By Izentis LLC
Izentis was a contractor for the Millimeter-Wave Thermal Launch System (MTLS) program funded by NASA Ames and DARPA. This technology is similar to the Microwave Thermal Thruster proposed by Dr. Kevin Parkin. The idea is to use millimeter waves to heat a working fluid via an alumina or silicon carbide heat exchanger. Alumina and silicon carbide channels will strongly absorb millimeter waves with the right dopants and wall thicknesses. A fluid is then passed through the channels and convectively heated, and then expanded out a nozzle like a chemical rocket. The propellant can be chosen almost arbitrarily, which isan advantage of this approach. Hydrogen can be used, which has a specific heat capacity 5 to 10 times that of the product gases from typical chemical rockets. This could lead to exhaust velocities in excess of 8,000 m/s for temperatures around 2,500 K. The MTLS program was aimed at demonstrating the technology and it was broken down into two phases. The first was to test materials and coatings for the heat exchanger with a high-power gyrotron. The second phase was to use a 100 kW class W-band source to power a small test vehicle. The goal was to demonstrate a complete launch of a millimeter-wave powered rocket. Izentis entered the project to consult on phase 1 of the project, and then was contracted to build the test vehicles for phase 2. This included designing and building the high-pressure fluid systems, aerostructure, recovery system and radiation protection system. Izentis integrated the vehicles with the heat exchangers, and took part in the test flight campaigns. The high-pressure fluid systems were operated at 3,000 psi and met NASA safety standards for human handling. The program ended with the successful launch of a test vehicle demonstrating the feasibility of beamed energy propulsion via millimeter waves and heat exchangers.
