Interior antenna for substrate processing chamber

1 21 2An antenna for coupling RF energy to a plasma in a process chamber having a wall comprises a coil having a face exposed to the plasma in the chamber. A plurality of standoffs support the coil at a set spacing from the wall of the process chamber, at least one standoff comprising a terminal thorough which electrical power is applied to the coil from an external power source. The terminal comprises a conductor receptacle having a first length Land a jacket around the conductor receptacle, the jacket having a second length L. The length Lis larger than the length L. A conductor cup is provided about the standoff having the terminal.