Re: Question: Rotary gap designs -water arc

Subject:   Re: Question: Rotary gap designs - loss
  Date:    Wed, 16 Apr 1997 19:46:28 -0400 (EDT)
  From:    richard hull <rhull-at-richmond.infi-dot-net>
    To:    Tesla List <tesla-at-pupman-dot-com>


>btw: related to RHs water-arc experiments : they seem to use similar
>technology in mass drivers. In the publications above there was an
>article "Electrothermal generation of pressure pulses for mass >acceleration" which used water. So, those water-arc explosions are >propably quite a known technology among the rail-gun people. In the >article above they use only 352uF 6kV cap with 17,6kJ of energy.  They >state that they got 38MPa peak pressure pulses. There were references >to IEEE transactions on magnetics, Proceedings of European Symposeum on >electromagnetic launch tech, and somemGerman articles. 
>It seems that there's lots of research being done that is quite
>related to TCs and spark-gaps. It just takes some effort to find
>the publications. Clearly, spark-gaps are not a thing of the past
>but have a clear job with modern high-powered pulsed technology.
>After a day at the library,
>  Kristian Ukkonen.
>| Kristian Ukkonen       |  Do as thou wilt shall be the whole of the
>law |
>| kukkonen-at-alpha.hut.fi  |_____  Chance favours the prepared mind 
>| http://www.hut.fi/~kukkonen |  Fear is the mind-killer  |---------

The Water arc work is quite old.  Dr. Peter Graneau, who ramrods our
research group actually designed magnetic guns (rail guns) for the
defense dept. in the 70s.  The mass water arc acceleration work began
back in the 70s also although electric water arc pressure wave metal
forming goes back much farther.

To accelerate a secondary mass, you need a big cap at lower voltages to
reduce the inertia load on the gun to keep from destroying it with over
pressures.  Thus, the large cap and low volts still provide lots of
joules, but spread out of many milliseconds.  Our special water arc
explosion work involves no acceleration of secondary masses (at least in
the classic ballistic sense), and deals with just the water itself near
the limits of matter's ability to survive huge inertial loads.  Thus, we
use small caps .5-8uf, and very high voltages to get high joule energy
delivered in 10s of microseconds.  Bizarre stuff happens!  the
instantaneous G loading on the small water ejecta jets is on the order
of 30,000 Gs!  We are kissin' the limits of what nature will allow
normal matter to do.

A lot of the gap data in many of these papers, especially gas filled
gaps, is specifically aimed at single pop gaps where many joules are
expected per pulse and the rep rate is very low. 1/sec to 10/day.

Richard Hull, TCBOR