Re: Tube Type Tesla Coils

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Tube Type Tesla Coils
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 16 Mar 1997 22:48:42 -0600
Approved: tesla-at-stic-dot-net

Subject: 
            Re: Tube Type Tesla Coils
       Date: 
            Mon, 17 Mar 1997 10:12:15 +1200
       From: 
            "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization: 
            Wellington Polytechnic, NZ
         To: 
            tesla-at-pupman-dot-com


Hi all,
         I think it is important when attempting to measure things 
like VSWR and Q (both intimately related BTW) to define the exact 
conditions under which they are to be measured. VSWR (and Q for that 
matter) can be measured at the base of the resonator (it is a 
transmission line, right?). In both cases, the maximum is achieved 
when losses are minimized (and this includes spark losses naturally). 
     But, we want sparks. An infinite VSWR (Q) means nothing when no 
sparks are produced. I submit that our primary (NPI) consideration is:
How do we most efficiently get as much primary energy as possible 
into the discharge (a massive loss)? On a practical level, how do we 
go about minimizing the amount of energy lost in the gap (we can do 
arbitrarily good things as far as wire size, capacitor ESR et. goes)?
This is the one thing I have focused on for the last year or two. For 
a given frequency of operation and a given k (tranfer nee - gap 
conduction time), the higher the surge impedance of the primary, the 
lower the gap losses for a given cap voltage.
     
NB - surge impedance for a given inductance goes down with 
     frequency

   - transfer time increases as k is reduced for a given resonant 
     frequency

   - transfer time for a given k increases as resonant frequency
     decreases

   - gap losses scale approximately linearly with primary current.

   - for a given surge impedance, gap current increases with cap 
     voltage

A few signposts,
Malcolm