STM-D-0582Paper2023On the bench now

The Princeton Field-Reversed Configuration for Compact Nuclear Fusion Power Plants

Christopher Galea · Stephanie Thomas · Michael Paluszek · Samuel Cohen

Abstract and summary · read the original at the source

In one page

Fusion reactors are usually imagined as buildings. Christopher Galea, Stephanie Thomas and Michael Paluszek of Princeton Fusion Systems, with Samuel Cohen of the Princeton Plasma Physics Laboratory, describe one you could put on a truck. The Princeton Field-Reversed Configuration holds its plasma inside a ring of closed magnetic field lines that the plasma largely makes for itself, in a tube four to eight metres long and a metre and a half across, and heats it with a single radio-frequency trick: an odd-parity rotating magnetic field, which their modelling says keeps those field lines closed instead of letting the plasma leak out along open ones. The fuel is deuterium and helium-3, which returns its energy mostly as charged particles rather than neutrons, so the design aims for about a thousand times less neutron loading on the wall than a deuterium-tritium tokamak. Two machines already exist. PFRC-2 has heated electrons past 500 electronvolts and held plasmas for 300 milliseconds, and the paper names exactly what the next two machines have to reach.

Why it matters hereChapter 12 argues that every scheme in this book needs the same thing first — a small source of very large energy — and the PFRC is the compact, aneutronic-leaning, hardware-in-the-lab version of that requirement. It also belongs to chapter 9, because a field-reversed configuration is a self-organising plasma structure holding its own closed field lines, the same physics family as the plasmoid.

What it claims

01An odd-parity rotating magnetic field, RMFo, drives current, heats the plasma, improves confinement and provides stability with a single radio-frequency system, and unlike the even-parity picture-frame antennas used before it, it maintains a field-reversed configuration with closed magnetic field lines rather than open ones that let the plasma escape — first theorised in 2000, since reproduced by an analytical model and by particle-in-cell simulation.Section 1, Introduction; Section 2.2, RMFo Heating Method
Published and peer-reviewed
02In the second-generation PFRC-2 experiment, with an 8 centimetre flux-conserver radius, minority electron populations have reached temperatures of 500 electronvolts and maximum energies above 1.5 kiloelectronvolts, with pulse lengths up to 300 milliseconds — more than 10⁴ times longer than the predicted growth time of the tilt instability — at radio frequencies from 4.3 to 12 megahertz, forward power to 100 kilowatts and coupling efficiency to the plasma of 60 percent.Abstract; Section 3, Status of Development, and Table 1
Published and peer-reviewed
03Scaled to fusion parameters, a PFRC power reactor would be 4 to 8 metres long and 1.5 metres in diameter and produce 1 to 10 megawatts of fusion power, making it suitable for submarines, urban sites and space propulsion.Abstract; Section 2, Overview of the PFRC Reactor Concept
Designed, not yet built
04Burning deuterium and helium-3 in a high-beta configuration, where beta is plasma pressure over magnetic-field energy density, gives about 1000 times lower neutron power flux on the inner wall than a deuterium-tritium tokamak, because the main reaction produces no damaging neutrons and the machine is small enough to exhaust the tritium made by deuterium-deuterium side reactions before it burns.Section 2.3, Power Flow and Neutron Loads, Equations 1 to 3
Designed, not yet built
05A one-dimensional power-flow model of a 2 megawatt thermal reactor, drawing 0.79 megawatts of rotating-magnetic-field power produced at better than 90 percent amplifier efficiency and converting heat through a 50 percent efficient Brayton cycle, returns 0.57 megawatts of net electric power.Section 2.3, Figure 7
Designed, not yet built
06The step that decides the concept is energy confinement near classical at reactor scale: PFRC-2 is being upgraded to a 2 megahertz rotating field at up to 200 kilowatts, where single-particle simulations predict explosive ion heating above 1 kiloelectronvolt, and PFRC-3 must then reach 1.5 tesla, 10 kiloelectronvolt ions and a one-second pulse — with a new supply of helium-3, from natural gas, CANDU reactors, breeding or lunar mining, needed before widespread use.Section 3, Table 1; Section 5, Summary and Next Steps
What to watch

Read it · abstract

Abstract

The Princeton Field-Reversed Configuration (PFRC) nuclear fusion reactor concept is an innovative approach to fusion power generation prioritizing low neutron production and small size. A combination of analytical modeling and numerical simulation shows that the novel heating approach generates an FRC with closed field lines. Simulation data from a single-particle Hamiltonian code predicts ms-scale plasma heating in reactor-scale conditions while PIC codes predict formation of warm FRC plasmas from initial mirror fields. The PFRC-1 and PFRC-2 experiments have heated electrons to energies well in excess of 100 eV and plasma durations to 300 ms, more than 10⁴ times longer than the predicted tilt instability growth time. From these data, we have created a development plan and anticipated performance metrics for a fusion reactor based on the PFRC concept. The resulting 1-10 MW PFRC reactors would be suitable for diverse applications, from submarines to urban environments to space propulsion. PFRC is a steady-state, driven magnetic confinement device. Plasma, inside a cylindrical array of coils, is confined and heated by external RF antennae. PFRC would be ultra-low radiation due to both its fuel and small size. The choice of advanced fuels, deuterium and helium-3 (D–³He), may be enabled by the high-β FRC configuration. The small size of the reactor would enable rapid exhaust of the dangerous tritium ash. Low radiation would make the reactor safer to operate and, in combination with simple geometry and small size, dramatically lowers development and maintenance costs. This review paper gives an introduction to the physics of the PFRC and a summary of the PFRC-2 experiment results to date. It then discusses the future program plan and how PFRC reactors would be commercialized.

The way in

https://doi.org/10.1007/s10894-023-00342-2Published in the Journal of Fusion Energy in 2023. The accepted manuscript is free to read as a green open-access deposit at the US Department of Energy’s OSTI repository, but neither that deposit nor the publisher page carries a Creative Commons statement — Springer’s terms cover text and data mining only — so this page carries the summary, the claims and the authors’ own abstract and sends the reader to the source. The work was supported by ARPA-E grant DE-AR0001099, a NASA Innovative Advanced Concepts grant and two NASA STTRs.

How to cite it

Christopher Galea, Stephanie Thomas, Michael Paluszek, Samuel Cohen (2023) The Princeton Field-Reversed Configuration for Compact Nuclear Fusion Power Plants. doi:10.1007/s10894-023-00342-2

Where it sits in the curriculum

Lattice confinement fusion Plasmoids, charge clusters and the orbs