Summarized results of the Artificial Auroral Experiment, Precede

Abstract

A 2‐kW electron accelerator was launched in October 1974 from the White Sands Missile Range, New Mexico, as the initial launch in the Excede series of artificial auroral experiments. The launch, designated Precede, was supported by a number of ground‐based optical systems to record the electron‐induced atmospheric emissions as a remote diagnostic technique of accelerator performance in addition to recording emissions of aeronomic interest in a controlled artificial aurora. The electron source, square wave modulated at 0.5 Hz, was initiated at 95 km on payload ascent and continued through apogee (120 km) to a descent altitude of approximately 80 km, providing a total of 90 pulses of the 2.5‐kV 0.8‐A electron beam over a period of 180 s. A rocket‐borne retarding potential analyzer provided a measure of the energy distribution of electrons returning to the vehicle skin. The energy distribution of the return current electrons has been compared with laboratory measurements of the energy distribution of secondary electrons as a function of scattering angle to infer a vehicle potential due to a net positive charge buildup on the electron‐emitting payload. The steady state vehicle potential at apogee is less than 30 V, with substantially smaller values determined at lower altitudes. Langmuir probe theory is shown to model accurately the altitude dependent steady state vehicle potential. Ground‐based optical systems included an image‐intensified spectrograph and a dual channel telephotometer recording the time dependent emission profile of the N2+ (B²Σu+ → X²Σg+) first negative (0‐0) band at 3914 Å and the O(¹S → ¹D) transition at 5577 Å. The spectrograph recorded emissions in the 4200‐ to 8500‐Å wavelength range including the prominent transitions of the N2+ first negative, N2(B³Πg → A³Σu+) first positive and N2+ (A²Πu → X²Σg+) Meinel systems as well as the O(¹S) 5577‐Å line. With the exception of the N2+ first negative system the image‐intensified spectrograph indicated that these emissions are collisionally deactivated in the 80‐ to 110‐km altitude range. The ground‐based telephotometer measurements were corrected for the effects of atmospheric extinction by monitoring the apparent photon emission rates of several bright stars. An electron‐induced luminous efficiency of (4.5 ± 0.4) × 10−3 was determined for the N2+ 1 N (0‐0) transition at 3914 Å in the 80‐ to 100‐km altitude range.

Infrared emission from NO (Δυ=1) in an aurora: Spectral analysis and kinetic interpretation of HIRIS measurements

“…The close coupling of the NO and N2 + emissions indicates that the production of vibrationally excited NO is directly related to electron impact processes in the aurora. This finding is consistent with previous broad-band observations of NO vibrational emission in an aurora[Stair et aL, 1975;Baker et aL, 1977].The number of photons of NO fundamental band radiation emitted per ion pair produced in the aurora may be deduced from the NO/N2 + band intensity ratios using the fact that in electron irradiated air •20 ion pairs are created for every 391.4-nm photon radiated, as measured both in the laboratory[Hirsch et aL, 1970] and in the field[O'Neil et aL, 1978]; the results of this evaluation are given inTable 2. With one exception the results are highly consistent with each other, particularly in view of the uncertainties involved in estimating the N2 + column intensities.…”

Rotating Electrons Discharge Model for a Spacecraft Emitting a High Power Electron Beam in Space

“…In the experiment, a luminous region around the rocket was also detected by ground-based TV system. In the Excede series of artificial aurora A electron beam, an illuminated region around the rocket symmetric with respect to the magnetic field, just the same as observed in the present experiment, was observed from ground (O'NEIL, 1978). A large amount of the plasma production near the vehicle was directly detected by on-board Langmuir probe in the Japanese sounding rocket experiment.…”

Remote X ray measurements of the electron beam from the EXCEDE III Experiment

“…is an atmospheric energy deposition rocket experiment that was launched on April 27, 1990, from the White Sands Missile Range (WSMR). This flight is the most recent in a .series of such experiments [e.g., O'Neil et al, 1978aO'Neil et al, , b, 1982]. An artificial aurora was successfully produced between the altitudes of-62 and 115 km by an electron beam with an injected primary electron energy of-2.5 keV and current of-18 A.…”