MX2008007582A - Ceramic arc chamber having shaped ends - Google Patents

Abstract

Arc chambers (10) for discharge lamps, such as ceramic metal halide lamps, have ends (28), where the electrodes for the arc chambers are introduced, that are configured such that, when the arc chambers are arranged vertically, the metal halide additives in the arc chambers will accumulate substantially only on the inner surfaces (34) of the ends, which can have closure walls (30) that are thicker than the thickness of the walls of the body portions (12) of the arc chambers. The ends can be further configured such that the metal halides are deposited substantially uniformly in a thin layer over the ends of the arc chambers. The ends can also be configured in a manner that no sharp edges are provided at the ends of the arc chambers so that corrosive effects to the arc chamber resulting from localized temperature variations are minimized.

Description

CHAMBER OF ARCH OF CERAMIC WITH EXTREMOS WITH FORM Field of the Invention The present invention relates generally to arc chambers 5 for discharge lamps, such as ceramic metal halide lamps and in particular, the invention relates to the construction, shape and configuration of the ends of the ceramic arc chambers, wherein the electrodes for the chambers are introduced into the chambers. BACKGROUND OF THE INVENTION Discharge lamps, such as metal halide lamps, produce light by the ionization of a filler material, such as a mixture of metal halide and mercury additives, which evaporates when the lamp is turned on. The ionization is carried out in a transparent or translucent discharge chamber that is formed of a ceramic material, such as polyaluminium alumina. The discharge chamber, often referred to as an arc tube or arc chamber, contains electrodes that are adapted to be connected to a 0 electr circuit. ico When the electrical circuit is energized, an electric arc is established between the electrodes and the filler material after it evaporates and ionizes and the light is generated. The ceramic arc tube or chamber may have a variety of shapes such as cylindrical, spherical or oblong, for example in the case of an arc tube having a cylindrical shape, the arc tube may comprise a continuous external wall which may be a little elongated. The opposite ends of the arc tube may be closed with ceramic end pieces. In that case, a respective ceramic leg is It engages with each end piece and the respective electrode is inserted through the opening in the leg and a complementary opening in the end piece, so that the tip of the electrode is placed within the space surrounded by the continuous external wall of the tube. As a result, the tips of the electrodes will be confronted with each other and will be placed properly to establish an arc with each other when the electrodes are energized. When in use, the arc chamber can be configured so that the electrodes adopt a vertical orientation, with one end of the arc chamber and one accompanying electrode and the end piece located below the other end of the chamber and an electro and the end piece The lower end of the arc chamber in such orientation typically comprises the coldest region of the arc chamber, to be the region where the metal halide additives tend to be collected. Halide additives Metals that are used in the filling material often comprise rare earth halides. This is the case where metal halide additives and in particular, rare earth halide additives, are corrosive to ceramic materials, such as The polymeric alumina 11 na and the corrosion caused by the additives can result in premature failure of the ceramic arc tube.

