Various types of traveling waves may be injected into a tokamak to continuously sustain the toroidal current. Interest in this problem arises from the possibility of operating tokamak reactors in the steady state. The low‐frequency waves most suitable for this task are identified in terms of the power cost for deployment in a reactor. Means of exciting these waves and tradeoffs with design criteria are discussed. A comparison is made with the alternative attractive regime of high‐frequency waves. Conclusions are based, in part, on the numerical solution of the two‐dimensional Fokker–Planck equation with an added quasi‐linear term due to the waves.