An inductively coupled plasma ion source for a focused ion beam (FIB) system is disclosed, comprising an insulating plasma chamber with a feed gas delivery system, a compact radio frequency (RF) antenna coil positioned concentric to the plasma chamber and in proximity to, or in contact with, the outer diameter of the plasma chamber. In some embodiments, the plasma chamber is surrounded by a Faraday shield to prevent capacitive coupling between the RF voltage on the antenna and the plasma within the plasma chamber. High dielectric strength insulating tubing is heat shrunk onto the outer diameter of the conductive tubing or wire used to form the antenna to allow close packing of turns within the antenna coil. The insulating tubing is capable of standing off the RF voltage differences between different portions of the antenna, and between the antenna and the Faraday shield.