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Ion-quadrupole effects are investigated via numerical calculations of capture cross sections and computer-plotter studies of ion trajectories in the quadrupole field. Capture cross sections are roughly equal to Langevin values for low rotational temperatures; a large fraction of multiple reflection captures are calculated corresponding to formation of ion-molecule complexes.
A mass spectrometer for the separation or separate indication of ions of different specific electric charges is reported. The instrument uses a periodically varying electric field in its analyzing section to excite the injected ions into oscillations while traveling along their trajectories which are either stable or unstable depending on specific parameters. Only stable trajectory ions pass through the electric field to the collector for indication.
A new detector using an extremelly driven tuned circuit has been developed for use in ion cyclotron resonance spectroscopy experiments. Based on the Q-meter circuit, this detector will operate at frequencies greater than 1 MHz at rf levels less than 1 mV. Operation in the frequency range 1-15 MHz allows the use of higher magnetic fields for more efficient storage of low mass ions in the trapping mode of operation. In the frequency range 2-6 MHz electrons can be detected in the ion cyclotron resonance cell by their resonant motion in the trapping plane.
Product distributions and rate constants for the reaction of ground state C(+) ions with O2, NO, HCl, CO2, H2S, H2O, HCN, NH3, CH4, H2CO, CH3OH, and CH3NH2 have been measured. Rate constants were obtained using ion cyclotron resonance trapped ion methods, and product distributions were obtained using a tandem mass spectrometer. Rapid carbon isotope exchange has also been observed in C(+)-CO collisions.
Product distributions and rate constants for the reactions of ground-state N(+) ions with CO, NO, CO2, and CH4 were measured. Rate constants were obtained using ion-cyclotron-resonance trapped-ion methods, and product distributions were obtained using a tandem (Dempster-ICR) mass spectrometer. Rapid nitrogen isotope exchange was also observed in N(+)-N2 collisions.
S ions with a mean charge state of about 14+ and Cl ions with a mean charge state of 12+ were used to study Ne L-shell vacancy production. The ions caused copious production of NeII-NeVIII excited states with approximately 10 to the minus 18 sq cm cross sections. The induced recoil velocities might have application to a significantly higher resolution spectroscopy than is possible with beam-foil methods.
Reactions of various positive ions with water vapor were studied by ion cyclotron resonance mass spectrometric techniques. Rate constants and product distributions were determined for reactions of the ions: Ar(+), Co(+), N2(+), and CO2(+), CH2(+), and CH4(+), CH2Cl(+), HCO(+), H2CO(+), H2COH(+), H2S(+) and HS(+). The results obtained in this work are compared with earlier reported data where available.
The abundance of He and CNO ions in the ion pulses which are frequently observed in the earth's magnetosheath, magnetotail, and near-by interplanetary space was analyzed and found to be highly variable. Based on the assumption that these ions are solar wind particles accelerated in the magnetospheric environment to the observed energies, it is suggested that this variability reflects the inhomogeneity of the solar atmosphere and/or the physical conditions under which the solar wind particles were energized.
Measurements are reported of the attenuation of an ion beam in a multidipole double-plasma (DP) device. In addition to charge-exchange collisions of the beam ions with the gas atoms, ion scattering by the three-dimensional turbulence produced by the beam itself is found to contribute significantly to the beam attenuation.
Hot-ion plasma experiments were conducted in the NASA Lewis SUMMA facility. A steady-state modified Penning discharge was formed by applying a radially inward dc electric field of several kilovolts near the magnetic mirror maxima. Results are reported for a hydrogen plasma covering a wide range in midplane magnetic flux densities from 0.5 to 3.37 T. Input power greater than 45 kW was obtained with water-cooled cathodes. Steady-state plasmas with ion kinetic temperatures from 18 to 830 eV were produced and measured spectroscopically. These ion temperatures were correlated with current, voltage, and magnetic flux density as the independent variables. Electron density measurements were made using an unusually sensitive Thomson scattering apparatus. The measured electron densities range from 2.1 x 10 to the 11th to 6.8 x 10 to the 12th per cu cm.
