Both in Ohmically and beam-heated $L$-mode discharges of ASDEX, the electron-temperature ($T_e$) profile shape can be varied over a wide range by the choice of the safety factor $q_a$. The power-deposition profile, on the contrary, has no effect on the $T_e$ profile shape. In current-free W-VII-A stellarator plasmas, no such invariance property is found. An independent constraint seems to fix the current distribution $j\left(r\right)\mathrm{}$ of the tokamak, which defines the conditions of electron heat transport.

• Received 4 February 1986

DOI:https://doi.org/10.1103/PhysRevLett.56.2187