Long Pulse Operation of the Centrifugal Mirror Fusion Experiment (CMFX)

The goal of CMFX is to investigate the stability and scalability of centrifugally confined plasmas for fusion energy production. An applied voltage across the magnetic field yields an azimuthal E x B drift with supersonic speeds that creates velocity shear that stabilizes and heats the plasma. A pair of superconducting magnets are used to produce 3 T mirror fields and 0.375 T at midplane. The cylindrical chamber with a length of 6.7 m and diameter of almost 0.8 m contains a high-voltage center electrode, tungsten-coated circular grounding limiters, and bucket-shaped insulators to allow for applied voltages of up to 100 kV. A hydrogen gas-puff system allows for discharges exceeding 200 ms with peak voltages of 20 kV and densities of order 10¹⁸-10¹⁹ m^-3 with momentum confinement times measured at 20 – 30 ms and higher. Ion Doppler spectroscopy, interferometric density diagnostics, and neutron detectors are now operational. Plans for x-ray diagnostics, Thomson scattering, and preliminary data from deuterium discharges at peak voltages of 50 kV are presented.