The L55/12.M Crew Served Coilgun from Kaelo Engineering is the newest advancement in electromagnetic weaponry. Using advanced switching technology and high quality superconductors this long range, 12-stage anti-armour device can be carried by a team of 4 and rapidly assembled in a position of your choosing. Capable of firing a 2kg tungsten projectile in a ferromagnetic sabot at up to 4.7 km/s. These small and very high velocity projectiles will bypass shields and all but the most advanced point defense systems to neutralize almost any ground based target or even low flying aircraft in a pinch! Just dont forget to anchor the tripod and properly calibrate the recoil dampening system! Kaelo Engineering, bringing a secure future to you at hypersonic velocity.
Kaelo Engineering is not responsible for injuries resulting from spontaneous destructive quench events or field containment failure. No ferromagnetic objects, other than Kaelo approved ammunition, should be located within 5 meters of the L55/12.M during operation, discharge all coils promptly after use. Read L55/12.M operators manual FOM2187 in full prior to use, included with each gun and tripod package. Ammunition supplied seperately.
So that's the general idea, one issue. I'm trying to figure out a compact method of powering a 22MJ system like this. Compact fusion reactors exist in this universe but even the smallest models are still too heavy for a 4 man team to carry in the field. What are some probable near near-future (within 50 years or so) power generation/storage systems that can make this a practical system in both energy output and weight?
As mentioned before: Needs to be relatively light weight, enough for a single man to practically carry. 60 pounds absolute maximum or easily disassembled into pieces and reassembled.
Use known or theoretically feasible technology given proper advancement.
Not be unreasonably dangerous to operate or carry over rough terrain.
Edit: Optional: Quiet enough to maintain a level of stealth given proper concealment and preparation time.