Assessment of Open Magnetic Fusion for Space Propulsion
- Paper number
IAC-06-C4.6.02
- Author
Prof. Claudio Bruno, University of Rome "La Sapienza", Italy
- Coauthor
Dr. Francesco Romanelli, ENEA, Italy
- Year
2006
- Abstract
The exploration of the SolarSystem requires advanced propulsion techniques. A rough estimate of the power required to accelerate a mass M to a velocità V in a time t yields an average power P = ( MV2/2)/ t. This estimate defines a characteriustic velocity V* = (2 a t)1/2 where a = P/ M is the so-called “specific power”. The distance to cover, L, is approximately given by L = k V t, with K is a constant of order one, depending on the particular shape of the orbital trajectory. Based on the definitions above,
a ( kW/ kg) ≈ 10−3 L2 ( AU)/ t3( yr) where 1 AU = 1 astronomical unit and t is in years. For instance, a Mars mission lasting 1 yr needs a of order 1.7 kW/ kg. An a of order 10 kw/ kg is roughly what is needed to explore the Solar System. The payload fraction is determined by the specific impulse, Isp, and likewise simple estimates indicate an Isp at least of order 104 s is required. The paper shows that a fusion system may meet these requirements. With the ITER fusion tokamak program under way, fusion appears on its way toward breakeven demonstration and the beginning of power generation. Generic fusion propulsion studies, reviewed in this paper, show that the a values required are feasible [1] provided a high fraction of fusion power can indeed used for direct thrust. In fact, fusion propulsion is more similar to chemical propulsion than fission, in that the fusion product themselves (He nuclei and H2 isotopes) may be the propellant, unlike with thermal or electric fission propulsion. Open magnetic field configurations are particularly suited to this purpose. Their present status, open issues and proposals for propulsion application are reviewed and discussed. The analysis focuse particularly on mirror configurations (tandem mirror and gasdynamic mirror), spheromaks and levitated dipoles, the most promising concepts in this regard. Their potential for practical development and their pluses and minuses are analyzed, and topics for future studies are accordingly suggested.
- Abstract document
- Manuscript document
IAC-06-C4.6.02.pdf (🔒 authorized access only).
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