SUMMARYHigh‐temperature inert gas (argon) plasma magnetohydrodynamic (MHD) electrical power generation using a linear shaped channel with Hall and diagonal connections has been conducted. It is revealed by observation by using a high‐speed camera that the MHD power‐generating plasma is almost entirely stable regardless of the connection type. Enthalpy extraction ratios of 5.6% for the Hall connection, 6.7% for the diagonal connection (diagonal angle 53° to 66°), and 10.1% for the diagonal connection (diagonal angle 36° to 48°) have been achieved under the operating conditions of an inlet total temperature of 9000 K, an inlet total pressure of 0.105 MPa, and a magnetic flux density of 4.0 T. The output power can suffer from a low electric field in the upstream region in a Hall connection, and is improved under the no Hall current condition in a diagonal connection.