NASA Langley Research Center
Hampton, Virginia

Ionizing Radiation Researchers

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• B.S. Physics, Rensselaer Polytechnic Institute (RPI)
• M.S. Physics, University of Lowell
• Ph.D. Physics, University of Lowell

Dr. Frederickson is a physicist at the Space Particles Branch of the Space Physics Division at Phillips Laboratory. Dr. Frederickson is an active member of several professional societies: Sigma Xi, ARRL, APS, AIAA, Material Research Society and IEEE (Senior Member). Presently, he is working on the effects of space radiation on spacecraft materials and on characterizing the space radiation belts with respect to their effects on materials. His research has spanned twenty-five years and he has investigated a number of topics involving radiation effects in electronic systems, components and especially insulator materials for a number of Air Force and NASA programs.

The topics which he has investigated can be summarized as follows:

• A search for rapidly annealing electrically active defects in silicon electronic materials after intense 50 MeV electron pulses.
• The profile of electrical currents induced in structures by high energy electron and photon radiations.
• Application of high energy irradiations to insulator structures.
• A model for the recombination-induced migration of defects in semiconductors and insulators.
• Dosimetry in complex structures. Experimental studies were pursued to measure the dose profiles in complex structures under high energy radiation.
• Electrical breakdown of insulating systems.
• Relating spacecraft tests of insulators in space radiations to ground tests and theories, including insulator test samples flown on the CRRES satellite.
• Secondary low-energy electron emission from irradiated surfaces. The energy spectrum is strongly perturbed by the state of the surface with some surfaces emitting essentially infinite electrons at essentially zero volts (negative electron affinity surfaces). In practical applications such as on spacecraft surfaces the secondary electron emission is not constant but varies perhaps up to a factor of two for common surfaces subjected to irradiation and contaminants over long periods.
• Conduction processes in insulating materials. There are critical needs for insulating polymers which will not store charge in space and will not produce electrical breakdowns or electrical noise pulses. Several candidate polymers were found, most notably pyrolized Kapton polyimide and polyvinylcarbazole. It was later seen that the prediction for Kapton is true; spacebased samples ceased storing significant charge after a few years when they had been pyrolized by space radiations.

The research results from his various projects were applied to a wide range of military systems both by direct contact with prime contractors and by technical discussions with engineering personnel. In addition, Dr. Frederickson published technical guideline documents which apply to many systems.

Dr. Frederickson's involvement with the LDEF project produced the following paper:

A.R. Frederickson, R.C. Filz, F.J. Rich and P. Sagalyn, Patterns of Discoloration and Oxidation by Direct and Scattered Fluxes on LDEF, Including Oxygen on Silicon, First LDEF Post-Retrieval Symposium, NASA CP-3134, 1991.

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