Conceptual design of the vacuum, fueling, and instrumentation and control systems for the IGNITEX experiment

Present physics scaling laws indicate that the proposed ignition experiment IGNITEX should reach ignition with ohmic heating alone. A conceptual design of the vacuum, fueling, and instrumentation and control systems for the experiment is presented. The vacuum vessel will have an internal surface area of about 40 m² with 50 small (10-cm) ports and two larger (24-cm by 24-cm) ports for diagnostic and maintenance access. The primary pumping for the system will be done by a set of four turbomolecular pumps through the square ports. An additional set of redundant turbo pumps will also be present to allow continued operation in the event of pump failure. In order to achieve the base pressure of 10^-8 torr required for clean plasmas, the vacuum vessel will be heated by passing current through the magnet system for bakeout. Discharge cleaning will provide day-to-day conditioning of the vessel. Two approaches for fueling are under consideration. The first is gas puffing, which offers the advantage of simplicity but may not achieve the peaked density profiles desirable for improved confinement. The second is pellet injection. However, injection of a pellet into the center of the high-density, high-temperature plasmas expected in an ignition experiment may require pellet velocities beyond those presently available. The instrumentation and control systems consist of various subsystems. These include control of the power supplies, control of the diagnostics and data acquisition, and environmental analysis