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First Hispanic Astronaut Leads Plasma Propulsion Company

May 2, 2012

Ad Astra Rocket Company (AARC) is a spaceflight engineering company dedicated to the development of advanced plasma rocket propulsion technology. The company is developing the Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) and its associated technologies.

The company is located 3 miles to the West of the NASA Johnson Space Center, and about 25 miles to the South of the city of Houston, TX. AARC was incorporated on January 14th, 2005 and officially organized on the 15th of July of 2005.

Dr. Franklin R. Chang Díaz serves as company President and CEO. Dr. Chang Díaz invented the VASIMR® concept and has been working on its development since 1979, starting at The Charles Stark Draper Laboratory in Cambridge Massachusetts and continuing at the MIT Plasma Fusion Center before moving the project to the Johnson Space Center in 1994.

In the development of the VASIMR®engine, Ad Astra Rocket Company has collaborated with NASA Johnson Space Center, Oak Ridge National Laboratory, University of Texas at Austin, University of Houston and various other government space and research centers, industrial companies and academic organizations, including foreign universities.

VASIMR®

The VAriable Specific Impulse Magnetoplasma Rocket (VASIMR®) is a new type of electric thruster with many unique advantages. In a VASIMR®, gas such as argon, xenon, or hydrogen is injected into a tube surrounded by a magnet and a series of two radio wave (RF) antennas (called “couplers” in this context). The couplers turn cold gas into superheated plasma and the expanding magnetic field at the end of the rocket (the magnetic nozzle) converts the plasma particles’ thermal motion into directed flow.

Principles of Operation

The primary purpose of the first RF coupler is to convert gas into plasma by ionizing it, or knocking an electron loose from each gas atom. It is known as the helicon section, because its coupler is shaped in such a way that it can ionize gas by launching helical waves through the gas. Helicon antennae are a common method of generating plasma. See the Further Reading section for more about helicons.

After the helicon section, the gas is now a “cold plasma”, even though its temperature approaches that of the surface of the Sun. The soup of electrons and the atoms they were stripped from (ions) is primed for acceleration in the second stage. Where there were neutral gas atoms, there are now ions and electrons, which are charged, and such moving charged particles interact with magnetic fields. The magnetic field can be visualized as lines passing through the rocket with ions orbiting around each line.

The second RF coupler is called the Ion Cyclotron Heating (ICH) section. ICH is a technique used in fusion experiments to heat plasma to temperatures on the order of those in the Sun’s core. The radio waves hit ions and electrons along their orbits around field lines at resonance, similar to a person pushing another on a swing, resulting in accelerated motion and higher temperature. The VASIMR® ICH section produces plasma hotter than one million degrees Kelvin, or two hundred times the temperature of the Sun’s surface.

Thermal motion of ions around field lines is mostly perpendicular to the rocket’s direction of travel, however, and can’t help its propulsion. The rocket is dependent on its magnetic nozzle to convert the ions orbital momentum into useful linear momentum. As the magnetic field lines expand, the spiral paths of the ions around their field lines elongate, resulting in ion speeds on the order of 100,000 mph (50,000 m/s).

This material is copyright of Ad Astra Rocket Company (AARC)

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