The hardware and diagnostic configuration of MRX for the FRC sustainment experiments.
The poloidal flux (contours) and toroidal field (colors) for sustained (top row) and unsustained (bottom row) argon FRCs. Note the nonuniform timing of the figures.
False color images of FRC formation and sustainment, taken in white light using a fast visible camera.
Radial profiles of the axial magnetic field (top row), as measured by the spoke probes, and electron pressure (bottom row), as measured by radially scanning a Langmuir probe at the midplane. Results are shows for argon discharges with (closed symbols) and without (open symbols) inductive sustainment.
Scan over solenoid firing voltage with all other parameters (fill pressure, coil waveform shapes) held fixed. Shown are the (a) solenoid flux, (b) trapped poloidal flux, (c) toroidal flux, and (d) surface voltage. The short-lived plasma in frame (b) is a case without sustainment. The gray areas on the far left represent the time before merging is finished, and those near represent the time duration for the averages in Fig. 6.
Measured and derived plasma parameters as a function of solenoid firing voltage, for the argon FRC voltage scan in Fig. 5. The data are averaged over the period , and error bars represent shot-to-shot variability.
Profiles of the radial particle flux, as determined by the Ohm’s law analysis.
Time evolution of (a) the trapped poloidal flux and the solenoid flux, (b) the total thermal and magnetic energies, and (c) the terms in the Poynting’s theorem power balance analysis.
Poloidal flux, decay index , and midplane perturbations as a function of time, in argon plasmas sustained with different solenoid voltages.
(a) The trapped flux and solenoid flux, and (b)–(d) the nonaxisymmetric perturbations, for sustained and unsustained nitrogen discharges.
The maximum amplitude of , 2, 3, and 4 modes, normalized by the field at the separatrix immediately after merging, plotted against the FRC lifetime for a range of working gases.
Growth rates for the , 2, 3, and 4 axially polarized co-interchange modes, as a function of Lundquist number. The vertical lines show the typical Lundquist numbers of the different working gases.
Amplitude of the perturbations, as a function of the kinetic stability parameters , , 2, 3, and 4.
Typical range of parameters for FRCs in MRX. Some discharges lay outside the typical range specified here.
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