Abstract: An electrodeless discharge tube containing an ionizable fill, the tube having a first portion for insertion in a launcher and a further portion separated from the first portion by a partition wall. Hence a discharge can be excited in the further portion because a surface wave can propagate through the wall separating the first and further portions.

Abstract: A discharge tube arrangement comprises an excitation device and a discharge tube made of a light-transmissive dielectric material and containing a fill. The excitation device is suitable, when energized with radio frequency (r.f.) power, for exciting surface waves in the discharge tube. The excitation device includes a launcher and a plurality of electrical components associated with the supply of r.f. power to the launcher and constituting at least one of an impedance matching network and a part at least of means to generate r.f. power. This plurality of electrical components is positioned in the launcher between its inner and outer tubes.

Abstract: A discharge tube arrangement for use as a light source includes a discharge tube made of a light-transmissive dielectric material and containing a fill. An excitation device for exciting surface waves in the discharge tube comprises an r.f. power generator and a launcher. The launcher is formed as an inner tube, an outer tube coaxial with the inner tube and first and second end walls, at least one of the first and second end walls having an aperture for receiving the discharge tube. A launcher gap extends axially from a first end of the inner tube and there is also a further gap. The outer tube and the first and second end walls form an unbroken electrically conductive path to provide an r.f. screening structure around the inner tube.

Abstract: A discharge tube arrangement includes a discharge tube of a light-transmissive dielectric material and containing a fill. An excitation device for exciting surface waves in the discharge tube comprises an r.f. power generator and a launcher. The launcher is formed as an inner tube, an outer tube coaxial with the inner tube, and first and second end walls, at least one of the first and second end walls having an aperture for receiving the discharge tube. Means are provided inside the launcher for coupling r.f. power to the inner tube. A body of dielectric material extends from the inner tube to the outer tube, thereby to hold the tubes in fixed relative positions, the body encasing the coupling means.