which type of capacitor for pulsed discharge

[LaserTazerPhaser]

I was considering which capacitor is ideally suited for https://www.analog.com/en/products/lt3751.html massively powerful cap charger set to with 3.5amps peak 1.2amps rms at the secondary (shunt set to 9.8mR) it will run for hours and electrolytics might have disfavorable features for this application in which they cease to perform as a capacitor and in an ideal situation they have adequate safetey measures implemented. Its actually far more than 0.74Hz mentioned earlier with the 9.8mR shunt is nearly 1.9607Hz which puts even more of a load onto the capacitor. I just need >300v >32j per discharge cycle.

A constant 1.2A charges 1000uF to 300v in 250ms, with only ~144mW dissipated if the ESR is 0.1R. Even at 2Hz it's less than 100mW average in the cap. so I don't think you need to worry too much about the cap dissipation during charging, just the discharging.

Were is the 0.144w?
Capacitor averaging 24.969W and this is constant charging.

[StillTrying]

Were is the 0.144w?

1.2A * 0.1R

Capacitor averaging 24.969W.

I think you have to take the 0.1R ESR out of the cap and measure the dissipation in the 0.1R separately, it's only 10s of mW using that LT sim.

[Berni]

Were is the 0.144w?
Capacitor averaging 24.969W and this is constant charging.

You are including the power that is getting stored inside the capacitors capacitance. This is where most of the power goes hence why you see a significantly larger figure. To get the power dissipated inside ESR you need to add the ESR externally as a resistor and then measure the power on that, this is the power that goes to heat, the rest is stored.

Also to get the matching results for that equation a current source should be used to charge it.

And yes this internal heating is going to be thousands of times higher in power during discharge, but at least short lasting so it wouldn't cook a capacitor, but might damage any sensitive internal structures where hotspots possibly develop.

[Marco]

Not only the power is higher for short discharges, also the energy ... because for shorter complete discharges the resistive component of the load is by necessity smaller, hence you dissipate more energy in the ESR. With equivalent ESR and load resistance he could be looking at say 50W of average power and that needs a lot of capacitor and surface to dissipate.