Scientific and Engineering Challenges and Future R&D Priorities for Pulsed-Power IFE Applications

Implosion of magnetized plasma inside a conducting cylinder on open field lines to achieve fusion ignition depends on magnetic inhibition of radial energy transport and effective fusion burn before the hot plasma can run out the ends. MagLIF would achieve this with a ~100 ns implosion time and a few centimeters of high-density plasma confined by open magnetic field lines. Thus, the major target physics challenges that are to be addressed in the near term on Z are the following:

  • Demonstrating that the predicted high-efficiency energy transfer from electrical energy to hot magnetized fusion fuel plasma compressed by magnetic-field-driven implosion of a cylindrical conducting liner occurs in experiments. Determining plasma conditions inside the imploding liner is a major part of this challenge.
  • Demonstrating that the energy-loss rate of the compressed plasma is much less than that of an unmagnetized plasma. Understanding how the magnetic field affects the transport coefficients is a necessary part of this research to allow validating the design codes.

The MTF version of the two items is to demonstrate at 6 MA that a sufficiently well-confined plasma can be produced to warrant explosively driven experiments that have a much higher cost than the pulsed-power experiments. As in MagLIF, diagnostic access to the plasma if it is not generating the predicted number of neutrons is very limited, again making determination of the plasma condition inside the liner a part of this challenge.

The biggest early technology challenge for pulsed-power IFE is establishing the technical credibility of the proposed low-repetition-rate (~0.1 Hz), ~10 GJ yield-per-pulse reactor concept. The recyclable transmission line approach for delivering the current from the pulsed-power system to the fusion-fuel-containing target must be demonstrated to be technically feasible. Technical issues that must be addressed for the transmission line include these: what material to use, how thick it must be, and how to recycle it economically; how best to load the assembly in the reactor chamber (bearing in mind that the fusion-fuel-containing load—possibly requiring cryogenics—must be attached to it); and how to assure that the assembly makes a good electrical connection to the pulsed-power system.

Demonstrating the engineering feasibility of a thick-liquid-wall reactor chamber is a challenge that pulsed-power shares with other possible approaches, particularly heavy-ion fusion. However, pulsed-power fusion, as most recently proposed, is alone in requiring compatibility of the reactor chamber with recyclable transmission lines and with ~10 GJ yield per pulse (the equivalent of 2.5 tons of high

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