Investigation of a space propulsion concept using inertial electrostatic confinement

This thesis discusses the Helicon Injected Inertial Plasma Electrostatic Rocket (HIIPER), a space propulsion concept consisting of a helicon source for plasma generation and an ion extraction method using a nested pair of inertial electrostatic confinement (IEC) grids that are asymmetrically designed. In this study, which used argon as a propellant, a retarding potential analyzer (RPA) was used to measure the exhaust of HIIPER, and results showed the presence of electrons and ions, with ion energies equal to the helicon bias voltage and electron energies on the order of the inner IEC grid voltage. Electron energy distributions were also generated. Quasineutral exhaust conditions were measured to occur with the inner IEC grid between 2 and 3 kV (negative). Tests on the IEC grid configuration were also performed, which indicated that electrons preferentially exited the asymmetry of the inner IEC grid. Langmuir probe measurements showed that some ion losses occurred due to the experimental setup. These losses were reflected in thrust measurements at the exhaust of only a few micronewtons. However, with improvements to the facilities and experimental setup, improvements in thruster efficiency would likely be obtained. While additional analysis would be required to fully characterize HIIPER, the results thus far show promising quasineutral behavior and demonstrate an innovative cathode design for electric propulsion applications