  Achieving large-scale kinetic modelling is a crucial task for the development
and optimization of modern plasma devices. With the trend of decreasing
pressure in applications such as plasma etching, kinetic simulations are
necessary to self-consistently capture the particle dynamics. The standard,
explicit, electrostatic, momentum-conserving Particle-In-Cell method suffers
from restrictive stability constraints on spatial cell size and temporal time
step, requiring resolution of the electron Debye length and electron plasma
period respectively. This results in a very high computational cost, making the
technique prohibitive for large volume device modeling. We investigate the
Direct Implicit algorithm and the explicit Energy Conserving algorithm as
alternatives to the standard approach, both of which can reduce computational
cost with a minimal (or controllable) impact on results. These algorithms are
implemented into the well-tested EDIPIC-2D and LTP-PIC codes, and their
performance is evaluated via 2D capacitively coupled plasma discharge
simulations. The investigation revels that both approaches enable the
utilization of cell sizes larger than the Debye length, resulting in reduced
runtime, while incurring only minor inaccuracies in plasma parameters. The
Direct Implicit method also allows for time steps larger than the electron
plasma period, however care must be taken to avoid numerical heating or
cooling. It is demonstrated that by appropriately adjusting the ratio of cell
size to time step, it is possible to mitigate this effect to an acceptable
level.
