NOVELTY - The apparatus has an insulating comb tooth (M) that is locally contained at multiple places in a rotation direction between the windings of the air-core solenoid coils (AL-1,BL-1). The toroidal coils (AL-2,BL-2) are provided for containing a toroidal core (106) connected in series with the solenoid coils so as to block noise of lowest high frequency. A cylindrical conductor is provided for forming a distributed constant line to accommodate or surround solenoid coil so as to combine with solenoid coil, and form parallel resonance on a frequency.    USE - Apparatus for processing plasma to substrate such as semiconductor wafer and glass substrate using plasma-etching apparatus such as capacitive coupling type plasma-etching apparatus. Can also be used for processing plasma to flat panel display, organic electro-luminescence (EL), substrate for solar cell, photomask, clear plastic (CD) substrate, and printed circuit board using microwave plasma-etching apparatus, inductive coupling plasma-etching apparatus, helicon wave plasma-etching apparatus, plasma chemical vapor deposition(CVD) apparatus, plasma oxidation apparatus, plasma nitriding and sputtering apparatus.    ADVANTAGE - The cylindrical conductor is provided for forming a distributed constant line to accommodate or surround solenoid coil so as to combine with solenoid coil, and form parallel resonance on a frequency. Thus, the efficient and stable reliable high impedance is given with respect to the high frequency noise of harmful frequency entering on the track such as feed line and signal wire from the high frequency electrode and other electrical portion in a processing container. Hence, the reproducibility and reliability of plasma process are improved effectively while improving the wafer temperature control function of heater system which in turn prevents the leakage of power of the high frequencies from the chamber on a heater feed line through the heat generating case of susceptor.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the filter unit.    Resin-made top connector (90)    Toroidal core (106)    Air-core solenoid coils (AL-1,BL-1)    Toroidal coils (AL-2,BL-2)    Insulating comb tooth (M)