Tim Ziemba

Ion energy characteristics downstream of a high power helicon

The High Power Helicon eXperiment operates at higher powers (37 kW) and lower background neutral pressure than other helicon experiments. The ion velocity distribution function (IVDF) has been measured at multiple locations downstream of the helicon source and a mach 3–6 flowing plasma was observed. The helicon antenna has a direct effect in accelerating the plasma downstream of the source. Also, the IVDF is affected by the cloud of neutrals from the initial gas puff, which keeps the plasma speed low at early times near the source.

Mini-Magnetospheric Plasma Propulsion (M2P2): High Speed Propulsion Sailing the Solar Wind

Mini-Magnetospheric Plasma Propulsion (M2P2) seeks the creation of a magnetic wall or bubble (i.e. a magnetosphere) that will intercept the supersonic solar wind which is moving at 300–800 km/s. In so doing, a force of about 1 N will be exerted on the spacecraft by the spacecraft while only requiring a few mN of force to sustain the mini-magnetosphere. Equivalently, the incident solar wind power is about 1 MW while about 1 kW electrical power is required to sustain the system, with about 0.25–0.5 kg being expended per day. This nominal configuration utilizing only solar electric cells for power, the M2P2 will produce a magnetic barrier approximately 15–20 km in radius, which would accelerate a 70–140 kg payload to speeds of about 50–80 km/s. At this speed, missions to the heliopause and beyond can be achieved in under 10 yrs. Design characteristics for a prototype are also described.

Advances in High Power Beamed Plasma Propulsion

Magnetic nozzles offer the ability to provide highly collimated plasma streams that increase thruster efficiency by maximizing conversion of thermal energy into directed energy. However, in order to ensure that the plasma becomes detached from the field lines, the plasma must become super-Alfvenic as it traverses the nozzle. If the plasma is also supersonic, self-focusing of the plasma can occur due to the modification of the magnetic field by induce plasma currents that cause the magnetic field lines to be dragged outwards with the plasma. In so doing the subsequent plasma encounters a more convergent magnetic field configuration as it leaves the nozzle, enhancing the collimation. These processes are demonstrated through computer simulations and verified using a high power helicon for the thruster. Increase in transit times of a factor of 33% are demonstrated with the density being substantially enhanced along the axis of the magnetic nozzle. The plasma beam is used to beam power into a distant system at the end of the chamber. This remotely powered thruster is shown to be able to support very high densities and with excellent collimation, albeit at reduced specific impulse but without any onboard power. This experiment demonstrates the ability of using a beamed plasma system to power the propulsion of a remote spacecraft. Such systems could substantially reduce the cost of orbital transfers from low Earth orbit to geosynchronous orbit and even for planetary transfer orbits.