Power absorption characteristics of an inductively coupled plasma discharge

Power absorption characteristics of an inductively coupled discharge are investigated experimentally and compared with a two-dimensional inductive heating theory in a planar single turn antenna at high frequency (18 MHz) and low pressure (⩽50 mtorr) conditions. We measure the resistance R, which consists of vacuum resistance R_ν and the plasma resistance R_p for a given RF power of P=½I_c²R, where I_c is the coil current. The vacuum resistance is determined to be 0.44 R in our case. The plasma resistance increases as the gas pressure increases in a pressure range of 2 to 50 mtorr. Also, it increases with power. In a high-pressure range near 50 mtorr, however, it has a nearly constant value of about 0.6 Ω