Mapping of the Transient Electric Field Created by the Charge Spreading on the Resistive Strip of Micromegas used in the ATLAS New Small Wheels
Resistive strips Micromegas are employed in the ATLAS New Small Wheel project. They have been already installed and operate in the experimental cavern of the ATLAS experiment at CERN. This work attempts to describe the mechanism of the surface electric charge spread on a resistive strip of the Micromegas detector and the created transient electric field. Moreover, an approach utilising the Telegraph partial differential equation, used in transmission lines, is discussed assuming a 2-layer geometry approximation. Finally, the transient electric field formation leading to the strong suppression of the sparks in the amplification region is calculated by using the accurate 3-layer geometry for the particular parameters of the Micromegas configuration. The spatial mapping of this field versus time is presented for the time slice of interest.