Compact ignition experiments: design and performance

Compact high field experiments are shown to be suitable for producing low-temperature ignition (T₀≃11 keV) of D-T plasma mixtures with n₀≃10²¹ m^-3 under known criteria of both energetics and stability. The 12 MA plasma current considered for the Ignitor configuration is gradually induced in the plasma column while its cross section is increased, allowing the control of the current density distribution in such a way that the region where q⩽1 has a relatively small volume. This is done in order to avoid the onset of internal sawtooth oscillations that can prevent attaining ignition. The ohmic heating is maintained at relatively high levels up to ignition conditions, as the loop voltage retains a significant variation over the plasma radius. Since ignition can be attained by ohmic heating alone, injected heating systems in compact high field experiments should have the role of backups and be available, if needed, to suppress the possible onset of sawtooth oscillations, to control the temperature and the current density profiles, and to accelerate the attainment of ignition