Mass and phase spectrometry in modulated beam experiments
Mass and phase spectrometry in modulated molecular beam experiment for neutral particles velocity measurement prior to ionization
Fite, W. L.↗
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Thermospheric temperature and density variations with increasing solar activity
Thermospheric neutral particle molecular nitrogen density and temperature measurements by rockets, noting correlations with diurnal, solar cycle and other variations
Carignan, G. R.↗
6-centimeter formaldehyde absorption and emission in the Orion Nebula
Formaldehyde absorption and emission lines in Orion IR nebula, indicating pumping suppression by neutral particle collisions
Kutner, M.↗
The application of the phase space time evolution method to electron shielding
A computer technique for treating the motion of charged and neutral particles and called the phase space time evolution method was developed. This technique employs the computer's bookkeeping capacity to keep track of the time development of a phase space distribution of particles. This method was applied to a study of the penetration of electrons. A 1 MeV beam of electrons normally incident on a semi-infinite slab of aluminum was used. Results of the calculation were compared with Monte Carlo calculations and experimental results. Time-dependent PSTE electron penetration results for the same problem are presented.
Cordaro, M. C.↗
Steady-state hot-ion plasma produced by crossed electric and magnetic fields
Results of initial diagnostics on the Lewis Research Center hot-ion-plasma source (HIP-1) are reported. The mirror-contained plasma was heated by applying a radial electric field similar to that used in the ORNL burnout experiments. An electrostatic neutral particle analyzer was used to make a parametric study of ion energy distributions in both hydrogen and euterium plasmas. Ion temperatures as high as 2 keV were measured in plasmas with electron densities greater than 10 to 12th power/cu cm. The performance of the device was found to be extremely sensitive to a magnetic field. There are indications that ion heating was reduced when the size of the Larmor orbit was larger than the region of a strong radial electric field.
Sigman, D. R.↗
Missions to comets
Missions to comets are outlined that form the basis for a new program to send a space probe to a comet. Simple flythroughs of the comet head will provide information about the composition of the ionized and neutral particles that make up the cometary atmosphere and on effects of solar-wind interaction with the comet. Projected are missions to the comets Grigg-Skjellerup, Encke, and Halley.
Farquhar, R. W.↗
Parametric study of ion heating in a burnout device (HIP-1)
Results of further studies on the Lewis Research Center hot-ion plasma source (HIP-1) are reported. Changes have been made in both the electrode geometry and materials to produce higher ion temperatures. Ion temperature increased significantly with increased vacuum pumping speed. The best ion temperatures achieved, so far, for H(+), D(+), and He(+) plasmas are estimated to be equal to, or greater than 0.6, equal to, or greater than 0.9, and equal to, greater than 2.0 keV, respectively. Electrode pairs produced high ion temperatures whether on the magnetic axis or off it by 5.5 cm. Multiple sources, one on-axis and one off-axis, were run simultaneously from a single power supply by using independent gas feed rates. A momentum analyzer has been added to the charge-exchange neutral particle analyzer to identify particles according to mass, as well as energy. Under any given plasma condition, the higher mass ions have higher average energies but not by as much as the ratio of their respective masses.
Sigman, D. R.↗
Cross section calculations of astrophysical interest
Cross sections are discussed for rotational excitation associated with theories of absorption and emission lines from molecules in space with emphasis on H2CO, CO, and OH by collisions with neutral particles such H, H2, and He. The sensitivity of the Thaddeus equation for the H2CO calculation is examined.
Gerjuoy, E.↗
Hot ion plasma heating experiments in SUMMA
A new superconducting magnetic mirror apparatus (SUMMA) is described using photographs, diagrams, characteristics graphs, and block diagrams. The apparatus consists of a magnet facility, a plasma test section, the electrode assembly, a charge-exchange neutral particle analyzer, and apparatus for emission spectroscopy. Initial results of hot ion plasma heating experiments conducted in this facility are reported. The purpose of these experiments was twofold: (1) to make a reliable electrode assembly for steady-state operation in the new SUMMA magnetic field configuration and test-section geometry; and (2) to see how ion heating scales as the midplane magnetic field is varied up to 3.5 tesla.
Reinmann, J. J.↗
The AEROS mission
The principal objective of the two AEROS satellites is the study of the physical and chemical processes in the earth's upper atmosphere and ionosphere by means of simultaneous measurements of various parameters. The parameters include the neutral atmosphere composition and density, the ion composition and density, electron density and flux of suprathermal electrons, and the solar EUV ionizing radiation. Temperature measurements of neutral particles, ions, and electrons are also conducted. The scientific payload is discussed along with details regarding the satellite orbits.
Laemmerzahl, P.↗
The neutral atmosphere temperature experiment
The AEROS Neutral Atmosphere Temperature Experiment (NATE) is designed to measure the kinetic temperature of molecular nitrogen in the thermosphere. A quadrupole mass spectrometer tuned to N2 measures the N2 density variation in a small spherical antechamber having a knife-edged orifice which is exposed to the atmosphere at the outer surface of the spacecraft. The changing density of N2 due to the spinning motion of the spacecraft permits determination of the velocity distribution of the N2 from which the temperature is calculated. An alternate mode of operation of the instrument allows measurement of the other gases in the atmosphere as well as N2 permitting determination of the neutral particle composition of the atmosphere.
