Here, an engineering upgrade to the neutral beam system at the DIII-D tokamak enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic (E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities andmore »
DOE PAGES offers free public access to the best available full-text version of DOE-affiliated accepted manuscripts or articles after an administrative interval of 12 months. The portal and search engine employ a hybrid model of both centralized and distributed content, with PAGES maintaining a permanent archive of all full text and metadata.