The Bohm-like expression so derived proved to be very successful
in simulating JET discharges, but failed badly in smaller Tokamaks
such as START.
For this reason a simple gyro-Bohm-like term, also based on dimensional analysis, was added:
This expression is what can be expected from small scale drift-wave turbulence. It is important to note that in large Tokamaks such as JET and TFTR the gyro-Bohm term is negligible, while in smaller machines, with larger values of , the gyro-Bohm term can play a role especially near the plasma centre.