The parameters of plasmas, including their spatial and temporal extent, vary by many orders of magnitude.
It allows the results of laboratory experiments to be applied to larger natural or artificial plasmas of interest.
The situation is similar to testing aircraft or studying natural turbulent flow in wind tunnels with smaller-scale models.
The choice of nondimensional parameters is never unique, and it is usually only possible to achieve by choosing to ignore certain aspects of the system.
One commonly used similarity transformation was derived for gas discharges by James Dillon Cobine (1941),[1] Alfred Hans von Engel and Max Steenbeck (1934).