Well, they can be charged with AC, as that is how a tesla coil works. The key is positioning the spark gap distance such that it will break down when the maximum voltage of the AC cycle is achieved across the caps.
[Being Facetious] If your capacitors can store an AC voltage, then you better file for a patent [/Being Facetious].
Crafter_Man, Trigonal_Planar hasn’t described the circuit of the Tesla coil properly.
It’s a resonant circuit, with the Tesla coil’s primary in series with the capacitor. The capacitor charges within a single half-cycle of the 60 Hz driving voltage. Once the breakdown voltage of the spark-gap is reached, a much higher frequency oscillation begins.
See schematic here.
Thanks Desmostylus. Trigonal seemed to be implying that a capacitor can “store an AC voltage,” which is obviously not true. But as you noted, a capacitor can store instantaneous energy at instantaneous voltages in a sine wave…
You could have problems, Trigonal_Planar.
Some caps are rated for a.c. voltages, some for d.c.
If you’ve got a 22 kV a.c. rating, you’re probably O.K.
If you’ve got a 22 kV d.c. rating, you’re pushing it. The 15 kV rms rated transformer has a peak voltage of 15 kV x √2 = 21 kV. The transformer output voltage could well have a tolerance of ±20%, meaning an actual peak voltage of up to 25 kV.
On preview:
No worries, Crafter_Man.