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Initial planning for interferometry measurements on triggered plasma opening switch source

Digest of Technical Papers-IEEE International Pulsed Power Conference

Lynn, A.G.; Jackson, Daniel P.; Gilmore, M.A.; Savage, Mark E.; Sharpe, R.A.

The Triggered Plasma Opening Switch (TPOS) at SNL is a unique device that exploits the high conductivity and low mass properties of plasma. The TPOS's objective is to take the initial ∼0.8MA (∼250ns rise time) storage inductor current and deliver ∼0.5MA at ∼2.4MV (∼10ns rise time) to a load of ∼5-10Ω. Configuration advantages include low current jitter and resistive voltage drop, power gain, and minimization of trigger input power as the result of using two stages in series. This two-stage design is novel and is the first to demonstrate operation of magnetically triggered stages. Study of TPOS characteristics is in progress via an offline interferometer diagnostic; specifically, a laser interferometer will be used to make density measurements of the source plasma. It is thought that the gross plasma source density is ∼1014 cm-3, but details of the spatial structure and temporal evolution have not previously been studied. In order to better understand switch operation, these details are essential. Presently two interferometer systems are planned for testing: a temporary 1 μm system for initial plasma characterization, and a 10.6 mu;m laser system for routine use. We will start with a single chord measurement then upgrade to a multi-chord system. Future plans involve varying plasma source parameters, such as magnetic field strength and plasma fill time, in order to understand the density dependence on these parameters. Improved knowledge of the plasma source density behavior should allow for improved switch operation. © 2005 IEEE.

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Initial design and results from an ion current collection diagnostic for the triggered plasma opening switch experiment

Jackson, Daniel P.; Savage, Mark E.; Seidel, David B.

Study of the triggered plasma opening switch (TPOS) characteristics is in progress via an ion current collection diagnostic (ICCD), in addition to offline apparatus. This initial ion current collection diagnostic has been designed, fabricated, and tested on the TPOS in order to explore the opening profile of the main switch. The initial ion current collection device utilizes five collectors which are positioned perpendicularly to the main switch stage in order to collect radially traveling ions. It has been shown through analytical prowess that this specific geometry can be treated as a planar case of the Child-Langmuir law with only a 6% deviation from the cylindrical case. Additionally, magnetostatic simulations with self consistent space charge emitting surfaces of the main switch using the Trak code are under way. It is hoped that the simulations will provide evidence in support of both the analytical derivations and experimental data. Finally, an improved design of the ICCD (containing 12 collectors in the axial direction) is presently being implemented.

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6 Results
6 Results