A New Algorithm for Simulating Space-Charge Limited Flow

In particle-in-cell simulation, generating a space-charge limited electron source presents challenges due to the steep gradients in electron density and electric field infinitesimally close to such an emitting surface. Simulating accurate emission current densities is essential for modeling complex microwave device geometries such as that of the magnetron. These simulations are complicated by the device geometry, which is resolved using cut-cells on a Cartesian grid. We will discuss modeling strategies for space-charge limited emission on planar cut-cell boundaries, and present convergence studies to evaluate their accuracy in both simple and complex geometries. As applications, we show simulation of explosive emission in a magnetron and magnetically insulated line oscillator (MILO). For the MILO, we show that this new emission algorithm results in the appearance of harmonics of the main frequency in the absorbed current.