Magneto-Inertial Fusion Technologies, Inc.
Magneto-Inertial Fusion Technologies, Inc. (MIFTI) is a private company developing fusion in a Staged Z-pinch, c.f., illustration.[1] The SZP is one of several concepts studied in the context of magneto-inertial fusion and magnetized-target fusion, where a magnetically accelerated, imploding liner compresses a deuterium-tritium target.
Implosion of the liner occurs under the action of a magnetic force, produced when a large-electric current flows through a plasma column (pinch effect). The time required for the liner to collapse to the axis is typically shorter than a microsecond, when driven by a pulsed, high-current, high-power electrical supply. The Sandia National Laboratories Z Facility is probably the best example of a state-of-the-art, pulsed-power driver used for these types of studies [2]
As the liner collapses to the axis, the target is compressed and heated adiabatically, increasing the density and temperature of the fuel, to levels needed for fusion to occur. To insure that a high-fusion yield occurs, a sequence of dynamic processes must be precisely timed, based on design parameters for the pinch configuration. For example, the total mass of the system must be adjusted in order that the compression occur near the time of peak current, the initial diameter of the pinch must not be so large that it becomes uncontrollably unstable before reaching the axis, the initial thickness of the liner must be small enough that the pinch may obtain a mm final diameter, yet thick enough that the azimuthal-magnetic field does not simply penetrate through the liner before implosion occurs, etc.
Azimuthal- and axial-magnetic fields present in the liner and target initially, also affect the implosion dynamics, as they will compress during implosion,[3] rising potentially to levels of many kiloTesla, and more. The presence of such large magnetic fields isolate the fuel from the liner, reducing thermal losses; stabilize the implosion against the Rayleigh-Taylor Instability; confine charged particles produced during the fusion burn (i.e., alpha particles), as well as provide an additional source of heat energy to the target. If the alpha particle heating is sufficiently intense, it may also provide a pathway to ignition.[4] Moreover, the rapid time compression of these magnetic fields leads to sizeable induction currents, and additional pathways to couple energy into the target.[1]
Simulations suggest that pinch dynamics in the staged Z-pinch are distinct from other approaches. If the imploding liner is made of a high-atomic number material, i.e., one produced from a thin-silver foil, or an ionized-krypton gas, a shock is formed that that pre-heats the target ahead of the liner collapse.[5] Shock preheating raises the target adiabat, eliminating potentially the need for additional heat inputs and reducing the convergence ratio of the liner that is needed to achieve fusion temperatures.
References
- 1 2 Rahman, H. U.; Wessel, F. J.; Rostoker, N. (1995). "Phys. Rev. Lett. 74, 714 (1995) - Staged $Z$ Pinch". Physical Review Letters. doi.org. 74 (5): 714. Bibcode:1995PhRvL..74..714R. PMID 10058829. doi:10.1103/PhysRevLett.74.714. Retrieved 2017-05-10.
- ↑ "www.sandia.gov/z-machine/". sandia.gov. Retrieved 2017-05-10.
- ↑ Wessel, F. J.; Felber, F. S.; Wild, N. C.; Rahman, H. U.; Fisher, A.; Ruden, E. (1986). "Generation of high magnetic fields using a gas‐puff Z pinch". Applied Physics Letters. 48 (17): 1119. Bibcode:1986ApPhL..48.1119W. doi:10.1063/1.96616.
- ↑ "Fusion in a Staged Z-pinch". ieeexplore.ieee.org. Retrieved 2017-05-10.
- ↑ Narkis, J.; Rahman, H. U.; Ney, P.; Desjarlais, M. P.; Wessel, F. J.; Conti, F.; Valenzuela, J. C.; Beg, F. N. (2016). "Shock formation in Ne, Ar, Kr, and Xe on deuterium gas puff implosions". Physics of Plasmas. 23 (12): 122706. doi:10.1063/1.4972547.