>>485967>plasmaUntil we figure out plasma instability, we can't make sophisticated plasma configurations like a stable plasma ball.
However a plasma projector that acts like a highly localized shield against most types of weapons is conceivable. Think about a long range sandblaster wearing down incoming weapons fire with ionized particles. But we probably don't have a power-source for that, I'm guessing 200 gigawatts continuous is the barrier to entry for this.
>anti-matter bulletsWe can't use anti-matter as the main energy carrier, because we can't make that stuff in quantity, and because we can't do low enough tolerances to make storage reliable enough.
We probably don't want to set off anti-matter explosions anyway since it will cause really nasty highly energetic particle emissions that make the stuff that comes out of nukes look harmless by comparison.
It is more plausible to use a few anti-matter particles as a means to set off a really small fusion reaction, (maybe with an intermediate fission reaction to further economize on anti-matter, which at the moment is the most expensive stuff by a huge margin). You can trap a few anti-matter particles in a magnetic vacuum bottle, if you have good enough or cold enough superconductor material.
There is a somewhat more low-tech way to make "nuclear bullets" small enough even for a regular rifle. It requires synthesizing a specific radio-active fissionable element, so it's not a cheap proposition by any means. And those bullets also would require a lot of cooling so there would be practicality limits of carrying a big ammo refrigeration unit around. If you set it off it would generate mostly gamma radiation but it would be powerful enough to melt a tank into a puddle of molten metal.
I'm not sure where you are going with this, but if i had to guess i'd say you are trying to make weapons munitions really small ? Maybe you can explain your motivation for that ?