Strobing very high power LEDs
Nah, don't bother charging and discharging a cap like that.  Just PWM it after the cap.  The LEDs will be fine.  Get a power supply of the right voltage, add a nice big cap at the output to reduce ripple in the power supply, then use a decent MOSFET transistor driven by some sort of PWM controller.  Either high side or low side will work, but one may be a little more straightforward to implement.  Generally low-side is easier to implement when you have to control something that runs at a higher voltage than the control logic.  An Arduino could generate a PWM signal, or you could build something out of discrete logic or analog components (e.g. ramp generator and comparator).  Doesn't really make too much difference.