Formation of Hot, Stable, Long-Lived Field-Reversed Configuration Plasmas on the C-2W Device
Abstract
TAE Technologies’ research is devoted to producing high temperature, stable, long-lived field-reversed
configuration (FRC) plasmas by neutral-beam injection (NBI) and edge biasing/control. The newly constructed C-2W
experimental device (also called “Norman”) is the world’s largest compact-toroid (CT) device, which has several key
upgrades from the preceding C-2U device such as higher input power and longer pulse duration of the NBI system as well as
installation of inner divertors with upgraded electrode biasing systems. Initial C-2W experiments have successfully
demonstrated a robust FRC formation and its translation into the confinement vessel through the newly installed inner
divertor with adequate guide magnetic field. They also produced dramatically improved initial FRC states with higher
plasma temperatures (Te ~250+ eV; total electron and ion temperature >1.5 keV, based on pressure balance) and more
trapped flux (up to ~15 mWb, based on rigid-rotor model) inside the FRC immediately after the merger of collided two CTs
in the confinement section. As for effective edge control on FRC stabilization, a number of edge biasing schemes have been
tried via open field-lines, in which concentric electrodes located in both inner and outer divertors as well as end-on plasma
guns are electrically biased independently. As a result of effective outer-divertor electrode biasing alone, FRC plasma is well
stabilized and diamagnetism duration has reached up to ~9 ms which is equivalent to C-2U plasma duration. Magnetic field
flaring/expansion in both inner and outer divertors plays an important role in creating a thermal insulation on open field-lines
to reduce a loss rate of electrons, which leads to improvement of the edge and core FRC confinement properties.
Experimental campaign with inner-divertor magnetic-field flaring has just commenced and early result indicates that electron
temperature of the merged FRC stays relatively high and increases for a short period of time, presumably by NBI and ExB
heating.
configuration (FRC) plasmas by neutral-beam injection (NBI) and edge biasing/control. The newly constructed C-2W
experimental device (also called “Norman”) is the world’s largest compact-toroid (CT) device, which has several key
upgrades from the preceding C-2U device such as higher input power and longer pulse duration of the NBI system as well as
installation of inner divertors with upgraded electrode biasing systems. Initial C-2W experiments have successfully
demonstrated a robust FRC formation and its translation into the confinement vessel through the newly installed inner
divertor with adequate guide magnetic field. They also produced dramatically improved initial FRC states with higher
plasma temperatures (Te ~250+ eV; total electron and ion temperature >1.5 keV, based on pressure balance) and more
trapped flux (up to ~15 mWb, based on rigid-rotor model) inside the FRC immediately after the merger of collided two CTs
in the confinement section. As for effective edge control on FRC stabilization, a number of edge biasing schemes have been
tried via open field-lines, in which concentric electrodes located in both inner and outer divertors as well as end-on plasma
guns are electrically biased independently. As a result of effective outer-divertor electrode biasing alone, FRC plasma is well
stabilized and diamagnetism duration has reached up to ~9 ms which is equivalent to C-2U plasma duration. Magnetic field
flaring/expansion in both inner and outer divertors plays an important role in creating a thermal insulation on open field-lines
to reduce a loss rate of electrons, which leads to improvement of the edge and core FRC confinement properties.
Experimental campaign with inner-divertor magnetic-field flaring has just commenced and early result indicates that electron
temperature of the merged FRC stays relatively high and increases for a short period of time, presumably by NBI and ExB
heating.
Research Areas
