Application Exchange

Ion transport and dynamics in GEM micropattern structures

Renato Negrao, CERN

The ion transport and dynamics in micropattern structures is an important aspect to understand and foreseeing possible stability issues with respect to high voltage operation on the microstructure design. The electrons originated from thermo-ionic emissions taking place in regions where the ions are in contact with metallic electrodes - that compose the microstructure and other parts of the detector - could produce further gas ionization, due to the presence of a higher electric fields, leading to a self-sustained gas ionization, and therefore to electrical instabilities inherent to the design.

A detailed investigation of the ion dynamics, for the case of GEM, was performed in order to determine the movement of ions across the microstructure and in the transfer gap. The initial number of ions used on the numerical calculation varies from 1E4 to 1E6 ions. The ions are distributed uniformly in the r-direction and obeying a Gaussian distribution in the z-direction.

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