A comparative investigation concerning the spatial distribution of ions in the wake of small bodies was conducted using the theoretical wake models of Call (1969) and Parker (1976). Results for bodies with radius/ambient Debye length ratios of 2 and 5, with an electron temperature equal to the ambient electron temperature, and for the ionic Mach numbers S = 2, 4, 6, 8 are presented. Since the main physical difference between the models is in the consideration of the thermal motion of ions (Parker) versus ignoring this component (Call), a comparison between the models yields the quantitative significance of this component in determining the distribution of ions in the wake of artificial satellites. The application of this result to future experiments to be conducted on board the Spacelab and for any other large space platform in the area of space plasma physics is mentioned.
The criterion for the existence of vortex-like ion phase-space configurations, as obtained by a standard pseudopotential method, is found to coincide with the criterion for the linear instability for two (cold) counterstreaming ion beams. A nonlinear equation is derived, which demonstrates that this instability actually evolves into such phase-space configurations. A small, but nonzero, ion temperature turns out to be essential for the saturation into stationary structures
Working fluid utilized efficiently. Working fluid positive ions conducted through solid electrolyte to outside, then accelerated in external electric field. While in solid-electrolyte material, ions do not recombine with electrons: transported to surface with high ionization efficiency. Provides new way to generate beam of ions for implantation in semiconductors or other applications.
Observation of electromagnetic waves in the low-altitude auroral zone at frequencies between the proton and helium gyrofrequencies suggests that Alfven-ion cyclotron waves modified by the presence of helium ions are being excited. Estimates of the growth rates for this mode indicate that the auroral electron beam can provide the free energy for the instability. The effect of the heavy ions is to decrease the group velocity of the waves, leading to larger convective growth. Theoretical wave spectra are computed in the local approximation, which assumes that the gradient scale lengths in density and magnetic field are constant over the ray paths. Narrow banded spectral peaks similar to observations may be produced when the thickness of the electron beam is small (200 m at 3000 km altitude). Narrow beams also limit growth of whistler mode waves, which compete for the free energy of the electron beam.
The thermal and suprathermal ion populations present in the refilling regions after a magnetic storm are examined using retarding ion mass spectrometer (RIMS) data from the Dynamics Explorer 1 spacecraft. The RIMS instrument is described, and data are presented and discussed in detail for the outer plasmasphere, plasmapause, depleted dayside magnetosphere, and dayside cusp. Three distinct populations were observed: thermal ions, warm anisotropic plasma, and the polar wind. The characteristics of these populations are considered, including the densities, temperatures, and density ratios. Aspects of the ionospheric plasma outflow are discussed, including the field-aligned flow speed, the ionospheric plasma escape flux, plasmaspheric refilling, and wave-particle phenomena.
An expression for electromagnetic ion cyclotron convective growth rates is derived. The derivation of the dispersion relation and convective growth rates in the presence of a multicomponent energetic and cold plasma is presented. The effects that multiple heavy ions in the ring current and cold plasma produce in the growth and propagation characteristics of ion cyclotron waves are explored. Results of growth rate calculations using parameters consistent with conditions in the plasmapause region during the early recovery phase of geomagnetic storms are presented and compared with ground-based and satellite observations of waves in this region. The geophysical implications of the results are discussed.
The stability of H(+) and H(++) ring distributions which have been observed downflowing into the cusp on the DE and S3-3 satellites is examined in the context of the feedback of those instabilities on plasma of ionospheric origin consisting of (H(+) and O(+). Lower hybrid waves are excited by the ring distributions in three distinct phases of wave-particle interaction: linear growth, trapping, and quasi-linear diffusion.The latter phase accounts for most particle heating. Including background O(+) and/or a He(++) ring introduces new modes not present in a pure H(+) plasma which play an important role in heating heavier ions. O(+) is heated significantly more by a He(++) ring than a H(+) ring of comparable energy density. It is suggested that lower hybrid waves generated by downflowing ion ring distributions play a role in energizing ion conics in the cusp.
The process used at the NASA-Lewis to fabricate 30 and 50-cm-diameter ion optics is described. The ion extraction capabilities of the 30 and 50-cm diameter ion optics were evaluated on divergent field and ring-cusp discharge chambers and compared. Perveance was found to be sensitive to the effects of the type and power of the discharge chamber and to the accelerator electrode hole diameter. Levels of up to 0.64 N and 20 kW for thrust and input power, respectively, were demonstrated with the divergent-field discharge chamber. Thruster efficiencies and specific impulse values up to 79 percent and 5000 sec., respectively, were achieved with the ring-cusp discharge chamber.