High-intensity vapor arc-lamp

Claim 2

A lamp as in claim 1 wherein the reactive metal substance is located within an evacuated chamber separated from said alumina envelope by a partition which is oxygen-permeable at operating temperature.

Claim 3

A lamp as in claim 1 wherein the reactive metal substance is yttrium, yttrium hydride, a compound of yttrium heat decomposable to yttrium, or an alloy of yttrium.

Claim 4

A lamp as in claim 1 wherein the reactive metal substance is cerium, a cerium base alloy, or a heat-decomposable compound of cerium.

Claim 5

A lamp as in claim 1 wherein the reactive metal substance is lutetium, a lutetium alloy, or a heat-decomposable compound of lutetium.

Claim 6

A high intensity vapor arc lamp comprising an inner arc tube of alumina ceramic having electrodes sealed therein and containing a sodium-mercury reservoir and an inert starting gas, the partial pressure of sodium in said arc tube being in the range of 30 to 1,000 torr in operation, and an evacuated outer vitreous jacket surrounding said arc tube, in combination with a reactive metal substance within said lamp arranged to be in oxygen communication with the inner surface of said arc tube, said metal of said substance having over a given temperature range a free energy of reaction in the formation of its oxide more negative than the free energy of formation of sodium aluminate within said arc tube, said substance being so located within said lamp as to achieve during operation a temperature within said range in order to prevent cleanup of sodium by formation of sodium aluminate within said arc tube.

Claim 7

A lamp as in claim 7 wherein the reactive metal substance is located within said alumina arc tube.

Claim 8

A lamp as in claim 7 wherein the arc tube is provided with oxygen-permeable end closures and the reactive metal substance is located in the interenvelope space between inner arc tube and outer vitreous jacket.

Claim 9

A lamp as in claim 7 wherein the reactive metal substance is yttrium, yttrium hydride, a compound of yttrium heat decomposable to yttrium, or an alloy of yttrium.

Claim 10

A lamp as in claim 7 wherein the allumina arc tube is sealed with niobium end caps and the reactive metal substance is attached to an end cap.

Claim 11

A lamp as in claim 11 wherein the reactive metal substance is yttrium.

Claim 12

A lamp as in claim 7 wherein the allumina arc tube is sealed with niobium end caps, one of which is provided with a dummy niobium exhaust tube containing a charge of yttrium.

Claim 13

A lamp as in claim 13 wherein said dummy exhaust tube is not hermetically sealed relative to the interenvelope space.

Claim 14

A lamp as in claim 7 having niobium end caps sealed to the alumina arc tube by a sealing composition comprising aluminum oxide, calcium oxide and magnesium oxide, and wherein the reactive metal substance is yttrium.

Claim 15

A lamp as in claim 7 wherein niobium end caps are sealed to the alumina arc tube by a sealing composition comprising aluminum oxide, calcium oxide and magnesium oxide, and wherein one of the niobium end caps is provided with a dummy niobium exhaust tube containing a charge of yttrium.

Claim 16

A lamp as in claim 16 wherein said dummy exhaust tube is not hermetically sealed relative to the interenvelope space.

Claim 17

A high intensity vapor arc lamp comprising: a. an inner arc tube of alumina ceramic having electrodes sealed therein and containing: a1. a quantity of mercury sufficient to establish a partial pressure therein during lamp operation to support a high current electric arc; a2. a quantity of sodium halide sufficient to partially vaporize during lamp operating temperature and establish therein a partial pressure of approximately 10-3 to 200 torr sodium halide vapor in equilibrium with an excess of liquid sodium halide; and a3. a partial pressure of an inert starting gas; b. an evacuable outer vitreous envelope; and c. a reactive metal substance within said lamp arranged to be in oxygen communication with the interior of said arc tube, c1. said metal of said substance having over a given temperature range a free energy of reaction in the formation of its oxide more negative than the free energy of formation of sodium aluminate within said arc tube; and c2. said substance being so located with in said lamp as to achieve during operation a temperature within said temperature range in order to prevent cleanup of sodium by formation of sodium aluminate within said arc tube.

Claim 18

A lamp as in claim 18 wherein the reactive metal substance is located within said alumina arc tube.

Claim 19

A lamp as in claim 18 wherein the arc tube is provided with oxygen-permeable end closures and the reactive metal substance is located in the interenvelope space between inner arc tube and outer vitreous jacket.

Claim 20

A lamp as in claim 18 wherein the reactive metal substance is yttrium, yttrium hydride, a compound of yttrium heat decomposable to yttrium, or an alloy of yttrium.

Claim 21

A lamp as in claim 18 wherein the alumina arc tube is sealed with niobium end caps and the reactive metal substance is attached to an end cap.

Claim 22

A lamp as in claim 18 wherein the reactive metal substance is yttrium.

Claim 23

A lamp as in claim 18 wherein the alumina arc tube is sealed with niobium end caps, one of which is provided with a dummy niobium exhaust tube containing a charge of yttrium.

Claim 24

A high intensity vapor arc-lamp comprising: an inner arc tube of alumina ceramic having electrodes sealed therein and containing: a1. a quantity of sodium sufficient at operating temperatures to establish therein a partial pressure of sodium of approximately 10-3 to 460 torr of sodium vapor in equilibrium with excess liquid sodium; and a2. respective quantities of at least two other metals selected from the group consisting of thallium, cadmium, and mercury in quantities sufficient to provide respective partial pressures of each metal present in equilibrium with excess liquid metal and sufficient to combine with sodium partial pressure to sustain a light-emitting electric arc which as a white spectral appearance and high intensity; and b. a reactive metal substance in oxygen communication with the interior of said alumina envelope; b1. said metal of said sUbstance having over a given temperature range a free energy of reaction in the formation of its oxide per mole of oxygen more negative than the free energy of formation of sodium aluminate per mole of oxygen within said alumina envelope; and b2. said substance being so located within said lamp in order to prevent cleanup of sodium by formation of sodium aluminate within said alumina envelope.

Claim 25

A lamp as in claim 25 wherein the reactive metal substance is located within said alumina arc tube.

Claim 26

A lamp as in claim 25 wherein the arc tube is provided with oxygen-permeable end closures and the reactive metal substance is located in the interenvelope space between inner arc tube and outer vitreous jacket.

Claim 27

A lamp as in claim 25 wherein the reactive metal substance is yttrium, yttrium hydride, a compound of yttrium heat decomposable to yttrium, or an alloy of yttrium.

Claim 28

A lamp as in claim 25 wherein the alumina arc tube is sealed with niobium end caps and the reactive metal substance is attached to an end cap.

Claim 29

A lamp as in claim 25 wherein the reactive metal substance is yttrium.

Claim 30

A lamp as in claim 25 wherein the alumina arc tube is sealed with niobium end caps, one of which is provided with a dummy niobium exhaust tube containing a charge of yttrium.