Suppression of secondary emission in a magnetic field using triangular and rectangular surfaces

The effect of surface roughness on the secondary electron emission from a sawtooth and isosceles triangular surface as well as a rectangular surface in a magnetic field under electron bombardment is investigated using a Monte-Carlo method. In all cases, some of the secondary electrons emitted from the surface return to the surface within their first few gyrations, resulting in a low effective secondary electron yield. Either sawtooth or isosceles triangle surface can significantly reduce the secondary emission yield in a magnetic field below the multipacting threshold with a weak dependence on the size of the surface and magnetic field. Rectangular surfaces can also reduce SEY below 1.0 but have a large sensitivity to the size of the grooves and the magnetic field. The impedance as well as other implementations of the grooved surfaces are also discussed.