The dependence of the absorbed RF-power on the diameter of the plasma column was examined experimentally in the density region of 1011 cm−3 to 2 × 1012 cm−3, using a QP-machine. Setting the absorbed RF-power P proportional to dγ (d is the diameter of the plasma column), the calculation for a uniform plasma column yields γ = 4. However, the experimental value of γ is less than 2. It is shown that the effect of an inhomogeneous density profile makes γ less than 2 and the density profile is important in the efficient heating of a plasma.