This is a an L-3 Pulse Sciences (formerly Maxwell Laboratories) 40200 rail gap switch. This switch appears to have been fired very few times as the brass rails show no sign of pitting. Also included is a copy of the user's manual with full descriptions of installation and operation. Model 40200 rail-gap switch is a gas-plasma switch with long, parallel electrodes (the rails for which the switch is named). electrode rails act as multiple spark channels to provide a switching capacity comparable to multiple single-channel switches connected in parallel. Rail-gap switches are used in applications requiring low inductance, fast rise time, and high current and high charge-transfer capability. y are often used in flat-plate transmission line assemblies, configured in either the bipolar or single-polar mode. y can also be adapted to assemblies with coaxial cable transmission lines. • 25 to 50 kV • 30 to 60 kV • 50 to 100 kV • 60 to 120 kV. rail-gap switch operates at a maximum voltage of 120 kV, peak current of 750 kA, and charge transfer capability of 10 C. Switch inductance is 20 nH. Time-delay jitter (one standard deviation) is less than 2 ns. switch consists of three parallel 12-inch electrodes mounted on an epoxy base with a transparent polycarbonate cover. During operation, the switch interior is filled with a pressurized mixture of argon and SF6. Connections for the gas lines are on the top side of the cover. trigger electrode is a knife-edged rail positioned between two brass main electrodes mounted on electrode holders. Slotted holes in the holders allow adjustment of the gap between the main and trigger electrodes. Gap adjustments can modify the operating voltage range of the switch. terminal for the trigger electrode is on top of the switch cover. Brass contact strips on the sides of the switch base serve as terminals for the two main electrodes.