Let this represent the total energy of the incident electron.
The effect of divergence of the incident electron beam on the gain of FEL is analysed.
An incident electron can knock an inner-shell electron out of a target atom.
In conditions that the laser gains can be obtained, the relations between the maximal allowable divergence angle of incident electron beam and other physical parameters are discussed.
Relation among energy exponent,incident energy and secondary electron emission coefficient of metal at high incident electron energy
The relations among energy exponent,incident energy and real efficient secondary electron emission coefficient at higher incident electron energy