In the ALPHA experiment cold (~10 Kelvin) charged plasmas of positrons are trapped in Penning-Malmberg traps. Bunches of antiprotons are inserted into these plasmas in order to create antihydrogen atoms through three-body recombination. These antihydrogen atoms are then used for high-precision studies of fundamental matter-antimatter symmetries. In this project we will try to simulate the behaviour of the plasma during mixing with the antiprotons in order to better understand the process. This is a process that has been considerably refined over a number of year, but though it works, a better understanding would help to improve the number of antihydrogen atoms trapped in the experiment. This in turn would help to improve precision of current experiments, as well as maybe make entirely types of experimental studies possible in the future. The main questions we want to address are: - Are the strongly magnetized positron plasmas in the ALPHA experiment in thermal equilibrium? - Can we better understand the so-called rotating wall process that is experimentally used to compress the radius of the plasma? - Dynamics when positrons and antiprotons are mixed and how they depend on antiproton number etc.? - The amount of adiabatic cooling of the positrons. - The rate of thermalization of antiprotons in the positron plasma. - Heating and expansion processes.