This circumstance is exacerbated when the temperature gradients that are created in the end piece at the bottom of the arc tube are such that they cause the metal halide additives to be collected at the bottom of the end piece and against the outer wall of the end piece. arc tube, when the outer wall of the arc tube joins the lower end piece The alumina from the inner surface of the outer wall is dissolved by the additives, which causes the arc tube to fail When increasing the thickness of the arc tube the external wall is not a satisfactory solution, since by doing so, the lumen output of the lamp is decreased. Other difficulties associated with the arc tube chambers, whether they are oriented vertically and horizontally, involve bowing the arc chambers and the cracking of arc chambers It would be convenient to have ceramic arc chambers that avoid these problems Brief Description of the Invention In accordance with one aspect, the invention relates to a ceramic arc chamber for a discharge lamp comprising a body portion having a continuous external wall, which includes an outer surface and an inner surface and surrounding a space adapted to contain electrodes and metal halide additives The continuous external wall includes a first end and a second end that are longitudinally spaced from one another and define the longitudinal boundary of the continuous outer wall At least the first The end of the continuous outer wall has an opening within the space that is surrounded by the continuous external wall. An end piece is located in the opening at the first end of the continuous external wall and is joined to the inner surface of the continuous external wall. The end piece has a closing wall which is generally arranged axially of the longitudinal boundary of the continuous external wall and an outer surface and an inner surface facing the space surrounded by the continuous external wall. The inner surface of the The continuous external wall of the body portion and the inner surface of the closure wall of the end piece are configured to thereby fuse in such a way that their melting line and the inner surface of the closure wall do not provide sharp edges in the interior. the ends of the ceramic arc chamber adjacent to the first end of the continuous external wall In accordance with another aspect, l The invention relates to a ceramic arc chamber for a discharge lamp, which comprises a body portion and at least one end piece configured in particular. The body portion has a continuous external wall that includes an outer surface and a inner surface and surrounding a space adapted to contain electrodes and metal halide additives The continuous external wall includes a first end and a second end that are longitudinally spaced from one another and defining the longitudinal limit of the outer wall Continuous The body portion adapts to be fixed, during use so that the longitudinal limit of the outer wall continues is positioned so that the first end of the continuous external wall is located below the second end of the continuous external wall At least the first end of the continuous external wall has an opening within the space that is surrounded by the continuous external wall An end piece is located in the opening in the first end of the continuous external wall and joins with the inner surface of the continuous external wall. The end part has a closing wall which is arranged, usually in axial form of the longitudinal limit of the continuous external wall and has a thickness greater than the thickness of the continuous external wall The end piece has an outer surface and an inner surface that confronts the space surrounded by the continuous external wall The inner surface of the wall continuous external portion of the body portion and the inner surface of the closure wall of the end piece, are configured in such a way that The metal halide additives will essentially accumulate only on the inner surface of the closure wall and the harmful accumulation of the metal halide additives against the inner surface of the outer wall of the body portion is prevented. of the ceramic arc chamber According to a particular aspect, the configuration of the inner surface of the closing wall is such that a thermal profile is established between the first end and the second end of the arc tube which causes the Metal halide additives are deposited essentially uniformly on the inner surface of the end wall of the end piece According to another aspect, the inner surface of the closure wall of the end piece includes an inclined portion and a portion that is arranged inwardly of the inclined portion, relative to the space that is surrounded by the continuous external wall and below of the inclined portion when the ceramic arc chamber is arranged for use The inclined portion essentially joins the inner surface of the continuous outer wall with the portion of the inner surface of the closing wall, is arranged inwardly of the inclined portion and below the inclined portion In accordance with another aspect, the inner surface of the closing wall of the end piece has a curvilinear profile The curvilinear profile of the inner surface of the closure wall extends inwardly from the inner surface of the continuous external wall, relative to the space surrounded by the outer wall of the body portion and down when the ceramic arc chamber is arranged for use In accordance with another aspect, the inner surface of the closure wall of the end piece has a spherical configuration extending towards in from the interior surface of the continuous external wall, relative to the space surrounded by the continuous outer wall and downwardly when the ceramic arc chamber is arranged for use In a particular embodiment, the outer surface of the wall of the ceramic closure the end piece has an essentially conical configuration Also, in another aspect of the invention, the outer surface and the surface Inside of the continuous external wall are essentially cylindrical In another aspect, the first end of the continuous outer wall includes a terminal portion that forms a support for the end piece. The end piece includes a flange portion extending axially outwardly from the longitudinal limit of the outer wall. it continues and rests on the terminal portion of the continuous outer wall. In another aspect, the end piece comprises an injection molded end part. In another aspect, each of the first end and the second end of the continuous outer wall have an opening. within the space that is surrounded by the continuous external wall and the respect similar end pieces are located in the openings so that the first end or the