  We demonstrate that spin current can be generated by an ac voltage in a
one-channel quantum wire with strong repulsive electron interactions in the
presence of a non-magnetic impurity and uniform static magnetic field. In a
certain range of voltages, the spin current can exhibit a power dependence on
the ac voltage bias with a negative exponent. The spin current expressed in
units of $\hbar/2$ per second can become much larger than the charge current in
units of the electron charge per second. The spin current generation requires
neither spin-polarized particle injection nor time-dependent magnetic fields.
