Dember effect

In physics, the Dember effect is when the electron current from a cathode formula_1 subjected to both illumination and a simultaneous electron bombardment is greater than the sum of the photoelectric current formula_2 and the secondary emission current formula_3.
History.
Discovered by Harry Dember (1882–1943) in 1925, this effect is due to the sum of the excitations of an electron by two means: photonic illumination and electron bombardment (i.e. the sum of the two excitations extracts the electron). In Dember’s initial study, he referred only to metals; however, more complex materials have been analyzed since then.
Photoelectric effect.
The photoelectric effect due to the illumination of the metallic surface extracts electrons (if the energy of the photon is greater than the extraction work) and excites the electrons which the photons don’t have the energy to extract.
In a similar process, the electron bombardment of the metal both extracts and excites electrons inside the metal.
If one considers formula_5 a constant and increases formula_6, it can be observed that formula_7 has a maximum of about 150 times formula_5.
On the other hand, considering formula_6 a constant and increasing the intensity of the illumination formula_6 the formula_7, supplementary current, tends to saturate. This is due to the usage in the photoelectric effect of all the electrons excited (sufficiently) by the primary electrons of formula_5.