ALF: why not DRSSTC?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Hello all,

This message is particularly aimed at Greg Leyh, but I would like 
comments from others as well.

As far as i know (and i might be wrong) Greg is currently working on 
a scale model of his ALF towers.  This prototype uses the OLTC 
topology to drive the Tesla resonator.  Since silicon appears to be 
the weapon of choice already, I'm curious as to why not DRSSTC 
instead of OLTC?  It seems (at least on our hobbyist level) that the 
DRSSTC can outperform an OLTC for similar amount of silicon 
used.  The DRSSTC also does not have the difficulties that the OLTC 
intruduces as far as primary coils are concerned (many OLTCs are just 
1 or 2 turn primaries).  The DRSSTC also does not have to store the 
entire bang energy in the tank cap (another benefit)

One possible issue i could see is this:  1200V devices will only get 
you so far until you are looking at using single turn primaries and 
giant tank capacitors (resembling the OLTC, but this is even more 
problem for OLTCs as they scale up as well).  So you might be forced 
to look at 1700V or 3300V devices.  But I'm aware that these devices 
also have their limitations (they are slower and have greater losses, 
but i think these are not much to overcome).  Ive heard that the real 
problem is from cosmic rays causing the devices to turn on or 
avalanche (what is the exact mechanism?) when you don't want them 
to.  But, wouldn't this also be a problem with using higher voltage 
silicon in the OLTC?

So for each problem I see with scaling a DRSSTC to ALF size, it seems 
an OLTC would have the same problems.  As I (and others) see it, the 
DRSSTC is overall a better topology.  So to summarize: why OLTC over 
DRSSTC?  I'm guessing Greg has thought about this more than i have, 
so i would really like to hear his response.

Thanks,

Steve Ward