Advancements in Dense Plasma Focus (DPF) for Space Propulsion

The development of a dense plasma focus (DPF) propulsion device using p-B is described. A propulsion system of this type is attractive because of its high thrust-to-weight ratio capabilities at high specific impulses. From a fuel standpoint, p-B is advantageous because of the aneutronic nature of the reaction, which is favorable for the production of thrust since the charged particles can be channeled by a magnetic field. Different fusion mechanisms are investigated and their implication to the p-B reaction is explored. Three main requirements must be satisfied to reach breakeven for DPF fusion: a high Ti/Te ratio (~20), an order of magnitude higher pinch lifetime, and the reflection and absorption of at least 50% radiation. Moreover, a power re-circulation method with high efficiency must be available for the relatively low Q value of the DPF fusion reactor. A possible direct energy conversion scheme using magnetic field compression is discussed. DPF parameters are estimated for thrust levels of 1000 kN and 500 kN, and possible propulsion applications are discussed, along with developmental issues.