Structure and propagation speeds have been determined for thermonuclear deflagration waves (fusion flames) in idealized, magnetically confined, deuterium - tritium plasmas. A one-dimensional time-dependent numerical code using multi-fluid and magnetohydrodynamic equations and detailed treatments of alpha particle energy deposition and radiative energy transfer was used. In all cases studied, deflagration waves with well defined structures form and propagate through the plasma with a speed of , where is the ion density , B is the magnetic field (T), and u is the local plasma fluid velocity.