Microwave thermal thruster PhD thesis now online!

Kevin Parkin · Posted on: Mon Jun 26, 2006 8:37 am

Quote:

"Nuclear thermal thrusters long ago bypassed the 50-year-old specific impulse (Isp) limitation of conventional thrusters, using nuclear powered heat exchangers in place of conventional combustion to heat a hydrogen propellant. These heat exchanger thrusters experimentally achieved an Isp of 825 seconds, but with a thrust-to-weight ratio (T/W) of less than ten they have thus far been too heavy to propel rockets into orbit.

This thesis proposes a new idea to achieve both high Isp and high T/W: The Microwave Thermal Thruster. This thruster covers the underside of a rocket aeroshell with a lightweight microwave absorbent heat exchange layer that may double as a re-entry heat shield. By illuminating the layer with microwaves directed from a ground-based phased array, an Isp of 700â€“900 seconds and T/W of 50â€“150 is possible using a hydrogen propellant. The single propellant simplifies vehicle design, and the high Isp increases payload fraction and structural margins. These factors combined could have a profound effect on the economics of building and reusing rockets.

A laboratory-scale microwave thermal heat exchanger is constructed using a single channel in a cylindrical microwave resonant cavity, and new type of coupled electromagnetic-conduction-convection model is developed to simulate it. The resonant cavity approach to small-scale testing reveals several drawbacks, including an unexpected oscillatory behavior. Stable operation of the laboratory-scale thruster is nevertheless successful, and the simulations are consistent with the experimental results.

In addition to proposing a new type of propulsion and demonstrating it, this thesis provides three other principal contributions: The first is a new perspective on the launch problem, placing it in a wider economic context. The second is a new type of ascent trajectory that significantly reduces the diameter, and hence cost, of the ground-based phased array. The third is an eclectic collection of data, techniques, and ideas that constitute a Microwave Thermal Rocket as it is presently conceived, in turn selecting and motivating the particular experimental and computational analyses undertaken."

..........................Download Thesis..........................

..........................Download Video..........................

..........................Download Charts..........................

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Author	Message
Kevin Parkin Launch Director Joined: Mon Dec 05, 2005 4:39 am Posts: 12 Location: Pasadena, CA, USA	Microwave thermal thruster PhD thesis now online! Posted on: Mon Jun 26, 2006 8:37 am Quote: "Nuclear thermal thrusters long ago bypassed the 50-year-old specific impulse (Isp) limitation of conventional thrusters, using nuclear powered heat exchangers in place of conventional combustion to heat a hydrogen propellant. These heat exchanger thrusters experimentally achieved an Isp of 825 seconds, but with a thrust-to-weight ratio (T/W) of less than ten they have thus far been too heavy to propel rockets into orbit. This thesis proposes a new idea to achieve both high Isp and high T/W: The Microwave Thermal Thruster. This thruster covers the underside of a rocket aeroshell with a lightweight microwave absorbent heat exchange layer that may double as a re-entry heat shield. By illuminating the layer with microwaves directed from a ground-based phased array, an Isp of 700â€“900 seconds and T/W of 50â€“150 is possible using a hydrogen propellant. The single propellant simplifies vehicle design, and the high Isp increases payload fraction and structural margins. These factors combined could have a profound effect on the economics of building and reusing rockets. A laboratory-scale microwave thermal heat exchanger is constructed using a single channel in a cylindrical microwave resonant cavity, and new type of coupled electromagnetic-conduction-convection model is developed to simulate it. The resonant cavity approach to small-scale testing reveals several drawbacks, including an unexpected oscillatory behavior. Stable operation of the laboratory-scale thruster is nevertheless successful, and the simulations are consistent with the experimental results. In addition to proposing a new type of propulsion and demonstrating it, this thesis provides three other principal contributions: The first is a new perspective on the launch problem, placing it in a wider economic context. The second is a new type of ascent trajectory that significantly reduces the diameter, and hence cost, of the ground-based phased array. The third is an eclectic collection of data, techniques, and ideas that constitute a Microwave Thermal Rocket as it is presently conceived, in turn selecting and motivating the particular experimental and computational analyses undertaken." ..........................Download Thesis.......................... ..........................Download Video.......................... ..........................Download Charts.......................... .
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spacecowboy Moon Mission Member Joined: Tue Feb 10, 2004 2:56 am Posts: 1104 Location: Georgia Tech, Atlanta, GA	Posted on: Mon Jun 26, 2006 3:20 pm cheers Congratulations! I'm gonna download all of it as soon as I get back on the Tech campus (at home with a measly 56k connection right now). Again, congratulations on successfully completing the dissertation and its defense. Good luck after graduation -- mind if I ask what your future plans are? _________________ American Institute of Aeronautics and Astronautics Daniel Guggenheim School of Aerospace Engineering In Memoriam... Apollo I - Soyuz I - Soyuz XI - STS-51L - STS-107
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publiusr Space Station Commander Joined: Wed Mar 09, 2005 1:25 am Posts: 887	Posted on: Fri Jun 30, 2006 7:55 pm I wonder if a ion-lifter type airship could also use its grid as a rectenna for beamed energy propulsion--with some combustable gases also giving thrust for ATO. Could a separate ground based beam charge the exhaust one way--and the nozzle the other--to increase specific impulse?
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Sigma Space Station Member Joined: Mon Dec 12, 2011 6:40 am Posts: 371 Location: California and Michigan	Re: Microwave thermal thruster PhD thesis now online! Posted on: Tue Nov 27, 2012 10:53 am What about a plasma supercavity? Accelerated via microwaves pushing the plasma envelope? _________________ Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.
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