Re: [EVGRAY] Re: multipacting and secondary emission electron multiplication

Body

Ole,

Thanks for the good info.

Do you know if a high speed avalanche transistor creates an FM
modulation as does a spark gap?

On 12/28/2018 2:16 PM, [email protected] [EVGRAY] wrote:
>  
>
> Hi Mick,
>
> "Can you explain how and if avalanche currents in certain transistors can
> mimic multipaction and the electron multiplication of secondary emission?"
> The second breakdown
> <https://wiki2.org/en/Second_breakdown#Secondary_breakdown> acts like
> an avalanche that can't be stopped except by disrupting the current
> from outside the transistor. The first breakdown is kind of like the
> Zener effect while the secondary breakdown is a negative resistance
> characteristic where the transistor shorts.
>
> "You mentioned awhile back a concept of power multiplication through
> avalanche mode rather than resonance as the system could be much less
> finicky.  Could you elaborate on this concept?"
> The avalanche is like a solid state spark gap and happens very fast
> like in a few nsec or less.
> https://wiki2.org/en/Avalanche_transistor
>
> Bipolar transistors optimized to be used in avalanche mode:
> https://www.diodes.com/products/discrete/bipolar-transistors/special-function-transistors/avalanche-transistors/
> Normal bipolar transistors aren't optimized for avalanche mode
> operation and their breakdown parameters may vary a lot even having
> the same type number. They'll still show the breakdown effect.
>
> Understanding Power Transistors Breakdown Parameters:
> https://www.onsemi.com/pub/Collateral/AN1628-D.PDF
>
> "It is interesting to note that during multipaction events much of the
> technology present is designed to limit the amplification event to
> prevent damage to the devices."
> If the device melts or explodes it's no longer useful. This is a good
> reason for limiting the effect. This means the current must be limited
> or cut off from the outside as the device can't do it after being
> triggered.
>
> Regards
> Ole
>
>
>
> --In [email protected], <mkjekyll@...> wrote :
>
> Ole,
>
> Can you explain how and if avalanche currents in certain transistors can
> mimic multipaction and the electron multiplication of secondary emission?
>
> You mentioned awhile back a concept of power multiplication through
> avalanche mode rather than resonance as the system could be much less
> finicky.  Could you elaborate on this concept?
>
> It is interesting to note that during multipaction events much of the
> technology present is designed to limit the amplification event to
> prevent damage to the devices.
>
> Great data here:
>
> https://en.wikipedia.org/wiki/Multipactor_effect
>
> More intense version:
>
> https://arxiv.org/ftp/arxiv/papers/1112/1112.2176.pdf
>