Similarity rules in plasma physics

A complete set of criteria determining the similarity of physical phenomena in a plasma is derived; the discussion concerns both the similarity of collisionless plasma and collisional plasma. By application of these criteria to fusion confinement of hot plasma it is shown that for similar experiments the plasma density n varies as B ex 2 , the containment time tau varies as 1/B ex , where B ex is an external magnetic field; thus the determining factor for controlled fusion, the product n. tau is growing proportionally with the intensity of external magnetic field.