We investigate the situation where an upstream large radius MITL is connected to a downstream small radius MITL of the same vacuum impedance through a magnetically insulated coaxial conical section transmission line of fixed vacuum impedance. When the conical section is long and the load is matched, stable quasi-cycloidal electron motion persists [1]. As the length of the conical section is reduced its vacuum impedance decreases relative to that of the adjacent cylindrical MITLs and the electron sheath flow becomes more complex. When both the load and the conical section MITL are under-matched the electron flow is perturbed to the extent that considerable and persistent vortices appear. For this relatively simple system the complexities of the flow and the onset of vortices are characterized.
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