A YAG head producing greater than 1J per pulse isn't a very small system.. in fact it's pretty freaking huge. What exactly are you looking to do with it?
SSY won't make near 1J.. maybe 100mJ if you're lucky. 1J is a damn big pulse.. I don't own an SSY, but I don't think you can set the pulse duration to be long enough to make 1J of total output energy.
There are two limits, the amount of energy the flash lamp can handle, and the saturation of the nd:yag crystal. If the PFN delivers long pulses in the flash lamp, the lamp will hold (that is it won't explode).
There are no problems whatsoever to get a PFN to discharge in 3-4ms. You put in the 100-150J of electrical, about 1J will come out.
It's not really a big problem, unless you specify the pulse length, 1J in 10ns and 1J in 4ms are worlds apart.
Sounds like you've got firsthand experience.. I was merely sourcing Sam's Laser FAQ for my info. Quote regarding the SSY-1 from one of the best and most experienced hobbyists around:
Beam characteristics.
Wavelength: 1,064 nm.
Divergence: A few mR (not yet measured).
Quality: A simple positive lens will focus the beam to a microscopic spot.
Output energy: Estimated between 10 and 50 mJ. It is at least equal to "1 Alcoa". The laser will punch a hole in kitchen-strength aluminum foil when focused (but doesn't do razor blades using the 15 J PFN). Over 100 mJ is possible on "lively" units up at 900 V on the PFN1. However, repeated operation at these energy levels tend to destroy the Q-switch and adjacent rod AR coating.
Lasing medium.
Type: Nd:YAG rod, AR coated ends.
Rod diameter: about 4 mm.
Rod length: about 50 mm.
Lasing threshold: less than 7.5 J (100 us pulse duration).
Flashlamp - This looks similar to an ordinary photographic variety, perhaps somewhat higher quality, but not the very high quality EG&G FXQ style lamp. It may be a FXQG-264-1.4 or FXQSL-559-1.4. See the section: Shawn's High Energy Experiments with the SSY1 Laser Head.
Arc length: 35 mm (about 1.4 inches).
Outside diameter: 5 mm.
Inside diameter: 3 mm.
Overall length: 75 mm.
Ko impedance parameter: 16 ohms-amp0.5 (estimated).
Flashlamp envelope: quartz.
Electrodes: machined solid tungsten.
Minimum voltage: less than 300 V.
Maximum voltage: greater than 1,000 V.
Maximum energy input at 100 us pulse duration: 25 J (guessed!).
Recommended energy input at 100 us pulse duration: 15 J at 900 V.
If we're hitting the rod with 150J, it seems like we're a ways outside the recommended incident pump energy to me, thereby risking a drastically shortened lifetime..
nd:yag damage threshold....700 mega watts/cm2
150joules in 3 miliseconds....50 kilo watts? nope, you won't do anything to the rod.
Anyway, even a red LOC diode will put out 1J, if it's running at 200mW in a 5 seconds interval it will put out exactly 1 joule. 1 Watt = 1 Joule/1 Second.
My point wasn't that you should buy a ssy1, my point was that joules mean nothing unless you also tell the time or the application.
To get 3-4ms pulses, you will need to remove the Q-Switch as he said above. Coatings on the rod are likely fine, the peak power when Q-Switched is higher. Mirrors are fine, they take a lot of energy.
I missed the "remove the q-switch" part.. in fact I'm still not seeing it. Interesting learning experience for me here in this thread, though.. makes me want an SSY.