  One of the main features of two-phase detectors with electroluminescence (EL)
gap being developed in our laboratory for dark matter search is the extensive
use of THGEMs (Thick Gas Electron Multipliers). In various versions of the
detector, the THGEMs are used as electrodes in the gas and liquid phases to
form the drift, electron emission and EL regions, as well as for avalanche
amplification of a signal in the gas phase. In this work the simulations of the
electric field and electron transport through such THGEM electrodes were
performed. In the liquid phase, these simulations allowed to determine the
optimal parameters, such as the hole diameter of THGEM and applied voltage
across it, that can provide effective transmission of the electrons from the
drift region to that of the EL gap. In the gas phase, the effect of the THGHEM
voltage on the electric field uniformity in the EL gap was studied.
