Charging Capacitors with DC or AC?

Recently I have bought a pair of Doorknob capacitors.
I have read that these capacitors can be charged with Alternating Current.

While reading a book, I read that is also possible to charge capacitors with Direct Current.

My question is if these Doorknob capacitors can be charged only with AC or with DC also.


33pF 10kV 40kVAR Doorknob Capacitor

A capacitor can be charged with AC but it will be upon reverse polarity discharged, a DC current will charge a capacitor and leave it charged until the voltage is changed. You can charge a capacitor via a diode to not permit it to discharge during the negative portion of the AC cycle, or upon the ceasesing of supply of a DC current. Polarized capacitors can not be charged during the negative portion of the AC cycle, if they are supplied with those voltages the oxide layer and chemistry will fail and the capacitor will become a resistor with a heafty current and likely explode or otherwise fail dramatically.