David-Thomas wrote:

Actually, it wouldn't be impossible at all. You would just connect the IGBT controller to a larger IGBT, add a high speed fan to the head, upgrade the wiring, use a very rugged capacitor bank, and use a  2x voltage multiplier. The voltage multiplier would be very simple, since you would be working with a high input voltage (415 volts).

To regulate the charging current, the simplest thing to do would be to use a rewound transformer from a microwave oven with some of the shunt plates removed to allow 10-15kw maximum power consumption.

The very fact that you've failed to identify any fact which would make it impossible speaks to its possibility.

It would be impossible b because you quote w/s, which is a non existent and impossible unit. Ws is more accurate, but the proper term is Joules anyway. W/s as you put it would mean Watts per second, which no-one with any knowledge of electronics would know. And the "W" should be capitalised.

David-Thomas wrote:
LEDs cannot, and never will rival flash tubes for photography.

Maybe, maybe not. Never is, after all, a very long time. I'm not so sure they really even have to in so far as it really depends on how much light you actually need. While they might not (at least for the time being) be able to match the typical studio head, they do bring many other things to the table - small (a head that you could literally put in your pocket), light-weight, virtually indestructible, very low power requirements, recycle times that no current head can ever hope to meet or even come close to, and the list goes on. An array of 21 high power LEDS can put out an amazing amount of light - roughly equal to 850 W incandescent; the main problem at this point is cost more than anything else.