Beam Experiment Aboard Rocket (BEAR)
The Beam Experiment Aboard Rocket (BEAR) experiment tested a neutral particle beam accelerator during a suborbital rocket flight. The Beam Experiment Aboard Rocket accelerator is the major component of an experiment designed to demonstrate the operation of an ion accelerator in space and to characterize the exoatmospheric propagation of a neutral particle beam. It is designed to produce a 10-mA (equivalent), 1-MeV, neutral hydrogen beam in 50-µs pulses at 5 Hz. The accelerator consists of a 30-kV, H- injector, a 1-MeV radiofrequency quadrupole, two 425-MHz RF amplifiers, a gas-cell neutralizer, beam optics, a vacuum system, diagnostics, and controls. The design has been constrained by the need for a light-weight rugged system that would operate autonomously.
Charged hydrogen ions that escaped neutralization might play havoc with an NPB satellite. The accumulation of charge might severely degrade weapon system performance in unforeseen ways, although NPB scientists are confident that this would not bean issue. The Beam Experiment Aboard Rocket (BEAR) experiment with an ion source was designed to answer any remaaining doubts about space-charge accumulation.
The design of this 1-m-long, lightweight (greater than 55 kg) accelerator incorporates four aluminum vane/cavity quadrants joined by an electroforming process. With the vane and cavity fabricated as a monolithic structure, there are no mechanical RF, vacuum, or structural joints. The accelerator had undergone extensive environmental and operational laboratory testing by early 1989 in preparation for launch. Because of the rigors of spaceflight, the accelerator design has been constrained by factors not normally applicable to conventional terrestrial accelerators. The design techniques developed for BEAR would be applicable whenever, rugged, lightweight, or power-efficient systems are required.
On July 13, 1989 the Beam experiment Aboard Rocket (BEAR) linear accelerator was successfully launched and operated in space. The flight demonstrated that a neutral hydrogen beam could be successfully propagated in an exoatmospheric environment. The accelerato was the result of an extensive collaboration between Los Alamos National Laboratory and industrial partner. The design was strongly constrained by the need for a lightweight rugged system that would survive the rigors of launch and operate autonomously. Following the fight the Beam Experiment Aboard Rocket (BEAR) payload was recovered with minimal damage via parachute after an 11-minute flight to a maximum altitude of 195 km.
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