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Electrostatic ion (hydrogen) cyclotron and ion acoustic wave instabilities in regions of upward field-aligned current and upward ion beams
An investigation is made into the stability of electrostatic hydrogen ion cyclotron and ion acoustic waves in a model plasma where an ion beam, population 2, and oppositely directed drifting electrons pass through a stationary ion background, population 1. The excited wave properties are then compared with the characteristics of the unstable modes observed on the S3-3 satellite. Three temperature regimes are studied: (1) Te greater than Ti2 much greater than Ti1, (2) Ti2 greater than Te not less than Ti1, and (3) Te approximately equal to Ti1 greater than Ti2. It is found that the ion beam acts as a free energy source only in regime 1. This regime is also highly unstable to the electrons as a free energy source. Unstable modes in regimes 2 and 3 seem to best satisfy the electrostatic hydrogen cyclotron wave (EHC) properties at 1 earth radius. For these cases the electrons are the free energy source, the beam supplies damping.
Comparison of coincident OGO 3 and OGO 4 hydrogen ion composition measurements
Simultaneous hydrogen ion composition measurements by upper ionospheric polar orbiting OGO 4 and eccentric orbiting magnetospheric OGO 3 at midlatitude
Some deductions from a measurement of the hydrogen ion distribution in the high atmosphere
Hydrogen ion distribution in upper atmosphere
Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells
This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.
A simple correction for the Born approximation for electron impact excitation of hydrogenic ions
An analytic procedure is developed for obtaining the electron impact excitation cross sections for hydrogenic ions. A simple modification of the Born approximation, in order to include Coulomb focusing of the continuum wave functions, produces the correct energy dependence of the cross section near excitation threshold. This procedure is used to compute the 1s yields 2s and 1s yields 2p excitation cross sections for hydrogenic ions (Z approaches infinity), and compare these modified-Born cross sections with numerical Colomb-Born calculations. The modified-Born cross sections agree well with the Coulomb-Born cross sections and thus provide a reliable generalized analytic expression for electron impact excitation of hydrogenic ions. By treating effective charges, the results in this work can be extended to nonhydrogenic target systems.
DIRECT MEASUREMENTS OF HELIUM AND HYDROGEN ION CONCENTRATION AND TOTAL ION DENSITY TO AN ALTITUDE OF 940 KILOMETERS
Helium and hydrogen ions, used to calculate atmospheric temperature, ion mass and ion concentration as functions of altitude
Hydrogen ion velocity distributions in the ionosphere.
Hydrogen ion velocity distributions applied to ionospheric measurements
Two-step process to increase atomic hydrogen ion production in low-pressure radiofrequency discharge
Increased production of atomic hydrogen ion in low pressure radiofrequency discharge by two step process
Surface blistering of metals due to low energy hydrogen ion bombardment.
Surface blistering of metals due to low energy hydrogen ion bombardment, determining solar absorptance change in gold-plated specimens
Dissociative electron recombination and rotational cooling of the deuterated triatomic hydrogen ions H 2 D + and D 2 H +
We have measured the dissociative recombination (DR) of the deuterated triatomic hydrogen ions H 2 D + and D 2 H + as a function of storage time at the Cryogenic Storage Ring (CSR). Both molecular ions were stored for up to 1000 s inside the cryogenic vacuum of the CSR prior to the electron recombination measurements, allowing them to cool to their lowest rotational states. We implement a comprehensive model for all relevant processes to predict the internal state evolution of the ions during storage inside the CSR, employing calculated radiative transition strengths and state-selective rate coefficients for electron collisions. Our DR rate coefficient measurements with deuterated triatomic hydrogen ions in defined quantum states allow for meaningful comparisons with state-of-the-art theoretical calculations, paving the way for a better understanding of the complex DR process for polyatomic molecular ions.
Determination of hydrogen ion concentration, electron density and proton gyrofrequency from the dispersion of proton whistlers
Hydrogen ion concentration, electron density, and proton gyrofrequency near satellites from asymptotic frequency-time profile of proton whistler near proton gyrofrequency
Evidence that Clouds of keV Hydrogen Ion Clusters Bounce Elastically from a Solid Surface
The behavior of hydrogen ion clusters is tested by an inject/hold/extract technique in a Penning-Malmberg trap. The timing pattern of the extraction signals is consistent with the clusters bouncing elastically from a detector several times. The ion clusters behave more like an elastic fluid than a beam of ions.
Semiclassical approximation for electron impact excitation of hydrogenic ions
The threshold behavior of the electron impact excitation cross sections for hydrogenic ions is investigated using the semiclassical approximation with the hyperbolic orbit for the projectile path, rather than the straight line path. The symmetric approximation is applied to modify the ordinary hyperbolic orbit. The modification factor due to the hyperbolic orbit approximation produces the correct energy dependence of the cross section near the excitation threshold. This result is very similar to that of the quantum mechanical case. The semiclassical enhancement factor due to this simple modification corresponds to the Coulomb focusing factor in the Born-Bethe approximation. In the high-energy limit, the semiclassical cross sections approach the Born-Bethe cross sections, with a finite cutoff in the momentum transfer for dipole transitions.
INTERACTION ENERGIES FROM SCATTERING CROSS SECTIONS OF HYDROGEN IONS IN CH SUB 4, CF SUB 4, C SUB 2 H SUB 6, AND C SUB 2 F SUB 6
Interaction energies from scattering cross section of hydrogen ions in methane, carbon tetrafluoride, ethane, and hexafluoroethane
Possible Fault Control of Hydrogen Ion Concentrations Near Schiaparelli Crater, Mars
Epithermal neutron flux maps of the equatorial region near Schiaparelli Crater in Mars eastern hemisphere indicate hydrogen ion concentrations in the shallow subsurface. Published maps of these hydrogen concentrations reveal anomalous linear concentrations of hydrogen with a northeast to southwest trend. The width and trend of these linear anomalies matches the width and trend of the graben between Scylla Scopulus and Charybdis Scopulus further to the south, west of Hellas Basin. These concentrations are believed to indicate locations of subsurface water ice. As such, the flux maps pinpoint locations where quantities of water may intermittently exist today or where liquid water may have pooled in the past. The possibility of life existing on Mars, either in the distant past or at present, depends on the availability of liquid water.
Plasma-screening effects on the electron-impact excitation of hydrogenic ions in dense plasmas
Plasma-screening effects are investigated on electron-impact excitation of hydrogenic ions in dense plasmas. Scaled cross sections Z(exp 4) sigma for 1s yields 2s and 1s yields 2p are obtained for a Debye-Hueckel model of the screened Coulomb interaction. Ground and excited bound wave functions are modified in the screened Coulomb potential (Debye-Hueckel model) using the Ritz variation method. The resulting atomic wave functions and their eigenenergies agree well with the numerical and high-order perturbation theory calculations for the interesting domain of the Debye length not less than 10. The Born approximation is used to describe the continuum states of the projectile electron. Plasma screening effects on the atomic electrons cannot be neglected in the high-density cases. Including these effects, the cross sections are appreciably increased for 1s yields 2s transitions and decreased for 1s yields 2p transitions.
A hollow cathode hydrogen ion source
High current density ion sources have been used to heat plasmas in controlled thermonuclear reaction experiments. High beam currents imply relatively high emission currents from cathodes which have generally taken the form of tungsten filaments. A hydrogen ion source is described which was primarily developed to assess the emission current capability and design requirements for hollow cathodes for application in neutral injection devices. The hydrogen source produced ions by electron bombardment via a single hollow cathode. Source design followed mercury ion thruster technology, using a weak magnetic field to enhance ionization efficiency.