impedance 10 is resistive at any significant current power levels losses in a resistive element would be substantial and would yield low efficiency due to high i 2 r it is more practical to use a reactive element where it is common to be net inductive to limit turn on losses by controlling the di dt through action of the series inductance in the power driver fig3 shows several potential load lines 11 12 13 and the possible intercept points on the gas plasma load lines at two different plasma temperatures t 1 and t 2 at different control conditions it is well known in the art that with frequency as the control variable and a substantially inductive series element the slope of the load line can be moved around the voltage axis intercept 16 as seen in fig3 line 11 at a lower frequency line 12 higher than line 11 and line 13 higher than line 11 and 12 also it is known that by adjusting the voltage intercept point 16 determined by the voltage source 33 of fig2 the load line position can be altered but unlike the frequency control parameter the slope remains constant fig4 shows the direction of change off the load lines 17 18 and 19 the direction of change is in the direction of a line perpendicular 20 to the slope of any one of the lines at a constant frequency or in other words if the frequency is constant and the dc rail voltage is increased from v 17 to v 18 and then to v 19 the.