GAEP Capacitor Driving Pulsed Plasma Thruster

General Atomics Energy Products, a Division of General Atomics Electronic Systems

PRESS RELEASE
Contact: Randy Hartsock 858-522-8403
August 23, 2002, San Diego, CA

GENERAL ATOMICS ENERGY PRODUCTS CAPACITOR DRIVING PULSED PLASMA THRUSTER IN SPACE

General Atomics Energy Products (GAEP) announced today that its Model 34318 capacitor, developed for General Dynamics Space Propulsion Systems (GD-SPSS), has been operating in Earth orbit aboard NASA’s EO-1 spacecraft since January of 2002. This specially developed capacitor provides a high current, high voltage electrical pulse that drives a Pulsed Plasma Thruster (PPT). The PPT provides extremely precise attitude control thrust to keep the EO-1 spacecraft pointing in a specified direction during imaging of the Earth.

The thruster uses solid Teflon propellant and is capable of delivering very small impulse bits (low thrust per pulse) which are desirable for some precision pointing missions. At its lowest setting, the EO-1 PPT can nudge the spacecraft with an impulse comparable to a pin dropping from 4 inches onto your desk. The thruster consists of a coiled spring to feed the Teflon propellant, an igniter plug to initiate a small trigger discharge, the GAEP energy storage capacitor and electrodes. Plasma is created by the sudden change from a solid to a gas of the Teflon propellant caused by the discharge of the storage capacitor across the electrodes. The plasma is accelerated by an electromagnetic force in the induced magnetic field to generate thrust. By using a high velocity, low-mass propellant like Teflon, as opposed to conventional liquid fuel such as hydrazine, there is a higher net propulsion for a given energy input, thus saving substantial amounts of weight in fuel.

Energy Products developed a new capacitor dielectric system for this PPT application, designed to extend the life and increase the repetition rate capability of its Series M capacitors. The original Series M capacitors were used in the NOVA series spacecraft during the 1980’s and have accumulated more than 28 spacecraft-years of operation in precision station keeping (+/- 1 mm). This product type has also been used in military laser rangefinders, radars, and detonators, nuclear plant valve motors, and a variety of other applications.

NASA’s EO-1 Spacecraft

Photo: The GD-SPSS PPT for NASA’s EO-1 spacecraft.
The capacitor is housed in the central section of the device
and represents about a quarter of its total weight.
http://space-power.grc.nasa.gov/ppo/projects/eo1/img/c-98-2132.jpg

GAEP is a leading supplier of high energy density capacitors for large pulse power systems, medical defibrillators, lithotriptors, lasers, and accelerators, and a variety of other applications. GAEP is part of General Atomics Electronic Systems Inc., an affiliate company of General Atomics. The capacitor product line, formerly part of Maxwell Technologies, Inc., was purchased by General Atomics in March 2000. General Atomics Electronic Systems Inc. also designs and manufactures high voltage power supplies, radiation monitoring systems, and terminal automation products.