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Photonic Laser Thruster

  1. Sep 11, 2007 #1
    DARPA, NASA, JPL and various aerospace giants are rushing to learn more about a massless thruster developed by Dr Young Bae:

    http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=201804852

    http://www.photonics.com/content/news/2007/September/7/88894.aspx

    At the claimed millinewtons of thrust, it may be applicable for orbital maneuvering. However, the claim is also being made that it could be scaled up to deliver kilonewtons of thrust, given enough power (from a nuclear reactor, for example)

    Wow, that would be pretty amazing, not to have to carry propellant mass with you. But I wonder how efficient the power coupling/conversion is? What are the limitations on how far it can be scaled up? Are kilonewtons really possible?

    And of course, is this phenomenon really legitimate?
    I'd really like to hear comments/feedback.
     
  2. jcsd
  3. Sep 6, 2010 #2
    can't we use this photonic laser thruster in vehicles... i mean cant you build a car working on this concept?
     
  4. Sep 6, 2010 #3
    The propellant mass is nuclear fuel (last sentence of the eet article) Now that's a limitation (reactors are heavy and radioactive).
     
  5. Sep 7, 2010 #4
    If you don't mind being restricted to moving along a perfectly straight line, clear of obstacles and without anything to jostle the vehicle and interfere with alignment with the multi-gigawatt laser pointed at you. If this is so, then yes, you could build a car working on this concept.

    This is essentially just a laser sail craft, with additional optics that bounce the light back at the "sail" so it reflects off multiple times. The multiple reflections within the cavity formed by the emitter and payload do increase the outward thrust on both. Alignment has to be very precisely maintained as the payload moves away, and the size and precision requirements of the reflecting elements will limit the distance at which this works...diffraction limits require large optics, large and high precision optics will tend to be heavy, large and lightweight optics won't be precise enough to manage multiple bounces. A plain old light sail might work better, due to being a bigger target that can be hit at longer range, while being far lower mass. Acceleration will be lower, but can be kept up for a longer time.

    The power source is nuclear and nuclear reactors are heavy, but the power source is essentially stationary. Mass on the laser end just reduces the recoil accelerations and lets you go longer between corrections to the launch platform's orbit. Those corrections do require propellant, but the launch platform doesn't go anywhere, it stays put where it can easily be reached for propellant resupply.
     
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