High secondary emission yield (SEY), and the subsequent build-up of a secondary electron cloud, may severely limit the stability of high-intensity particle beams inside particle accelerators. One of the best candidates of beam pipe coating for reduced SEY has been amorphous carbon (a-C) produced by direct current (D.C.) magnetron sputtering. Here we used pulsed laser deposition (PLD), to prepare a-C films from a pure carbon target at substrate temperatures ranging from 300 K to 773 K. The ablating laser was a Nd:YAG system operating at 1064 nm wavelength. With increasing temperature the optical band gap dropped from about 2.1 eV to 1.0 eV. This trend indicates transition from predominantly a-C films to films with more graphitic content, which was also confirmed by Raman measurements. SEY spectra were taken upto 1732 eV of primary electron energy. The maximum SEY value decreased from 1.9 in a-C films down to 1.4 in highly graphitic films deposited at higher temperatures.
|Journal||Physica Status Solidi (C) Current Topics In Solid State Physics|
|Publication status||Published - 1 Jan 2012|