The effect of gas ion bombardment on the secondary electron yield of TiN, TiCN and TiZrV coatings for suppressing collective electron effects in storage rings

In many accelerator storage rings running positively charged beams, multipactoring due to secondary electron emission (SEE) in the beam pipe will give rise to an electron cloud which can cause beam blow-up or loss of the circulating beam. A preventative measure that suppresses electron cloud formation is to ensure that the vacuum wall has a low secondary emission yield (SEY). The SEY of thin films of TiN, sputter deposited non-evaporable getters and a novel TiCN alloy were measured under a variety of conditions, including the effect of re-contamination from residual gas.