Workstation CPU coolers have a larger base, for example : NH-U12S TR4-SP3
I couldn’t find drawings, but from the pictures it looks to be around 7.5cm, which should be enough to cover the LES.
use water, have a pump and radiator!!
[cpu coolers sometimes use water]
or thermoelectric cooler [forget how they do that]
maybe maybe not
you want highest surge/peak/max current, not highest energy capacity
those 2 are mutually exclusive
usually ‘vaping’ cells have that - the highest peak, and they are also $$$$
What about LiFePO4 battery? You know, those brick looking batteries, like 50Ah?
Thank you for the suggestion. I will be ordering parts in a week or two, so I will try to find the best solution
idk , you have to decide what current to run the LED at, then get a battery that can do that
you possibly need to limit the current and control it, which would be hard at say 20A
if you just connect the LED directly to the battery-that-can-deliver 75A, there might be smoke and fire, as my EE prof dr feaster used to say
i think [someone correct me] that lithium ion have the highest peak current
not lithium-iron-phosphate, which are safer from explosions, but have less energy and current max
i may be confused about that
The difference it slight but it really does depend on the alloy, for both. Usually these comparisons are given for base metals but the alloying additives can change qualities a little or a lot. Like 7075 aluminum does not dissipate nearly as well, and the secret 8xxx proprietary alloys even less (or, for example, the super hard gritty aluminum alloys that are often used in car parts). You can find the heat shedding figures on good metal supplier sites and the various “engineering tool box” sites. It’s not a huge deal though, and in a flashlight we’re totally overwhelming this property anyway.
I thought it was lithium polymer but i haven’t looked at it in years so things might’ve changed…?
Heat pipes was going to be my next suggestion though the build will be more complex.
Looks like that vapour chamber i linked is close but no cigar
Either way it sounds like you’ve done a lot of research so far and probably have something in mind. I’m keen to see you build it 
Another idea is a large peltier plate
Good LED for a 90cm searchlight mirror.
6 x 41v = 246v
48a÷6=8a
Inverter with a bridge rectifier on the output. Maybe an scr could be used for dimming. If it was me I would try it but I can understand if some think it is a dumb thing to do.
A Peltier plate will add more heat to be dissipated. A rough estimate is twice the heat. It needs substantial current as well, easily around 2kW power alone for cooling this LED.
Does the LED manufacturer suggest a cooling device?
Maybe build your own heatpipe or vapor chamber for this.
Or use a copper baseplate as a heat spreader and four of these huge Xeon coolers to shovel away the heat of the 2kW LED, without Peltier.
have you thought about beam shape, mirrors, lenses, TIR?
That was my thought, however the beefiest Xeon I was able to quickly find in terms of TPD is ~330W. Suspect that getting >4 of those to interface with a primary cooling loop might be more involved than simply using something larger.
Well, there is always the cooling solution of a cerebras chip.
(just kidding) 
Yes, still undersized, but regarding available power sources, these will shut down before heat can build up enough. Adding a 2kW++ gas engine alternator would surely exceed the definition of “flashlight” and “portable”, but the engine could as well serve to drive a cooling compressor, allowing continous operation at full power.
Yes I’ve done some research, and all solutions are just too small, like 7cm. But as you said, I have something in mind and a trick up my sleeve. You’ll see 
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It’s hard to find something that big, but it will be an OP reflector with glass lens. The problem is how to attach the lens to reflector…
I will order some parts soon, so before that I can change my solutions. Can you explain what you mean, or link parts I can use?