ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING, vol.27, pp.187-196, 2002 (SCI-Expanded)
An innovative concept for the direct utilization of fusion energy with laser ignited (D,T) capsules for propulsion is presented with the so called VISTA (Vehicle for Interplanetary Space Transport Applications) concept. VISTA's overall geometry is that of a 50degrees-half-angle cone to avoid massive radioactive shielding. The 50degrees-half-angle maximizes the jet efficiency, and is determined by selecting the optimum pellet firing position along the axis of the cone with respect to the plane of the magnet coil. The pellet firing position is in the vacuum. Assuming a total fusion power production of 17 500 MW with a repetition rate of 5 Hz and 3500 MJ per shot, the propulsion power in form of charged particles has been calculated as similar to7000 MW, making similar to40% of the total fusion power. About 60% of the fusion energy is carried by the leaking neutrons out of the pellet. Most of them (96%) escape into vacuum without striking the space ship. Only 4% enter the frozen hydrogen expellant in the conical shape (about 50 gr.). Two design limits are discussed, 5 and 1 mW/cm(3). Total peak nuclear heat generation in the coils is calculated as 4.7 mW/cm(3). The peak neutron heating is 1.9 mW/cm(3) and the peak gamma-ray heating density is 2.8 mW/cm(3). However, volume averaged nuclear heat generation in the coils is much lower. It is calculated as 0.18, 0.48, and 0.66 mW/cm(3) for neutron, gamma-ray, and total nuclear heating, respectively.