A computational procedure for describing transport of electrons in condensed media has been formulated for application to effects and exposures from spectral distributions typical of electrons trapped in planetary magnetic fields. The procedure is based on earlier parameterizations established from numerous electron beam experiments. New parameterizations have been derived that logically extend the domain of application to low molecular weight (high hydrogen content) materials and higher energies (approximately 50 MeV). The production and transport of high energy photons (bremsstrahlung) generated in the electron transport processes have also been modeled using tabulated values of photon production cross sections. A primary purpose for developing the procedure has been to provide a means for rapidly performing numerous repetitive calculations essential for electron radiation exposure assessments for complex space structures. Several favorable comparisons have been made with previous calculations for typical space environment spectra, which have indicated that accuracy has not been substantially compromised at the expense of computational speed.Nealy, John E. and Anderson, Brooke M. and Cucinotta, Francis A. and Wilson, John W. and Katz, Robert and Chang, C. K.Johnson Space Center; Langley Research CenterAEROSPACE ENVIRONMENTS; ELECTRON TRANSFER; PLANETARY MAGNETIC FIELDS; PARAMETERIZATION; EXTRATERRESTRIAL RADIATION; BREMSSTRAHLUNG; ELECTRON BEAMS; LOW MOLECULAR WEIGHTS; LARGE SPACE STRUCTURES; RADIATION DOSAGE

"This symposium was organized to bring together the multidisciplinary expertise required to assess risk of exposure to space radiation.... Topics addressed ranged from what is known or predicted about radiation environments for human exploration, and what shielding would be required based on ALARA radiation protection guidelines. The development of new physics cross section models, and improved ion beam transport codes was reported, as well as biological demonstrations of the consequences of specific shielding materials and applications to manned missions to Mars and beyond. Advancements in the biological measurements of radiation-induced protein expression profiles, membrane damage, bystander effect, and adaptive response were presented, and countermeasures evaluated. Finally several presentations addressed specific approaches to integrate the physical and biological parameters in order to assess key elements of the risk and the associated uncertainties."--Page 1277.

Throughout most of the twentieth century, electric propulsion was considered the technology of the future. Now, the future has arrived. This important new book explains the fundamentals of electric propulsion for spacecraft and describes in detail the physics and characteristics of the two major electric thrusters in use today, ion and Hall thrusters. The authors provide an introduction to plasma physics in order to allow readers to understand the models and derivations used in determining electric thruster performance. They then go on to present detailed explanations of: Thruster principles Ion thruster plasma generators and accelerator grids Hollow cathodes Hall thrusters Ion and Hall thruster plumes Flight ion and Hall thrusters Based largely on research and development performed at the Jet Propulsion Laboratory (JPL) and complemented with scores of tables, figures, homework problems, and references, Fundamentals of Electric Propulsion: Ion and Hall Thrusters is an indispensable textbook for advanced undergraduate and graduate students who are preparing to enter the aerospace industry. It also serves as an equally valuable resource for professional engineers already at work in the field.

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