The Halo Thruster is a new type of electrostatic plasma thruster having the innovative feature of a magnetic null region near its anode. In order to assess the influence of this magnetic cancellation region on the physics of operation, a new 2D cylindrical electrostatic Particle-In-Cell (PIC) model was developed from the ground up in which electrons, ions and neutral particles were represented as super-particles. The plasma inside the Halo Thruster acceleration channel was investigated at 100V, 150V and 200V anode voltages. At 100V anode voltage, thrust T , specific impulse Isp, electric potential ϕ, ion density ni, and electron temperature Te were measured experimentally using a thrust stand and a Langmuir probe by a previous Ph.D. student. The simulation was able to capture some features of the discharge measured experimentally including the ϕ distribution, ion collision with outer dielectric wall, distribution of ni and increase of Te with anode voltage. However, some departures between the simulations and experiments were noted. Most significantly an under estimate of the electron temperature Te .