Launch | Cooling the light beamer

The most challenging element in terms of cooling the laser array system would be the small optical instruments in front of the primary mirror. This would be addressed with conventional cooling systems and possibly by cooling the beam director assemblies (lens assemblies).

The Alpha Centauri mission would require a 100GW-scale laser array. Traditional lasers are currently approaching 50% efficiency ratings. It seems likely that they will continue to improve in cost, power density and efficiency. Even given these improvements, it will be necessary to cool several tens of gigawatts for the laser and the beam director. However, since the lasers are distributed over the kilometer-scale array, this level of cooling is considered achievable.

Research:

Comments (8)

  1. michael.million@sky.com:

    The most likely cooling medium will be hydrogen as it has a large heat capacity, they currently use them effectively on turbine generator sets.

  2. Breakthrough Initiatives :

    Excellent question, michael.million@sky.com.

    As for cooling, the laser amplifiers are cooled with room temperature water or glycol coolant flowing through a heat exchanger in each amplifier. These heat exchangers are relatively simple and similar to the liquid heat exchanger sold for personal computers. The Sharshot system is only operational for about 100-300 seconds per launch and one option is to simply use a phase change material so no heat exchanger is needed. This is an option we are exploring.

    – Prof. Philip Lubin, Breakthrough Starshot

  3. michael.million@sky.com:

    'Jul 23, 2016 21:22 Breakthrough Initiatives Posted on: Breakthrough Initiatives

    Excellent question, michael.million@sky.com.

    As for cooling, the laser amplifiers are cooled with room temperature water or glycol coolant flowing through a heat exchanger in each amplifier. These heat exchangers are relatively simple and similar to the liquid heat exchanger sold for personal computers. The Sharshot system is only operational for about 100-300 seconds per launch and one option is to simply use a phase change material so no heat exchanger is needed. This is an option we are exploring.

    – Prof. Philip Lubin, Breakthrough Starshot'

    Hydrogen can not only be used to cool and make a MHD generator more powerful but the hot hydrogen can also be used in a fuel cell to generate power.

  4. Allen Hall:

    hydrogen is very expensive and hard to store besides being an explosion hazard. The cost of hydrogen is many times the cost of the equivalent energy off the grid. It isnt likely going to be an advantage over air or liquid cooling in this environment. The challenge is at 50% efficiency, which is unlikely to improve, you have 3 kilotons of heat to dissipate in a 120 second run... kilometer or not that heat load is daunting.

  5. michael.million@sky.com:

    "hydrogen is very expensive and hard to store besides being an explosion hazard. The cost of hydrogen is many times the cost of the equivalent energy off the grid. It isnt likely going to be an advantage over air or liquid cooling in this environment. The challenge is at 50% efficiency, which is unlikely to improve, you have 3 kilotons of heat to dissipate in a 120 second run... kilometer or not that heat load is daunting."

    Hydrogen can remove heat which can then be used in a fuel cell to drive other equipment such as circulatory cooling systems, it could be a hybrid liquid water/ hydrogen system. Using hydrogen improves the efficiency of the system instead of it been dissipating it into the atmosphere.

  6. Breakthrough Initiatives:

    RE:
    "Jul 25, 2016 10:58 michael.million@sky.com Posted on: Centauri Dreams

    Hydrogen can not only be used to cool and make a MHD generator more powerful but the hot hydrogen can also be used in a fuel cell to generate power."

    Answer:
    We would very much like to use an MHD generator. At this time they are not available.

    - Avi Loeb, Breakthrough Starshot

  7. Richard C:

    Hi all, I'm reading this interactively as I'm quite late to this thread. I've read the comments and would like to ask something based on the commentary so far. Recently a group at UC Boulder has found a way to use meta materials to cool air with no energy input needed. I'm not suggesting this solution over the proposed solution, however, could this be considered for part of the cooling system? I imagine these technologies all have low TRLs but advancing their TRL level in a timely way would be a key consideration. Link to journal article: http://science.sciencemag.org/content/early/2017/02/08/science.aai7899

  8. Breakthrough Initiatives:

    RE:
    "Feb 14, 2017 20:46 Richard C Posted on: Breakthrough Initiatives"

    Answer:
    These are truly exciting materials. I think it could dramatically change the way we heat and cool our buildings. I wonder how they hold up to the weather. We are investigating various types of perfect reflectors and this class of meta material is a leading candidate for our sail material. If we can get the material mass down. Currently it is about 5 times to heavy. We also have concerns about it ability to withstand the shock loads required.

    - Pete Klupar, Breakthrough Starshot

Please sign in to be able to add new comments.