A glow discharge lamp includes a light-transmitting envelope containing a rare gas fill material. The envelope contains a spherical-shaped region having a predetermined internal radius R. A phosphor coating is disposed on the inner surface of the envelope. Anode and cathode electrodes are disposed within the envelope and spaced a predetermined distance d thereapart. The voltage drop of the cathode electrode is less than the excitation potential of the rare gas fill material. The anode electrode has a predetermined effective surface area S.sub.a such that the relationship Rd/S.sub.a is within the range of from about 5.0 to 11.0.