Help me make a matching box at 70 MHz for a VHF power supply

I am interested in making a matching box at the frequency of 70MHz for a VHF power supply. The application is plasma enhanced CVD or a sputtering chamber. The chamber size is 1 * 3 feet. The power supply can deliver a maximum of 1.5KWatts. I want some help regarding the simulator to estimate the value of the capacitor that are required. I have tried to build a matching box for the above requirement without much success also resulting in arching. I am attaching snap of my matching box. I am using an L type configuration with two vacuum capacitors. Any suggestions would be of great help.