlets onto the blank accelerator grid. The resulting accelerator grid holes are less than 1.12 millimeters in diameter, while previously used accelerator grids had hole diameters of 1.69 millimeters. The thruster could be operated with the small-hole accelerator grid at neutralizer potential.
Hudson, W. R.↗
A distorted-wave methodology for electron-ion impact excitation - Calculation for two-electron ions
A distorted-wave program is being developed for calculating the excitation of few-electron ions by electron impact. It uses the exchange approximation to represent the exact initial-state wavefunction in the T-matrix expression for the excitation amplitude. The program has been implemented for excitation of the 2/1,3/(S,P) states of two-electron ions. Some of the astrophysical applications of these cross sections as well as the motivation and requirements of the calculational methodology are discussed.
Bhatia, A. K.↗
'Bottleneck' calculation of ion-electron recombination coefficients for lithium-like ions
The ion-electron recombination coefficients for the lithium-like ions C IV, O VI, Ne VIII, Si XII and Ar XVI are computed by the bottleneck method of Byron et al. (1962). In this method, the minimum rate of transitions down the ladder of energy level is taken as the limiting recombination rate, and the particular energy level corresponding to the minimum transition rate is found. The partial collisional radiative recombination coefficient is obtained in terms of the equilibrium population, the rate of collisional de-excitation, the mean radiative transition probability from the bottleneck level and the total transition probability from a level above the bottleneck level to all levels below it. The full collisional-radiative recombination is then obtained by the addition of the values of the radiative recombination coefficient and the three-body recombination coefficient to the ground level. Results of the calculation are shown to be in good agreement with those of Drawin and Emard (1975) for the case of hydrogen. It is also noted that the process of dielectronic recombination, which is not accounted for here, may be significant at lower densities.
Kastner, S. O.↗
Diagnostic system design for the Ion Auxiliary Propulsion System (IAPS). Flight tests of two 8 cm mercury ion
The mechanical, thermal, electrical design and the ground test results of four types of detectors are explained. The DSS is designed to measure the thruster efflux material deposition and S/C potential relative to the local plasma in the vicinity of two 8 cm mercury ion thrusters. The DSS consists of two quartz crystal microbalance (QCM) detectors, one potential probe, nine solar cell arrays, seven ion collectors and two electronic packages.
Hurst, E. B.↗
Endurance test of a 30-CM-diameter engineering model ion thruster. Task 12: Investigation of thin-film erosion monitors for ion thrusters
An investigation of short term measurement techniques for predicting the wearout of ion thrusters resulting from sputter erosion damage is described. The previously established laminar thin film techniques to provide high precision erosion rate data. However, the erosion rates obtained using this technique are generally substantially higher than those obtained during long term endurance tests (by virtue of the as deposited nature of the thin films), so that the results must be interpreted in a relative sense. Absolute measurements can be performed using a new masked substrate arrangement which was developed during this study. This new technique provides a means for estimating the lifetimes of critical discharge chamber components based on direct measurements of sputter erosion depths obtained during short duration (10 hour) tests. The method enables the effects on lifetime of thruster design and operating parameters to be inferred without the investment of the time and capital required to conduct long term (1000 hour) endurance tests. Results obtained using the direct measurement technique are shown to agree with sputter erosion depths calculated for the plasma conditions of the test and also with lifetest results. The direct measurement approach is shown to be applicable to both mercury and argon discharge plasma environments and should be useful in estimating the lifetimes of inert gas and extended performance mercury ion thrusters presently under development.
Beattie, J. R.↗
An ICR study of ion-molecule reactions of PH(n)+ ions
The reactions of PH(n)+ ions (n = 0-3) were examined with a number of neutrals using ion-cyclotron-resonance techniques. The reactions examined have significance for the distribution of phosphorus in interstellar molecules. The results indicate that interstellar molecules containing the P-O bond are likely to be more abundant than those containing the P-H bond.
Thorne, L. R.↗
Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions
The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.
Wilson, J. W.↗