Richardson-Dushman equation

From the Richardson-Dushman equation, the current density Je by thermionic emission can be obtained as... 

Thermionic emission. The number of electrons which escape from the metal surface increases rapidly with temperature (thermionic emission). In general, the higher the temperature and the lower the work function, the higher is the electron emissivity. The current density can be calculated by the Richardson-Dushman equation (in the absence of an external electrical field), according to i — AT exp(—rp/kT), where A is the Richardson constant (A cm K ), T is the temperature (K), and

work function (eV). For pure tungsten A — 60.2 (A cm K ) [1.91]. The thermionic current (A cm ) can then be calculated as i — 60.2r exp(—52230/T) [1.37]. 

When a metal sample is heated, electrons are emitted from the surface when the thermal energy of the electrons, kT, becomes sufficient to overcome the work function O [53]. The probability of this electron emission depends on work function O and temperature T as expressed in the Richardson-Dushman equation ... 

In thermionic emission, the current density / obtained from the electrically heated filament in the presence of an electric field E obeys the modified Richardson-Dushman equation ... 

The thermionic-emission current /th> in amperes, generated by a heated filament is described by the Richardson-Dushman equation... 

Electron emission current density (A/m ) can be calculated by the following Richardson-Dushman equation (Chodorow and Susskind, 1964) ... 

Richardson-Dushman equation An equation of electron saturation emission current density from a heated cathode. It states that the emission electron current density is proportional to the square of the cathode temperature and an exponential of negative constant times a reciprocal of the absolute temperature of the cathode. The proportionality constant is 6.02 x 10" and the negative constant depends on the cathode material. 

Richardson equation (Rlchardson-Dushman equation) SeexHERMioNic emission. 

According to the Dushman-Richardson equation, the electron current upon heating a substrate of work function O is given by... 

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