The variation of the secondary electron yield and of the desorption yield of copper under electron bombardment: Origin and impact on the conditioning of the LHC

The operation of most radio-frequency components in accelerators rely on the conditioning obtained usually by gradually increasing the power fed into these devices. This effect is related to the reduction of the desorption yields and of the secondary electron yields of surfaces exposed to electron bombardment. In LHC, similar decreases will also limit the detrimental consequences of the electron cloud phenomenon on the beam stability, the power deposited in the cryogenic system and the gas density. The parallel evolution of the desorption yield and of the secondary electron yield will be discussed and compared to the changes to the surface composition as observed by surface analytical techniques. The possible origin of the secondary electron yield decrease will also be discussed at the light of these new results.