Design, construction, and testing of a photoelectronic UV-B personnel dosimeter whose optical system and thus wavelength and angular response match closely the Robertson-Berger sunburn ultraviolet meter is described. Erythema1 irradiance is sensed by a MgWO, fluor, and cumulative exposure is stored in digital form by custom-built hybrid microcircuits for readout through a microcomputer at a central station or a field display unit. Sensitivity and exposure storage capacity are designed to provide research-standard precision in measurements of a few hours to 5 2 months duration, and a high level of temperature stability has been achieved. The dosimeter's compactness, rugged and waterproof construction, and wide dynamic range make it applicable to laboratory and environmental photobiology research as well as in skin cancer epidemiology studies.

Spatial distributions of energy deposition rates in EXCEDE Spectral's 3 keV, 7 A electron beam injection at E region altitudes derived from onboard photographic images of the air fluorescence are presented and compared with a time‐dependent computational model of the collective beam‐plasma interaction. The volume excitation rates decrease with a scale length of order 1 m near the rocket, are ∼2 orders of magnitude greater than predicted from single particle transport calculations, and at fixed distances from the accelerator vary by less than a factor 3 over an ambient density range of at least 40. The data are consistent with a discharge model in which the driving beam plasma instability is an absolute hydrodynamic instability with energy deposition controlled by trapping and axial dimension by ambipolar expansion of the plasma.

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