It depends on what you re shooting at it and how high you can tune the plasma frequency. It s a tough requirement to meet at present. Cloaking mirrors A nearer-term application is cloaking. With the proper adjustments, a plasma can be made into a kind of energy mirror, reflecting back or away incoming electromagnetic waves, such as those emitted from ground-based radars. In essence, any spacecraft outfitted with this kind of plasma field would be completely cloaked from the probing attentions of radar operators.
Nothing reflects back.
But don t expect completely impervious shields anytime soon. Any number of technical issues remains to be solved, not the least of which is exactly how to make cold plasmas dense enough to withstand attack. But In a strict sense, I don t consider that plasma shielding. Less immediately space-like, but no less practical, are biological applications. Cold plasmas allow for rapid decontamination of clothing, equipment or personal gear.