A mercury-free high-intensity discharge lamp operating apparatus includes 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 heads of the pair of electrodes; wherein mercury is not included as the luminous material in the arc tube. The present invention satisfies the relationship 0<(100BW/f)-P.sub.0 d<100 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.sub.0 (MPa) is a pressure inside the arc tube during steady-state operation, W(W) is a power consumed during steady-state operation, and f(Hz) is a steady-state frequency during steady-state operation.

Un aparato de funcionamiento de la lámpara de descarga de alta intensidad mercurio-libre incluye una lámpara de descarga de alta intensidad horizontalmente funcionada incluyendo un tubo del arco en el cual un material luminoso sea incluido y un par de electrodos se arregla en el tubo del arco; un lastre incluyendo los medios de una generación de la corriente alterna para proveer la corriente alterna al par de electrodos; y medios de un uso del campo magnético para aplicar en la dirección substancialmente vertical un campo magnético que tiene un componente que es substancialmente perpendicular a una línea recta jefes que conectan del par de electrodos; en donde el mercurio no se incluye como el material luminoso en el tubo del arco. La actual invención satisface la relación 0