Abstract
The high energy emission of microquasars is thought to originate from highenergy particles. Depending on the spectral state, the distribution of theseparticles can be thermal with a high temperature (typically 100 keV) ornon-thermal and extending to even higher energy. The properties of high energyplasmas are governed by a rich microphysics involving particle-particlecollisions and particles-photons interactions. We present a new code developed to address the evolution of relativisticplasmas. This one-zone code focuses on the microphysics and solves the coupledkinetic equations for particles and photons, including Compton scattering,synchrotron emission and absorption, pair production and annihilation,bremsstrahlung emission and absorption, Coulomb interactions, and prescriptionsfor additional particle acceleration and heating. It can in particular describemechanisms such a thermalisation by synchrotron self-absorption and Coulombcollisions. Using the code, we investigate whether various acceleration processes, namelythermal heating, non-thermal acceleration and stochastic acceleration, canreproduce the different spectral states of microquasars. Premilinary resultsare presented.