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The energy injector is like 4000 microwave ovens, another innovative design element of this reactor.

They use a process called radio-frequency heating to ignite the nuclear fuel. These antennae outside the tokamak reactor use a specific frequency of radio waves to excite the particles. The radio waves are calibrated to target just the less abundant material, in this case hydrogen ions. Because the hydrogen accounts for a small fraction of the fuel’s total density, focusing the radio-frequency heating on the minority ions allows them to reach extreme energy levels. The excited hydrogen ions then slam into the more abundant deuterium ions, and resulting particles fly into the reactor’s outer shell, generating heat and electricity.

And then… “Researchers improved the efficiency of this process by adding helium-3 ions to the mix. The new fuel contains less than one percent helium-3. By focusing all the radio-frequency heating on this trace amount of helium-3, the researchers raised the ions to megaelectronvolt (MeV) energies. An electronvolt is the amount of energy gained or lost when a single electron jumps from a point of electric potential to a point one volt higher, a common unit of measurement for fusion experiments. The new results with helium-3 fuel, generating ions that reach megaelectronvolt energies, has never been achieved before, and the increase in ion energy is a full order of magnitude higher than previous efforts.” — Popular Mechanics

4 responses to “Microwave Energy Injector for Commonwealth Fusion Systems”

  1. jurvetson Avatar
    jurvetson

    Looking down at it from the top of the reactor And today’s funding newsCONGRATS to Commonwealth Fusion Systems (CFS) on closing their $115M Series A round

    Reply
  2. sbove Avatar
    sbove

    For ref: "In the ITER Tokamak…an input heating power of 50 MW is required to bring the plasma to the temperature necessary for fusion." This energy is "transferred to the ions in the plasma by a high-intensity beam of electromagnetic radiation with a frequency of 40 to 55 MHz (in a process called ion cyclotron resonance heating (ICRH).

    In the Commonwealth system, similar radio frequencies are used (32.2-80 Mhz depending on the reactor Alcator/JET) but only 3.2 MW to 5 MW (also depending on reactor) are needed to bring the plasma to fusion temperatures (an order of magnitude less than in the Tokamak) due to low quantity Helium-3 ion doping of the plasma. The H-3 ions act like water does in foods in a microwave oven, efficiently resonating in the RF beam and transferring energy to the surrounding material.

    Note: 4 MW to 50 MW of RF power is huge!…For comparison a typical big city TV station broadcasts with 25 KW to 100 KW and the world record TV/Radio transmitting tower pumps out 2.5 MW.

    From the paper in Nature:

    http://www.nature.com/articles/nphys4167.epdf?author_access_toke...

    "A variety of strong wave–particle interactions is possible when the wave frequency is close to the particle’s cyclotron frequency or its harmonics. Ion cyclotron resonance heating (ICRH) is a powerful tool used in toroidal magnetic fusion research. In recent decades, several efficient ICRH scenarios were identified theoretically and verified experimentally. In brief, this technique relies on external excitation of fast magneto sonic waves in the plasma, using specially designed ICRH antennas located at the edge of the device (see Fig. 1a). Antennas consist of a series of metallic straps that carry radio-frequency (RF) currents at a given frequency delivered by an external generator. The radially varying toroidal magnetic field then determines the location of the ion cyclotron layers ω = pωci(p = 1, 2, . . .), in the vicinity of which the RF power can be efficiently absorbed by ions."

    Cool vid Alcator C-Mod 360 degree tour > http://www.youtube.com/watch?time_continue=1&v=nkMM61e8Ajw

    Reply
  3. sbove Avatar
    sbove

    ps: this is an insanely awesome and daring investment! I was once a delegate to the Harvard Model United Nations (in high school) and won a best delegate award for advocating fusion as an important emerging technology in the Economic and Social Committee sessions. No one knew what the hell I was talking about. 😉

    Reply
  4. jurvetson Avatar
    jurvetson

    thanks! It is incredibly exciting.

    Reply

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