什么是 Hydrodynamic, non-thermal and diffusion-limited escape？

Hydrodynamic escape is the loss of an upper atmosphere that flows away as a whole, heated from above, when its escape parameter is small; the flow may drag heavier particles with it. Non-thermal escape is the loss of particles accelerated by processes other than heat: photochemical reactions that give fragments more than the escape energy, ions picked up by the electric field of the solar wind, sputtering by ions that strike the upper atmosphere, and the outflow of ions along magnetic field lines. Diffusion-limited escape is escape whose rate is set not at the exobase but lower down, by the rate at which the escaping gas can diffuse up through the heavier gas above the homopause, the level above which molecular diffusion, not turbulence, controls the mixture.