Light Beamer | Phase

In order to test the feasibility of the system, the case of a meter-scale sail was examined. For example, to focus the light beam on a 4mX4m sail across an acceleration distance of 2x106 km requires a focusing angle of 2 nano-radians (0.4 milliarcseconds), which is the diffraction limit for a kilometer-scale light beamer operating at a wavelength of 1 micron.

Interferometry with the Event Horizon Telescope has already been demonstrated across the Earth, achieving sub-nano-radian precision at a 1mm wavelength. This is an encouraging benchmark on the way to achieving the required precision of the optical system for a kilometer-scale array on the ground.

Comments (24)

  1. Breakthrough Initiatives:

    "Sep 01, 2016 14:54michael.million@sky.comPosted on: Centauri Dreams
    Perhaps if we had a number of FEL linacs/undulators arranged in a circle arrangement with a mirror at the end of each unit with a hole in it so electrons can make their way through to the next linac/undulator unit. The electrons can be kept in constant motion around the 'circle' reducing losses significantly as they don't need to be slowed down or stopped. Each mirror is then used to deflect the produced laser light upwards to propel the craft."

    "Sep 04, 2016 17:59michael.million@sky.comPosted on: Centauri Dreams
    We could build a test scalable FEL model of modest power built for a low price. 
    I am thinking of three linac/undulators arranged in a triangle with a mirror/prism near towards the apex with a hole in them. If we bend the electron beam with large magnets before each mirror and into the next linac/undulator system and so on we can improve the efficiency quite a bit by recycling the electrons. With the hole in the mirror/prisms we can use some of laser light as a seed via a reflection prism into the next linac/undulator unit and so on which would again aid the efficiency of the system. This test model could be built in the Nevada desert (mentioned earlier) where the altitude is high, but importantly it would have access to the power grid or at least some decent mobile electrical generators."

    These are good approaches that need to be investigated. FEL should certainly be considered, but keep in mind that we need over 50GW of laser light in the final system.

    - Avi Loeb, Breakthrough Starshot


    FEL lasers can certainly deliver that power in bursts, TW's even, since there is no medium to be heated they can be very powerful, they will need the electron re-cycling issue resolved though to be effective.

  3. Breakthrough Initiatives:

    "Nov 18, 2016 11:16 Posted on: Centauri Dreams

    FEL lasers can certainly deliver that power in bursts, TW's even, since there is no medium to be heated they can be very powerful, they will need the electron re-cycling issue resolved though to be effective."


    We intend to consider using electron recycling at least in the early portion of the thrusting phase of the flight.

    - Avi Loeb, Breakthrough Starshot


    We could have standard FEL modules installed over time, if say we had the FEL's arranged in a circle with the bending magnets in an articulated arrangement so the circle of FEL's just gets bigger by adding FEL units or can be arranged in smaller circles. This arrangement will improve the recyclability efficiency of the electrons enormously, just need to keep them going through the FEL's and they will only need to be dumped or decelerated at the end of a powered phase. This arrangement also allows us to stack the FEL beam systems so multi-channels can be used, i.e. the first top FEL's electrons are deflected into the next FEL by magnets and the laser light is reflected upward after going through a small channel. The next lower laser beam has a slightly longer channel with a mirror at the end of it and so on, each channel slightly further out. This arrangement allows us to share RF power circuits and/or drift tubes and magnet sets lowering the cost of the system significantly. We can start small and just get bigger over time but it also allow us to use small parts of the overall system as and when or the application requires.

Please sign in to be able to add new comments.