Spencer, N. W.↗
Ion and electron temperatures in the SUMMA mirror device by emission spectroscopy
Ion temperatures were obtained in the SUMMA mirror device by observing the Doppler-broadened charge-exchange component of the 667.8and 587.6-nm He lines in He plasma and the H alpha and H beta lines in H2 plasma. The second moment of the line profiles was used as the parameter to determine ion temperature. Corrections for magnetic splitting, fine structure, monochromator slit function, and variation in charge-exchange cross section with energy are derived and included. Even for constant cross section, no magnetic splitting or fine structure, and infinitely narrow slit function, the line profile is not Gaussian, because the excitation results from a change-exchange process. Comparison is made with temperatures from a neutral particle analyzer.-
Patch, R. W.↗
Hot ion plasma heating experiments in SUMMA
Initial empirical results are presented for the hot-ion plasma heating experiments conducted in the new SUMMA (Superconducting Magnetic Mirror Apparatus) at NASA Lewis Research Center. A discharge was formed by applying a radially inward dc electric field near the mirror throats. Data were obtained at midplane magnetic flux densities from 1.0 to 3.5 tesla. Charge-exchange neutral particle energy analyzer data were reduced to ion temperatures using a plasma model that included a Maxwellian energy distribution superimposed on an azimuthal drift, finite ion orbits, and radial variations in density and electric field. Using this plasma model, the highest ion temperatures computed were 5 keV, 1.2 keV, and 1 keV for He(+), H2(+), and H(+), respectively. These were obtained at a midplane magnetic flux density of 1.6 T.-
Reinmann, J. J.↗
The atmosphere of Io from Pioneer 10 radio occultation measurements
The occultation of the Pioneer 10 spacecraft by Io (JI) provided an opportunity to obtain two S-band radio occultation measurements of its atmosphere. The day-side entry measurements revealed an ionosphere having a peak density of about 60,000 el/cu cm at an altitude of about 100 km. The topside scale height indicates a plasma temperature of about 406 K if it is composed of Na(+) and 495 K if N2(+) is principal ion. A thinner and less dense ionosphere was observed on the exit (night side), having a peak density of 9,000 el/cu cm at an altitude of 50 km. The topside plasma temperature is 160 K for N2(-) and 131 K for Na(+). If the ionosphere is produced by photoionization in a manner analogous to the ionospheres of the terrestrial planets, the density of neutral particles at the surface of Io is less than 10 to 1 trillion per cu cm, corresponding to a surface pressure of less than 10 to 1 nanobars.
Kliore, A. J.↗
Partition function corrections
The vibration-rotation interaction coupling in diatomic molecules is analyzed and first-order expressions for the energy levels are deduced. Corrections to the partition function to account for this coupling are derived. The effects of long-range intermolecular forces due to induced dipole-induced dipole interactions, dipole-induced dipole interactions, charge-dipole interactions, and charge-charge interactions are considered. London's quantized oscillator model of the induced dipole-induced dipole interaction is developed. The partition function including effects of such dispersion forces is derived and is shown to lead to the virial equation of state. For a model combining the hard sphere and long-range attractive type potentials, this is found to lead to the van der Waals equation of state. The equation of state near the critical point is presented in reduced form (thermodynamic variables expressed in units of critical point values). Finally, approximate corrections to the electronic partition functions are derived to account for perturbations of excited electronic states induced by neighboring neutral particles, heavy ions, and fast electron collisions.
Source record↗
On the oxygen and nitrogen enhancements observed in low energy cosmic rays
Fisk et al. (1974) have suggested that neutral particles are ionized in the solar cavity, are subsequently picked up by the solar wind, obtaining energies of about 1 keV/nucleon, and may be further accelerated to about 10 MeV/nucleon in the interplanetary medium. The requirements for this acceleration are examined, and a possible acceleration model is outlined. The acceleration must be performed in a time less than the dwell time of the interstellar ions in the solar cavity and must compete successfully against adiabatic cooling. The energy required for the acceleration must be less than the energy available in variations in the solar wind flow. The accelerator must act inefficiently on solar wind electrons and protons, and perhaps upon the majority of interstellar ions. It is shown that these requirements can be satisfied by a model in which acceleration results from transit-time damping of long-wavelength magnetosonic turbulence.
Fisk, L. A.↗
An alternative interpretation of Jupiter's 'plasmapause'
It has recently been suggested that Io is an important source of ions for the plasma detected by Pioneer 10 in the inner magnetosphere of Jupiter. Assuming this to be true, we show that near the orbit of Io the central collector of the Pioneer-10 plasma instrument could detect only inwardly diffusing ions created at a radial distance greater than that of the spacecraft. The rapid decrease in ion density observed beyond Io's orbit is attributed, at least partially, to this effect and thus may not represent a real plasma boundary such as a 'plasmapause'. Instead, the drop in observed ion density could correspond to a decrease in the density of Io-associated neutral particles orbiting Jupiter.
Neugebauer, M.↗
Field ionization device used for measuring the pulse height defect of He/+/ in silicon
A neutral particle detector using field ionization and liquid-nitrogen-cooled solid state detectors has been developed to investigate the pulse height defect of low energy He(+) ions in silicon. The field ionization tip is fabricated from a short length of tungsten wire; a typical detector is of the surface-barrier Si type with a thin Au window and low capacitance (about 15 pF); the assembly is mounted in a cylindrical vacuum chamber which is pumped to about 10 to the -6th torr. As an example, pulse height distributions for He(+) and H(+) taken at tip bias of 25.7 kV are presented. The detected energy of the H and He ions are studied as a function of the actual energies of accelerated ions, for a detector having a gold front conducting surface layer of 32 micrograms/sq cm.
Curtis, C. C.↗