Cap Dissipation Factor, Plasic Capacitors for TC tank

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Sean Taylor by way of Terry Fritz <twftesla-at-qwest-dot-net>" <taylorss-at-rose-hulman.edu>

What exactly is the cap dissipation factor - i.e. is it just a
representative figure used to tell how much a cap will dissipate? How does
frwquency figure into it, and how do you measure the dissipation of a cap?
I ask because a) I am curious, and b) I have a Plastic Capacitors 0.05 uF,
20 KVDC cap and want to know it's suitability for TC tank use.  I doubt that
it is any good for a TC tank because the thing is so tiny, well, about 2" x
3" x 4" without insulators.  Maybe a mylar dielectric?  Any thoughts greatly
appreciated!
Sean Taylor