Status of the magnetized cross beam energy transfer (MagCBET) campaign*

In laser-driven magneto-inertial fusion concepts, laser-plasma interactions occur in a magnetized environment.  In addition to changing plasma conditions, magnetization also changes laser polarization and propagation, as well as nonlinear plasma responses.  The MagCBET campaign at the OMEGA facility aims to measure the effects of magnetization on cross beam energy transfer (CBET), which controls the coupling and symmetry of implosions. Two shot days have been conducted using two configurations. (1) In the gas-MIFEDS configuration, a laser-heated gas jet provides a plasma target, which is magnetized using MIFEDS coils that provide ~20 T fields. After heater beams are turned off, a single OMEGA-60 beam is used as a CBET pump, and the wavelength tunable TOP9 beam is used as a CBET probe. Preliminary data suggests that magnetization decreases CBET at fixed laser drives, which is expected from the combined effects of increasing plasma temperature and decreasing nonlinear coupling. (2) In the foil-coil geometry, a laser heated carbon foil produces a plasma plume, and a laser driven coil produces a ~100 T magnetic field. In this configuration, two OMEGA-60 beams of equal wavelength are used as the CBET pump and probe. Resonance is achieved by unequal Doppler shifts in the plasma flow. Preliminary data suggests that turbulent magnetized jets are formed, in which CBET is observed. The stronger magnetic field in this configuration may enable observation of magnetized resonances away from the usual acoustic resonance.