Bremsstrahlwung produced by precipitating electrons

Abstract

Theoretical values are presented of the bremsstrahlung flux escaping the atmosphere for various incident electron fluxes. The assumed incident electron fluxes were isotropic with exponential energy spectra. The escaping bremsstrahlung intensity, energy spectra, and angular d•stributions depend on the incident electron flux characteristics, indicating that measurements of bremsstrahlung can be used to derive information on the electron precipitation.

Simultaneous measurements of X-rays and electrons during a pulsating aurora

“…The ®rst model was developed by Berger and Seltzer (1972) and Seltzer and Berger (1974), and the second model by Walt et al (1979). These models are used to calculate the X-ray bremsstrahlung produced by energetic electrons that precipitate into the atmosphere.…”

“…Then we apply the model of Walt et al (1979) to ®nd the X-ray yield in the direction of the FOV of our X-ray detector. In our chosen azimuth sector 0 ±30 and time-interval (135±199-s¯ight time) the detector was looking at X-rays coming up at elevation angles of 33X4 to 54X3…”

“…By the combined use of two models, Berger and Seltzer (1972), Seltzer and Berger (1974) and Walt et al (1979), it is possible to deduce the electron precipitation that produces the measured X-rays, and make a comparison between the measured and the deduced electron¯uxes.…”

“…One model, developed on Berger and Seltzer (1972) and Seltzer and Berger (1974), is used to calculate the X-rays emitted into the upward hemisphere from a horizontal production layer. To take into account the angular distribution of X-rays escaping the atmosphere, we have used another model, developed by Walt et al (1979). Taking into account both scattering and absorption, these models make it possible to calculate both the angular scattering and the energy decrease resulting from the Compton eect.…”

“…Several models using dierent approximations and simpli®cations have been developed in order to calculate the yield of X-rays from electron spectra (Rees, 1964;Kamiyama, 1966;Freyer, 1969;Berger et al, 1970;Berger and Seltzer, 1972;Seltzer and Berger, 1974;Luhman and Blake, 1977;Walt et al, 1979;Khosa et al, 1984;Robinson et al, 1989;Gorney, 1987). Experiments have been performed to make simultaneous measurements of electrons and X-rays (Vij et al, 1975;Mizera et al, 1978;Goldberg et al, 1982;Datlowe et al, 1988), and the comparisons between measured and calculated X-rays have resulted in dierent degrees of agreement.…”