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A kinetic treatment is developed for collisionless magnetized plasmasoccurring in high-temperature, low-density astrophysical accretion disks, suchas are thought to be present in some radiatively-inefficient accretion flowsonto black holes. Quasi-stationary configurations are investigated, within theframework of a Vlasov-Maxwell description. The plasma is taken to beaxisymmetric and subject to the action of slowly time-varying gravitational andelectromagnetic fields. The magnetic field is assumed to be characterized by afamily of locally nested but open magnetic surfaces. The slow collisionlessdynamics of these plasmas is investigated, yielding a reduced gyrokineticVlasov equation for the kinetic distribution function. For doing this, anasymptotic quasi-stationary solution is first determined, represented by ageneralized bi-Maxwellian distribution expressed in terms of the relevantadiabatic invariants. The existence of the solution is shown to depend onhaving suitable kinetic constraints and conditions leading to particle trappingphenomena. With this solution one can treat temperature anisotropy, toroidaland poloidal flow velocities and finite Larmor-radius effects. An asymptoticexpansion for the distribution function permits analytic evaluation of all ofthe relevant fluid fields. Basic theoretical features of the solution and theirastrophysical implications are discussed. As an application, the possibility ofdescribing the dynamics of slowly time-varying accretion flows and theself-generation of magnetic field by means of a \textquotedblleft kineticdynamo effect\textquotedblright\ is discussed. Both effects are shown to berelated to intrinsically-kinetic physical mechanisms.

Kinetic description of quasi-stationary axisymmetric collisionless accretion disk plasmas with arbitrary magnetic field configurations