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Banks, P. M.

Publications and source records attributed to Banks, P. M..

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Electric field observations by incoherent scatter radar in the auroral zone.

Analysis of ion drift velocity measurements, made for a 24-hour period in February 1972 by the incoherent scatter radar at Chatanika, Alaska (L = 5.7), provides a detailed view of electric fields and currents in the auroral zone. Large northward electric fields were seen in the evening sector, and an abrupt change to southward occurred at the start of a midnight sector substorm. The westward electric field was generally much smaller than the north-south electric field but showed a rapid increase at the time of a westward auroral surge. Study of global magnetograms and all-sky camera photographs has led to the identification of five substorms during the 24-hour observation period. These substorms were sufficiently separated in time to allow identification of the electric field and current variations in late afternoon, evening, and morning local time sectors.

Banks, P. M.↗
NASA NTRS1973

Ion heating in thermal plasma flows.

The general effects of thermal plasma flows on the thermal structure of the upper ionosphere and inner magnetosphere are discussed. In the light of presented results, it is shown that thermal ions in the outer regions of the plasmasphere and beyond may be substantially hotter than previously thought.

Banks, P. M.↗
NASA NTRS1972

Direct measurements of plasma drift velocities at high magnetic latitudes.

Description of an incoherent scatter radar experiment performed at the 23-cm radar facility in Chatanika, Alaska. The experiment has provided a direct method for measuring the ionospheric plasma transport velocity vector over long periods with relatively good time resolution. Since the F-region transport at this site is closely associated with magnetospheric convection, particularly at night, the radar can provide important information about the behavior of the magnetosphere.

Doupnik, J. R.↗
NASA NTRS1972

Convection electric fields and polar thermospheric winds.

Use of the qualitative ideas of convection electric fields over the earth's polar regions to demonstrate the importance of ion drag in establishing a thermospheric wind system. Recent measurements indicate that uniform electric fields of 10 to 40 mV/m are a regular feature of the polar-cap ionosphere. Calculations of the neutral thermospheric wind, using these measured fields in a simple ionospheric model, have been made. The time scale for motion of the neutral gas ranges from less than 1 hour at F-region heights to about 2 hours in the dynamo region of the ionosphere. It has been found that the viscosity of the atmosphere is important in determining the winds in the dynamo region. Results are given that show ion-temperature enhancements of hundreds of degrees that are due to ion-neutral frictional effects. In addition, the total deposition rate of convection energy in the polar thermosphere is shown to be of the same order of magnitude as that due to absorption of solar EUV radiation. The implications of these results for the dynamics and energetics of the thermosphere are discussed.

Fedder, J. A.↗
NASA NTRS1972

The possibility of supersonic plasma flow in a collapsing post-sunset ionosphere.

As a result of the rapidly decreasing pressure in the topside ionosphere during twilight hours, a rapid downward flow of hydrogen plasma from the protonosphere takes place. In the case of steady state, isothermal, frictionless flow, the criterion for the existence of a critical point (transition to supersonic flow) above 1000 km is that the plasma temperature be lower than a certain limiting temperature which is a function of the field line considered. In the latitude region between 40 and 70 deg, this upper temperature limit varies from 963 to 1066 K. Since these temperatures are considerably lower than the observed temperatures, it follows that in the case of steady state, isothermal flow the velocities will always remain subsonic. When the effect of the neglected terms is examined, the temperature gradient is shown to exert the strongest influence on the nature of the flow. It is concluded that there is a definite possibility that supersonic downward flows in a post-sunset topside ionosphere may occur.

Fontheim, E. G.↗
NASA NTRS1972

Dynamical behavior of the polar topside ionosphere.

A review is given of magnetospheric interactions with the polar ionosphere using recent experimental and theoretical results. The effect of the polar wind is discussed with reference to the observational data of J. Hoffman. These and the results of other experiments support the concept of polar wind ion flows as a general feature of the topside ionosphere for all regions outside the plasmasphere. It is shown that most of the semi-permanent topside density features result from changes in plasma temperature and F2-region effects rather than being associated with changes in ion composition. Finally, the polar peak density enhancement is discussed in terms of recent observations of the polar cusp.

Banks, P. M.↗
NASA NTRS1972

Magnetospheric processes and the behavior of the neutral atmosphere.

A review is given of the quiet time couplings which exist between the magnetosphere and the thermosphere. Joule heating arising from aurorae and the combination of Joule heating and ion drag arising from magnetospheric convection normally provide as much energy to the thermosphere as solar ultraviolet radiation. Ion drag is especially important for establishing wind systems in the thermosphere. Using the qualitative ideas of convective electric fields, a description of a possible model of the global wind system is given. It is pointed out that the existence of a convectively driven wind source at high latitudes consistent with magnetospheric convection leads to the possibility of a mean easterly wind, i.e., super-rotation.

Banks, P. M.↗
NASA NTRS1971

Difficulties with thermal protons in the Venusian topside ionosphere.

An analysis of recent findings and studies is presented which shows that thermal protons of planetary origin are rapidly destroyed in the Venusian ionosphere, and thus cannot be the principal topside ions. He(+) is conjectural, whereas there might be a possibility that O(+) is present in significant density.

Banks, P. M.↗
NASA NTRS1970

Photoelectron fluxes in the ionosphere

Photoelectron fluxes and energy spectra in ionosphere for predawn and sunlit atmospheres, taking into account elastic and inelastic collisions

Banks, P. M.↗