Laser style orion drives

[Charles Gray]

I have read in a few areas that one possible varient of the orion concept was to use lasers to fuse a hydrogen pellet in a combustion chamber and use the resultant exhaust to drive the ship--but haven't been able to find much in the way of information about it. Has anyone any links or other sources of information I could get about that form of propulsion?

 

[Lauge]

It sounds suspiciously like the inertial confinement fusion system used in the "Daedalus" interstellar probe designed by the British Interplanetary Society. See e.g.:

http://www.daviddarling.info/encyclopedia/D/Daedalus.html

or

http://www.bisbos.com/rocketscience/spacecraft/daedalus/daedalus.html

Daedalus used electron beams rather than lasers, though.

Regards & all,

Thomas L. Nielsen
Luxembourg

 

[elmayerle]

Well, it's appeared in some sf stories and has been written about in articles appearing in sf magazines. ISTR that sf editor Jim Baen was one of the first to suggest it to Jerry Pournelle (who I know has used it in at least one story) and other writers. In the real world? I'm not sure just what's been researched there.

 

[ouroboros]

Oddly enough I recently read a blurb about a paper to be released at a conference shortly on a nuclear lasing chamber concept, essentially directly coupling the nuclear reaction and the neutrons produced to the lasing cavity gases. Skips the electrical conversion process entirely. In some ways similar to the nuclear lightbulb drive concept. I suppose you could take it a few steps further, using liquid hydrogen fuel to cool a superconductor driven magnetic thrust chamber, cycle the gasified but cold hydrogen through the reactor to get the thermal energy recovery and cool the reactor, then pump the hot hydrogen into the thrust chamber to feed the fusion plasma being augmented/generated by the laser, then dump overboard via a magnetic nozzle like the one suggested for a VASIMR drive. Actually, what I just described would be almost like swapping out the helicon in a VASIMR drive for a laser. And if you really wanted to go for broke, use a LANTRN style oxygen afterburner to increase raw thrust via LOx dumping in the nozzle, if you were assuming the case of even amounts of LOx and LH2 being available from orbital propellant depots electrolyzing cargo water...

Um, I think this is the paper;

SPESIF Conference
http://ias-spes.org/SPESIF.html

Nuclear Pumped Lasers for Space Power Beaming Revisited
George H. Miley

Abstract. Power beaming by lasers is recognized as a key technology needed to support future space exploration. Important potential applications include beaming power from a terrestrial station to satellites or from a satellite station to remote sites on the lunar surface, Mars, etc. or to a propulsion unit. The best approach to power beaming is still under debate. However, Free Electron Lasers (FELs) and microwave generators have been proposed as alternatives to conventional lasers. In this paper, another uniquely different approach to power beaming, namely a Nuclear-Pumped Laser (NPL) is discussed.

The NPL uses neutrons from a fission reactor to excite ("pump") a gas by creating nuclear reactions in the gaseous laser medium. Since an energy source capable of high power levels is essential for any power beaming approach, the use of a fission reactor would be a common feature for multi-kW power beaming concepts. However, with an NPL, the direct neutron coupling of the reactor to the laser eliminates the need for a thermal to electrical conversion cycle, significantly increasing the overall system efficiency. Further, without a conversion sub-system, the overall system weight and volume is reduced and the unit is simplified. For land based units where weight is not crucial, a thermal conversion system can be retained to produce commercial electrical power simultaneously with the NPL power beaming operation. In this presentation we consider a specific NPL operating at visible wavelengths using a He-Ne-H2 laser medium which appears to be especially attractive for power beaming. Issues related to beam extraction and beam quality are discussed. A new technique using combined volume-surface pumping to control the beam profile is presented.