A.S. Pagan, E. Ferrer Gil, R.A. Gabrielli, G. Herdrich

Two magnetic confinement concepts, the Spherical Tokamak (ST) and the Field Reversed Configuration (FRC) are evaluated and compared with regards to their performance as core elements of fusion space propulsion systems operating by the working gas drive principle. To this end, two-dimensional, axisymmetric analytic models for the investigation of the respective magnetic confinement of the fusion plasma are selected, implemented and expanded to include the modelling of thermodynamic plasma quantities and energy transport phenomena. The introduction of a simple fusion criterion allows for the study of local ignition conditions and facilitates the establishment of an energy balance. Burning D-T and D-³He plasmas are considered for both confinement configurations. An approximate system mass breakdown for each of the proposed thruster systems is presented, exploring the approximate operational system range for both concepts and allowing for a direct comparison with regards to the mass specific power and overall feasibility. In general, D-T burning working gas fusion propulsion systems are shown to require the use of heavier blankets than comparable D-³He thrusters, making them considerably more massive and severely restricting their practicability due to throwing weight limitations of contemporary launchers. In direct comparison, the results indicate that a relatively massive fusion propulsion system based on the FRC appears to perform better when operated using the more attainable D-T fusion reaction. Contrastingly, higher mass-specific thrust powers are achieved for the ST when burning the more advanced D-3He reactant couples while also keeping the system mass within acceptable bounds. The absolute and mass-specific thrust powers attainable are shown to be mainly dependent on the system-bound scaling of the energy confinement time TE, with smaller values of TE permitting higher thrust powers. For the ST, there also appears to be a strong inverse connection between the reactor size and the massspecific power, prompting the development of small, light-weight fusion propulsion systems to maximise efficiency.

Deutscher Luft- und Raumfahrtkongress 2013, Stuttgart

Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn, 2013

Conference Paper

englisch

21,0 x 29,7 cm, 12 Seiten

urn:nbn:de:101:1-20131223782

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20.12.2013