Optical and electrical investigations of a high power Lorentz Drift based gas discharge switch

Summary form only given. For switching high current and high voltage there are two completely different physical principles. One method is based on the use of semiconductors but limited in voltage, where as the other is based on a triggered breakdown in gases or in vacuum. Now this contribution gives an introduction in a new kind of a triggered gas discharge switch. This new switch consists of a coaxial electrode geometry. At the initial state the inner electrode acts as high voltage anode whereas the outer coaxial electrode as cathode. Similar to the plasma accelerator the self induced magnetic field will force the discharge to the open end of the coaxial electrode system. The nomenclature is based by its underlying effect to Lorentz drift switch (LDS). The main advantages of the system are the low inductive set up of the coaxial electrode configuration and the loval erosion rate during operation. The Lorentz drift discharge is a low pressure gas discharge which is positioned on the left branch of a breakdown voltage curve, similarly to the Paschen curve. One important feature of a high voltage and high current switch is the reliability for triggering. A surface flashover trigger was mounted outside the coaxial electrode system. With this external trigger system a gas breakdown is initiated and forms a conductive plasma sheath and penetrates through bore holes into the main gap and closes the switch. For first investigations voltage- and current measurements were preformed. For a voltage lower than 2.5 kV current chopping was observed. For time resolved investigation of the cathode spots and propagation of the moving arc a fast shutter camera will be used. Further, the speed of the moving arc was detected by a fast photodiode and was determined to a maximum speed of almost 60 km/s.