dr mlv+.+ exp d v..av 2R B 2KT For unit volume dnlvx,y7 m(2+n2+2) =no 2kBT expI d v dv.av ckpT Maxwell velocity distribution( ) ( ) x y z x y z x y z v v v k T m v v v k T m N n v v v d d d 2 exp 2 d , , B 3 2 2 2 2 B         + + −          = For unit volume d ( , , ) x y z n v v v Maxwell velocity distribution ( ) x y z x y z v v v k T m v v v k T m n d d d 2 exp 2 B 3 2 2 2 2 B 0         + + −          =