The influence of the Bθ on MPOS performance

The plasma opening switches (POS) are interesting because of the possibility to create high power pulse generators with the inductive energy store. The POS with microsecond conduction time (MPOS) are of particular interest allowing to eliminate the water forming lines in generator design. The GIT-4 experience had shown that the further progress in this field would be determined by solving of two major problems. The first is the increase of the conduction time, tc. At a given output voltage the increase of tc results in an increase of the power delivering to the inductive storage. The second is the problem with the MPOS resistance at opening. Its value determines the output voltage and power of the generator pulse. To solve this problems the proper physical understanding of the MPOS operation is necessary. Up to now the complete picture is not clear. The NRL model successfully reproduces short conduction POS results but fails by MPOS analysis. More recently two other papers were published with a common idea that the POS operation in two regimes (short and long conduction) is different. In the last work the difference in hydrodynamical plasma displacement under the influence of jxB forces was discussed-when the switch current rises slowly the plasma displacement exceeds many times that of the rapidly rising current. Assuming that the opening occurs when plasma center-of-mass (CM) moves the distance ∼0.5l, where l is the length of the initial plasma fill, the authors successfully explained some important MPOS features. This work was performed to prove some conclusions of this idea