Generalized Lawson criterion for magnetic fusion applications in space

In this work a generalized burn criterion for thermonuclear fusion reactors for space is derived. It considers not only the most important subsystems distinguishing terrestrial from astronautic magnetic confinement fusion technology but also features like a variable hot ion mode, a variable fuel ratio and a ratio coupling fusion product ions confinement time with energy confinement time. The modeling is based on a power density flux model. Solving the energy and particle balance equations for the triple product, an analytical expression for a more general burn criterion is obtained. The results for commonly studied reactant couples (D–T; D–He3; He3–He3; B11–p) for a given energy confinement time and a given fusion product confinement time ratio are presented. Based on that, an exemplary comparative system mass analysis is performed. Within the frame of a thermally heated fusion plasma with a hot ion mode <2, the assessment shows that the purely aneutronic He3–He3 reaction is most impractical for space applications and that there are important technological challenges to be met in the case of the B11–p reaction.A generic system mass model is evaluated. Model improvements for future research activities are pointed out.