We have developed a simple analytical model for the electric and ponderomotive (trapping) potentials in linear ion traps. We have used this model to calculate the required voltage drive to our mercury trap, and the result compares well with our experiments. The model gives a detailed picture of the geometric shape of the trapping potential and allows an accurate calculation of the well depth. The simplicity of the model allowed us to investigate related, more exotic trap designs which may have advantages in light‐collection efficiency.