Mechanical design of the ICRH antenna for JET-EP

The JET-EP antenna is designed to verify the design principles of that proposed for ITER, in relevant plasma conditions. It is intended to launch 7.2 MW of RF power to the plasma of the JET machine during its 'Enhanced Performance' program, at a power density of around 8 MW/m/sup 2/. The antenna comprises two poloidal current straps, each subdivided into four electrically short straps complete with in-vessel capacitors. The antenna is supported via a cantilever support box to the external support structure. This plug-in, through-port type assembly is clamped to the vacuum vessel externally. The antenna itself is fitted remotely. External rails and bellows allow radial positioning of the assembly. Eight capacitors are situated just behind the short antenna current straps. Plug-in replacement of the capacitors is performed through the vacuum vessel port.