Before revision: The emission current density (J) from the cathode, as a function of its thermodynamic temperature T, in the absence of space-charge, is given by Richardson's law: where = elementary positive charge (i.e., magnitude of electron charge), = electron mass, = Boltzmann 's constant = , = Planck 's constant = , = work function of the cathode, = mean electron reflection coefficient.
After revision: The emission current density (J) from the cathode, as a function of its thermodynamic temperature T, in the absence of space-charge, is given by Richardson law: where = elementary positive charge (i.e., magnitude of electron charge), = electron mass, = Boltzmann constant = , = Planck 's constant = , = work function of the cathode, = mean electron reflection coefficient.