Spatial distribution of energy deposited in nitrogen by electrons

The spatial distribution of the energy deposited by kilovolt electrons moving through gaseous molecular nitrogen was measured. The range of electrons of initial energy 300 eV to 5 keV was obtained and can be expressed by the formula R=K1+K2EA1−K3EA2, where R is the range, E is the initial energy of the electrons, and Ki,Ai are constants. The range, in this energy interval, is greater than that determined by previous measurements. A source of error, not previously discussed, is considered. The energy region (above 1 keV) where the simpler expression R=KEA holds is discussed. It is shown that this is the energy region where the energy and range dependence of the energy deposition curve can be removed and a normalized, characteristic energy deposition curve λ can be obtained. The efficiency of conversion of electron energy at 1 keV and 280 μ pressure to energy of photons at 3914 Å was measured to be (0.28±0.03) %.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69995/2/JCPSA6-64-2-743-1.pd

A technique for recovering the vertical number density profile of atmospheric gases from planetary occultation data

The occultation technique of determining the properties of the atmosphere using absorption spectroscopy is examined. The intensity of a star, in certain atmospheric absorption bands, is monitored by a satellite tracking the star during occultation by the Earth's atmosphere. The intensity data in certain wavelength intervals, where absorption is attributed to a single species, are related to the tangential column number density of the absorbing species through Beer's law. The equation for the tangential column number density is the Abel integral equation which is inverted to obtain the number density profile of the absorbing species at the occultation tangent ray point. Two numerical schemes for inverting the Abel integral equation for signals of low intensity with statistical noise superimposed are presented; one for determining the number density profile of atmospheric species that decrease exponentially with height, and the second for determining the profile of constituents having a more complex vertical structure, such as ozone. The accuracy of retrieving the number density distribution from planetary occultation data is examined. A theoretical analysis of the errors in determining the number density from occultation data of very low signal intensity is also presented. The errors in retrieving the number density profile are related to the intensity of the source, the number of data points per scan, and the degree of data smoothing required before inversion. As a specific example, calculations are made of the errors in retrieving the molecular oxygen and ozone number density profiles from occultation intensity data in the Schumann-Runge continuum of molecular oxygen at 1450 A and the Hartley continuum of ozone at 2450 A.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34033/1/0000310.pd

Brightness of the O2 atmospheric bands in the daytime thermosphere

The Fabry-Perot interferometer on Dynamics Explorer 2 was used as a low sensitivity photometer to study the O2 Atmospheric A band during the daytime. A study of the brightness of the emission showed that the assumed source of O2(b1[Sigma]g+) in the thermosphere, O(1D), can account for the observed intensity up to about 250 km but with a significantly different scale height. This combined with an enhanced brightness above this altitude suggests an additional source for this emission.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25793/1/0000355.pd

Thermal electron energy distribution measurements in the ionosphere

Results of electron spectrometer and cylindrical Langmuir probe measurements of ionospheric electron energy distribution in the range from about 0[middle dot]2 eV to 4[middle dot]0 eV are presented and discussed in this paper.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33842/1/0000100.pd

Remote sensing of mesospheric winds with the high-resolution doppler imager

Observations of the winds in the upper atmosphere obtained with the High-Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) are discussed. This instrument is a very stable high-resolution triple-etalon Fabry-Perot interferometer, which is used to observe the slight Doppler shifts of absorption and emission lines in the O2 Atmospheric bands induced by atmospheric motions. Preliminary observations indicate that the winds in the mesosphere and lower thermosphere are a mixture of migrating and non-migrating tides, and planetary-scale waves. The mean meridional winds are dominated by the 1,1 diurnal tide which is easily extracted from the daily zonal means of the satellite observations. The daily mean zonal winds are a mixture of the diurnal tide and a zonal flow which is consistent with theoretical expectations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29716/1/0000050.pd

On the loss of gases from a planetary atmosphere

An analysis of the collisional transition between the lower atmosphere and the collisionless exosphere is carried out based upon an integral formulation of the Boltzmann equation. This investigation utilizes a collision model which is a combination of Lorentz-gas and relaxation collision models. The results of this analysis indicate that intermolecular collisions act in two ways to affect the atmosphere. First, there is a critical layer, similar to the apparent photospheric surface of the Sun, from which the material escaping from the planet originates. This layer is determined by collision suffered by particles moving on orbits which skim tangentially by the planet. Secondly, collisions reduce the vertical flux of material in a manner analogous to the diffusion processes which occur in the lower atmosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31960/1/0000002.pd

Magnetic ordering of the polar airglow

The visible airglow experiment on the Atmosphere Explorer-C satellite has gathered sufficient data over the Earth's polar regions to allow one to map the geographic distribution of particle precipitation using emissions at 3371 and 5200 A. Both of these features exhibit large variations in space and time. The 3371 A emission of N2(C3[pi]), excited by low energy electrons, indicates substantial energy inputs on the dayside in the vicinity of the polar cusp. More precipitation occurs in the morning than evening for the sample reported here, while the entire night sector between magnetic latitudes 65[deg] and 77.5[deg] is subjected to particle fluxes. Regions of enhanced 5200 A emission from N(2D) are larger in horizontal extent than those at 3371 A. This smearing effect is due to ionospheric motions induced by magnetospheric convection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22624/1/0000174.pd

Carbon dioxide and monoxide above the troposphere

The dependence of the atmospheric distributions of CO2 and CO upon the combined effects of photochemical production and loss, and transport is examined. It is found that, for CO2, deviations from complete mixing are possible in the mesosphere and upper stratosphere. Further, sufficient quantities of CO may be maintained, as a product of CO2 photodissociation, to be aeronomically significant.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32655/1/0000020.pd

The influence of thermospheric winds on the auroral red-line profile of atomic oxygen

The effect of thermospheric winds on the emission profile of [lambda]6300 is discussed. It is shown that meridional winds play a significant role in determining the shape of this emission and the conventional diffusion of O(1D) hypothesis, though important, is not adequate to explain the observed features completely.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33565/1/0000066.pd

Optical effects of spacecraft-environment interaction Spectrometric observations by the DE-B satellite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76162/1/AIAA-1983-2657-139.pd