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Evaluation of the Neutron and Gamma-Ray Heating in the Radiation Shielding and Magnet Coils of the VISTA Spacecraft

Sümer Sahin, Haci Mehmet Sahin, Adnan Sözen

Fusion Science and Technology

Volume 33 / Number 4 / July 1998 / Pages 418-434


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Basic nuclear data for a design concept with inertial fusion energy propulsion for manned or heavy cargo deep space missions beyond earth orbit have been evaluated. Fusion power deposited in the inertial confined fuel pellet debris delivers the rocket propulsion with the help of a magnetic nozzle.

The superconducting magnets of the magnetic nozzle are protected against neutron and gamma-ray radiation by a massive shielding. Throughout the shielding, the nuclear heating, caused by neutrons and gamma rays has been calculated. As a critical issue for this design concept, special attention is paid to the nuclear heating in the superconducting magnet coils. The neutron and gamma-ray penetration into the coils is calculated using the Sn methods with a high angular resolution in r-z geometry in S16 P3 approximation by dividing the solid space angle in 160 sectors.

Total peak nuclear heat generation density in the coils is calculated as 64.5 W/cm3 by a fusion power of 17 500 MW. Peak neutron heating density is 30.8 W/cm3, and peak gamma-ray heating density is 40.6 W/cm3 (on a different point). However, volume-averaged heat generation in the coils is much lower, namely, 2.17, 8.49, and 10.66 W/cm3 for neutron, gamma-ray, and total nuclear heating, respectively.

A conically shaped frozen hydrogen expellant reduces the neutron streaming toward the spacecraft by a factor of ~12.5 via neutron scattering on hydrogen and deflection into vacuum, in addition to the geometric neutron flux attenuation in space by 1/r2. The results of these calculations can help to increase the credibility of the vehicle for interplanetary space transport applications design concept.

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