An improved apparatus for material processing, wherein the improved apparatus including a plasma processing system to process a substrate, the plasma processing system including a process chamber, a substrate holder, and a plasma source. The plasma source further includes an inductive coil assembly for inductively coupling RF power to plasma wherein the inductive coil assembly is arranged within a process chamber. The inductive coil assembly includes an inner conductor, a slotted outer conductor, and a dielectric layer. The inductive coil assembly can further include a second dielectric layer in order to protect the slotted outer conductor from plasma. The inner conductor is surrounded by the slotted outer conductor and, between which, resides the first dielectric layer. The second dielectric layer encapsulates the inner conductor, first dielectric layer and the slotted outer conductor.