Mercury-free high-intensity discharge lamp operating apparatus and mercury-free metal halide lamp

A mercury-free high-intensity discharge lamp operating apparatus comprising:

• a horizontally operated high-intensity discharge lamp including an arc tube in which a luminous material is enclosed and a pair of electrodes are arranged in the arc tube;
• a ballast including an alternating current generation means for supplying alternating current to the pair of electrodes;
• and
• a magnetic field application means for applying in substantially vertical direction a magnetic field having a component that is substantially perpendicular to a straight line connecting the heads of said pair of electrodes;
• wherein mercury is not included as the luminous material in the arc tube, and at least a rare gas is included in the arc tube;
• and
• satisfying the relationship
• 0<(10BW/f)−Pd<10
• wherein B(mT) is the magnetic field applied to a center between the heads of the pair of electrodes, d(mm) is a distance between the heads of the pair of electrodes, P(MPa) is a pressure of the enclosed rare gas at 20° C., W(W) is a power consumed during steady-state operation, and f(Hz) is a steady-state frequency during steady-state operation.

A mercury-free metal halide lamp, comprising

• an arc tube in which a luminous material is enclosed and a pair of electrode are arranged in the arc tube;
• wherein at least an indium halide serving as the luminous material and a rare gas are contained in the arc tube;
• and
• mercury is not included as the luminous material in the arc tube;
• satisfying Pd≦4.6, wherein d(mm) is a distance between the heads of the pair of electrodes, and P(MPa) is a pressure of the enclosed rare gas at room temperature;
• and
• further comprising a magnetic field application means for applying a magnetic field having a component that is substantially perpendicular to a straight line connecting the heads of the pair of electrodes, thereby suppressing arc curving.