Thursday, May 9, 2019
Experiments on the C-2U machine at TAE Technologies, a beam-driven field-reversed configuration (FRC) plasma, revealed an enhanced fusion rate above the expected thermonuclear level correlated with the presence of ion-cyclotron waves. This work surveys beam-driven ion-cyclotron instabilities in the scrape-off-layer (SOL) of the C-2U FRC and identifies beam-driven ion-Bernstein modes to be the likely cause of this fusion enhancement. This mode gives rise to large-amplitude ionic waves at ion-cyclotron frequencies while exhibiting the physics of wakefields saturated at the Tajima-Dawson field and generates a large fast-ion tail sufficient to yield fusion enhancement. The fusion enhancement is also shown to scale with beam energy according to a power law over a wide range of beam energies.