Debye-Huckel theory for spheres of diameter a with charges +/-q is ext
ended to general dimension d. Explicit results include Bjerrum associa
tion of +/- ions and the dipole-ionic solvation energy. For all d > 2
a critical point terminates conducting-liquid-conducting-vapor coexist
ence: The critical density rho(c) = rho(c)a(d) falls with d SE arrow
2, but T-c = k(B)T(c)a(d-2)/q(2) rises. When d = 2, an insulating vap
or appears for T less than or equal to 1/4 (the Kosterlitz-Thouless p
oint), separated from conducting fluid by an infinite-order critical l
ine ending at a tricritical point: rho(t) = rho(c)*(d --> 2) similar
or equal to 0.004, T-t = T-c*(d --> 2) less than or similar to 1/4 fo
r rho > rho(t)* the transition is first order.