Hi alone6288,

your plasma will be very far from any equilibrium, so rules for equilibria like Le Chatelier and Kc don't apply.

At identical pressure and temperature, 1L of N_{2} and H_{2} mixture can't make 0.7L of NH_{3}, because the product has twice as many atoms per mole.

My intuition, and nothing more, tells that a plasma favours small molecules, so extracting the NH_{3} as soon as it's produced seems necessary.