The Pegasus Toroidal Experiment has focused on exploring the unique features of extremely low aspect ratio operation to study plasma stability at A ~ 1 and near-unity beta, including access to ohmic H-mode with associated ELM behavior and plasmas with an absolute minimum-B topology. For such studies, the Local Helicity Injection (LHI) technique was developed to initiate and drive toroidal...
Identifying attractive means of initiating current without using induction from a central solenoid remains a critical challenge facing the spherical tokamak (ST) concept, and is desirable for tokamaks in general. An electron Bernstein wave (EBW) heating and current drive system is being designed for use in overdense ST plasmas on the upgraded Pegasus Toroidal Experiment. The research program...
The spherical tokamak (ST) may require and the advanced tokamak would considerably benefit from the elimination of the central solenoid. PEGASUS-3 is a ST non-solenoidal startup development station under design and fabrication dedicated to solving the startup problem. On PEGASUS-3, Transient and Sustained coaxial helicity injection (T- and S-CHI) will be explored, as well as possible synergies...
Described are first results obtained on the Globus-M2 tokamak – upgraded version of Globus-M machine in spring-summer 2019 operating campaign. Operation was performed at toroidal magnetic field strength 0.7 T and plasma current 0.3 MA. Results of the campaign may be tentatively joined into a few groups. First group is related to initial stage of the discharge. Plasma breakdown conditions were...
The presentation is devoted to the thermal energy confinement study at the compact spherical tokamaks Globus-M and Globus-M2. Experiments were performed under auxiliary heating using neutral beam injection (NBI) in plasma with lower null magnetic configuration (major radius R = 0.35 m, minor radius a = 0.21-0.22, elongation ~1.9, triangularity δ~0.35) for the ranges of plasma current and...
