0191-9067/80/030241-03S02.00/0 Copyright ° 1980 SUNSAT Energy Council MIDDLE ATMOSPHERE NO^ PRODUCTION DUE TO ION PROPULSION INDUCED RADIATION BELT PROTON PRECIPITATION A. C. AIKIN Laboratory for Planetary Atmosphere NASA/Goddard Space Flight Centei Greenbelt, Maryland 20771 C. H. JACKMAN Resident Research Associate National Academy of Sciences Abstract—The suggestion that KeV Ar+ resulting from ion propulsion operations during solar power satellite construction could cause energetic proton precipitation from the inner radiation belt is examined to determine if such precipitation could cause significant increases in middle atmosphere nitric oxide concentrations thereby adversely affecting stratospheric ozone. It is found that the initial production rate of NO (mole/cm3 sec) at 50 km is 130 times that due to nitrous oxide reacting with excited oxygen. However, since the time required to empty the inner belt of protons is about 1 second and short compared to the replenishment time due to neutron decay, precipitation of inner radiation belt protons will have no adverse atmospheric environmental effect. Ion propulsion has been suggested as a means of transporting large space structures constructed in low Earth orbit to geosynchronous orbit. Such a propulsion system might utilize argon, producing a beam of 5 keV Ar+ (1). Another study (2) suggests that such an Ar+ beam could induce plasma turbulence causing precipitation of the Mev protons contained in the inner radiation belt. Protons of similar energy are produced during large solar flares. When these protons precipitate into the middle atmosphere at high geomagnetic latitudes, ionization occurs in the 30 to 100 km altitude range (3,4). One of the results of such ionization is the production of nitric oxide, which at altitudes below 50 km influences the distribution of ozone. In this paper NO production due to dumping of inner radiation belt protons by ion propulsion operations is compared with natural sources of nitric oxide in order to assess the influence of ion propulsion operations involved in the construction of the solar power satellite on the terrestrial NO budget and its possible consequences for stratospheric ozone. The flux of protons within the inner radiation belt can be represented by Following the energy degradation scheme for protons in the atmosphere developed by (6) we degrade the spectrum given in equation (1) and compute the ionization rate. The rate of ionization is approximately equal to the production of NO molecules (7,8). The production rate of 1.25 NO molecules per ion pair recommended in Ref. (6) is adopted. The resulting NO production rate as a function of altitude is displayed in Figure 1 for a time of 1 second.
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