High Voltage, high current switching

[asymmetric_implosion]

A review article in IEEE Transactions on Plasma Science by Anders Larsson (Gas-Discharge Closing Switches and Their Time Jitter) provides a nice overview of high current, high voltage switches that are relevant to the plasma focus. (DOI 10.1109/TPS.2012.2185815). It is behind a pay-wall but for those with access it covers many of the technical issues of gas switches for pulse power devices. For the person looking for a bit more, it is a nice read with plenty of references.

[delt0r]

There is a lot more in that issue that just this paper, solid state LVA, other switch articles etc. looks like some may even be good! I got about 20-30 that i want to scan and i expect at least 5 or so will be detailed reading. Big llink to the above article below. You can’t download without a subscription. Can’t wait for open access everywhere (My institute has a subscription).

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6152158&contentType=Journals+&+Magazines&sortType;=asc_p_Sequence&filter=AND(p_IS_Number:6324463)

[asymmetric_implosion]

The regular issue companion to this special issue on pulse power also has some new results from Kansas State’s PF device.

[andrewmdodson]

If you could configure a gas discharge switch to turn off precisely, interrupt the current in many large inductors. Force them into a parallel configuration and obtain very high currents and multiples of your charging current. The series inductors can charge up a large current with a fairly low voltage over a few seconds. This is known as the XRAM current multiplier (the inductive inverse of the MARX voltage multiplier)

A big advantage is inductive energy storage is 10x denser, meaning a much lower cost and smaller total size. I have a gut feeling that the inductive coil might very advantageous to the beam extraction concept. A current choke averages out the energy pulses of the collection coil and the firing system. I cannot say conclusively if this will give a faster current rise time than a capacitive discharge.

Development of a combined opening switch for the project of generator on inductive storages
Abstract

[em]The article proposes a fundamentally new approach to the problem of breaking high currents of 100kA or more. The vacuum discharger and the vacuum interrupter differ significantly in the rate of electric strength recovery, size of electrode erosion and etc. This is due to the difference in the type of the discharge. In the report considered we suggested that to align these values the current I should be closed through the spark gap prior to moving the electrodes of the vacuum interrupter; at this its value is above the initial by ΔI (ΔI-current, ΔI/I0 ~5÷10·10-2). The excess ΔI-current flows through the vacuum interrupter, but in the reverse direction. In the course of moving the electrodes apart, the ΔI-current falls to zero with a time constant t=L/R, where L and R are the inductance of the contour (vacuum interrupter- spark gap) and resistance of the discharge of the discharge gap, respectively. This makes it possible to quickly recover the electric strength of the gap between the contacts, substantially reduce the electrode erosion and significantly decrease the breaking voltage of the ΔI-current. At the final stage the discharge of the countercurrent battery recovers the vacuum strength of the discharge gap. Such method of current breaking allows for the effective interruption of direct currents of high power. The method was developed in terms of the combination current breaker (vacuum interrupter and plasma opening switch). Spark gap is replaced to mobile plasma gap in design of combination opening switch. The article considers -construction of switch; -described of action steps; -energy characteristics of circuit, in the context to progress of conception pulsed generators based on inductive storage.[/em]

[Author]

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