to: Marco

You might wish to try a convential RSG to begin with.  At 6000 RPM you will
be way over-quenched and achieve very poor performance from a classic coil
system --- unless you are running a magnifier design, then it will work


> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Date: Monday, January 04, 1999 7:12 AM
> Original Poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi> 
> I am designing a TC with a 62 kHz oscillating frequency. As I would like
> quench at the first notch with a rotary gap, I supposed I can set my
> coupling coeff. so that the first notch will come after about 5
> oscillations at 62 kHz. That makes about 80 us to reach the first notch.
> So the quest is how to achieve such a short quenching time.
> >From available literature I found that a spark can possibly form when
> electric field exeeds 40 kV/cm and surely forms when it exeeds 70 kV/cm.
> So, if you write down how the stationary and rotating electrode distance
> evolves with time, and calculate the time the electric field is greater
> than 40 kV/cm, you should get a rough figure of your quench time.
> I did that and for a peak voltage of 60 kV, rotating speed of 6000 rpm,
> rotor diameter of 12" I got a quench time of over 500 us (!). Because I
> cannot reasonably increase either speed or rotor diameter, I took the
> book's solution and designed to insert a static spark gap in series with
> the rotary one.
> By doing that I plan to decrease the voltage at the RSG down to 15 kV:
> way the theoretical quench time drops down to 100 us, that gives at least
> some hope to achieve the required 80 us.
> I was thinking to use a high resistance voltage divider to have 15 kV on
> the RSG and 45 kV on the static gap. The static gap would be a series of
> sections, to easily set its trigger voltage. The voltage divider should
> also remove a part of the randomness involved in air gap trigger voltage.
> Any suggestions or comments about the above story?
> Thanks to everybody.