On Feb 11, 7:21*pm, K7ITM wrote:
On Feb 11, 5:38*pm, Jim Lux wrote:


In other high power RF applications, low Z can be desirable (because
you'd rather take the IR hit than deal with the high voltage).

In the pulsed nuclear research business you see lines with Z of a few
ohms in pulse forming networks ften using distilled water as the
dielectric.. that epsilon of 80 gets the C right up there so Sqrt(L/C)
is small.

Yes, indeed a low impedance can be helpful sometimes...but the times
I've been involved with low-Z lines, they've almost always been
unbalanced (e.g. coaxial). *For a PFN, the high epsilon is also an
advantage in storing a lot of energy. *Since even very pure water is
pretty conductive (relative to seriously good dielectrics), I'm a bit
surprised it's used.

Both coaxial and parallel plate balanced.. For short pulses, the water
isn't all that conductive (because it takes time for the water
molecules to dissociate); you worry more about particulate or gas
bubble contaminants cause a dielectric breakdown.

For a spectacular example, look at the Z-machine.