A linear reactor system with impurity seeded multiple-mirror end plug

Multiple-mirror end-plugged linear reactor parameters are estimated including parallel electron thermal conduction loss which was not taken into account in the previous papers in spite of its importance. The assumed thermal conductivity in a multiple-mirror is simply 1/m2 times the classical value. Impurity seeding only at the plugs is demonstrated to be effective for increasing the energy confinement time of the plasma and consequently reducing the reactor length by more than a factor 1.5. Total length of the reactor is optimized along with plasma temperature, plug length, and seeding fraction of the impurity. A typical reactor length for B = 100 kG and Q sub(E) = 2 is calculated to be about 1100 m with an output power of 13 GW. It is proposed to attach a magnetic bubble made of a high order multipole or SURMAC field to the end of the system. Transient low plasma density in the bubble may well improve thermal insulation of the plasma and the bubble may be effective for pulsed linear systems. The necessary volume of such a bubble for a pulsed fusion reactor of n tau sub(E) = 5 x 1014 cm-3 and T = 5 x 103 eV is estimated to be 45 m3. (auth.)