Test and Development of the High Powered Helicon Thruster

What is a Helicon Thruster? HPH is a type of plasma rocket engine that uses electromagnetic energy to achieve thrust. HPH differs from conventional ion engines by eliminating the need for high voltage electric fields during operation. As a result HPH is more reliable and has promising potential for higher thrust application.

Benefits of Plasma Propulsion Over Chemical Propulsion HPH operates under the same principles of chemical rocket propulsion: law conservation of momentum fuel/rocket system: P = 0 fuel/rocket system: P = 0

CHEMICAL PROPULSION: Only way to increase rocket kinetic energy is to increase the mass of the fuel. increasing fuel means increasing weight which means kinetic energy is being wasted in accelerating the fuel! EXTREMELY INEFFICIENT PLASMA PROPULSION: Allows for us to increase the rockets final velocity by increasing the exhaust velocity. That means for equal masses of fuel the plasma rocket can attain a higher kinetic energy than chemical rockets. Safer: fuel used for HPH is Argon (inert gas). Higher precision throttling is possible. Can only operate in a vacuum.

How it Works 1.High powered (tens of kW), RF waves energize a cloud of argon gas enough to were it becomes a plasma. Quartz tube Helicon Antenna Plasma Containment Coil The containment coil produces magnetic field lines within the quartz tube which work to localize and maintain the plasma.

How it works 2.Once the gas is a plasma the pulsed EM waves accelerates the gas. Exhaust velocities are directly proportional to the supplied power.

Our Goal Study the plasma flow dynamics to achieve better efficiency. Study the change in the Z component B-field as a function of axial distance and time. Diagnostic tool:B-dot Probe Study the change in plasma radial density. Diagnostic tool:Langmuir Probe We want plasma flow to be axial NOT RADIAL.

Experimental Setup All tests were done under pressures of 10^-6 Torr, equivilently 10^-9 atm. A HIGH POWERED (10kW), pulse (approximately 2us) is sent through the antenna. Up to 100 test fires are taken measuring the changing axial B- field or the radial plasma densities at 2cm intervals. Data is acquired via fiber optic lines and plotted using Labview. Face of HPH First magnetic nozzle Langmuir probe Original B-dot probe

Experimental Setup Vacuum chamber housing HPH Langmuir probes measuring radial plasma density at different axial positions

Data Acquired Labview synthesizes every test run under a common time domain. Shows how changes in axial magnetic fields propagate and decay. Decay is similar to base field decay! What does this mean: The axial current pulse diminishes with distance. Conclusion: Axial B-field must have less of a decay This will focus the plasma beam increasing plasma velocity.

Next Step In order to have higher energy transmission into the plasma’s axial momentum, the decision was made to add a second magnetic nozzle.

What I did While the nozzle and new power supply were being fabricated I had to: 1. Build a new B-dot probe to replace the less accurate one in use. 2.Design a new triggering circuit for HPH thruster

B-dot Finished B-dot probe was covered in high vacuum epoxy to prevent out gassing while in the chamber The original probe’s dimensions were based off an earlier thruster

Triggering circuit Basic design specs: Capable handling more power than the original need to operate under 15 V logic provide the option of EM shielding completed on PCB. Each IGBT can handle 240 Amps pulsed at 1200V!

New Setup New B-dot Second nozzle

From a slightly different angle.

And another view

Application of HPH thruster Laser Interferometer Space Antenna (LISA) precision adjustment of satellites. Satellite attitude control. Deep space missions.

Current work Designing a remote control system for the second nozzle’s power supply. Will be much safer for the person operating.

Acknowledgements Thanks to: Washington Space Grant Consortium Dr. Robert M. Winglee Race Roberson Jim Palmer