second end of the continuous external wall can be located under the other when the arc chamber Ceramic is arranged for use BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an elevated, exploded, cross-sectional view of a first embodiment of the invention. Figure 2 is an exploded, elevated, cross-sectional view of a second embodiment of the invention. Figure 3 is an elevated, exploded, cross-sectional view of a third embodiment of the invention Detailed Description of the Invention Figures 1, 2 and 3 illustrate three respectembodiments of the invention With reference first to Figure 1, an arc chamber, indicated generally with the number 10, for a discharge lamp, such as a ceramic halide lamp and made of a material such as the polypstamma alumina comprises a body portion, indicated generally with the number 12 The body portion 12 has a continuous external wall 14 which includes an outer surface 16 and a surface 18 inside and surrounding a space, indicated generally, with the number 20 As described in more detail below, the space 20 is adapted to contain electrodes and metal halide addit, not shown. The continuous outer wall 14 includes a first end 22 and a second end 24 which are longitudinally spaced from one another and define the longitudinal limit of the continuous external wall When in use, the camera 10 of The arc is placed in the manner illustrated in Figure 1. Accordingly, the body portion 12 is adapted to be arranged when in use, so that the longitudinal boundary of the continuous outer wall 14 is positioned in such a way that the first end 22 of the continuous external wall is located below the second end 24 of the continuous external wall At least, the first end 22 of the continuous external wall 14 has an opening 26 within the space 20, which is surrounded by the continuous external wall In the embodiment of the invention, shown in the Figure 1 the second end 24 of the continuous outer wall 14 has an opening that is similar to the opening 26, but the opening in the second end 24 is illustrated as closed by the end piece, which will be described later in detail Now with Referring to the first end 22 of the continuous external wall 14 and the opening 26 located therein, it can be seen that the opening 26 is adapted to recean end piece, indicated generally, with the reference number 28, which is an exploded view of Figure 1, shown as removed from the opening 26. When assembled, the end piece 28 is located in the opening 26 at the first end 22 of the continuous external wall 14 and joins the surface 18 interior of the continuous external wall Typically, the end piece 28 is made of the same ceramic material as the body portion 12 and the end piece 28 joins the interior surface 18 of the continuous external wall 14 to the fusion the two components together, such as with a cleaning process. The end piece and the continuous outer wall can also be joined with other processes, as is known to those skilled in the art. The end piece 28 has a wall 30 of generally arranged closure, axially of the longitudinal limit of the continuous outer wall 14 The closing wall has a greater thickness than the thickness of the continuous external wall 14, as can be seen in Figure 1 The wall 30 of closure has an outer surface 32 and an inner surface 34 that faces the space 20 that is surrounded by the continuous external wall 14 The first end 22 of the continuous outer wall 14 includes a terminal portion 36 that forms a support for the end piece 28 and the end piece includes a flange portion 38 extending axially outwardly from the longitudinal limit of the wall continuous external 14 and rests on the terminal portion 36 of the continuous external wall In the embodiment of Figure 1, the structures of the second end 24 of the continuous external wall 14 and the end piece 28 attached to the second end 24 are similar to the described for the first end 22 of the continuous external wall and the end piece 28 adapted to be joined to the first end 22 In one aspect, the end pieces may comprise injection molding parts although the end pieces may be formed in another way, such as by pressing or machining, for example The end pieces 28 also include ceramic legs 40 which are fixed to the closure wall 30. As shown in Figure 1, it is These legs are essentially narrower than the width of the closure wall 30 and as will be understood by those skilled in the art, they support the electrodes, not shown, which are used with the arc chamber 10. In general, it can be observed that the tips of the electrodes are located within the space 20 and extend through the closure wall 30 and into the opening 42 in the legs 40, where they are held and sealed in place by a ceramic layer, a glass seal or a cermet (composed of ceramic and metal), for example As noted above, each of the first end 22 and the second end 24 of the continuous outer wall 14 has an opening within the space 14 that is surrounded by the continuous outer wall In the embodiment illustrated in Figure 1, the respective, similar end pieces 28 are located in the openings so that the first end 22 or the second end 24 of the outer wall continues 14 can be located below the other when the ceramic arc tube 10 is arranged for use. Typically, the ceramic arc tube when in use, will be arranged so that the end pieces 28 are aligned vertically, as shown in FIG. shown in Figure 1 The ends of the electrodes opposite the tips of the electrodes extend beyond the ends of the legs 40 and are connected to an electrical circuit that can be connected to a source of electrical energy for the purpose of energizing The electrodes As indicated above, when the electrodes are energized, an electric arc is established between the tips of the electrodes. The electric arc evaporates and ionizes the filler material in the arc chamber, including the metal halides, such as the rare earth halides that are part of the filler material and thus, the light is generated. The filler material, which includes the metal halides, will be condensed and will fall to the first end 22 of the arc chamber 10 As mentioned above, metal halides are corrosive and can cause the arc tube to fail This is the case when metal halides are allowed to accumulate in a form which come into contact with the inner surface 18 of the outer wall 14, which is typically relatively thin According to this, the invention allows to diminish the opportunity for the metal halides to be accumulate in such a way as to cause the arc tube to fail. In general, to achieve this result, the inner surface 18 of the outer continuous wall 14 of the body portion 12 and the inner surface 24 of the part closure wall 30 28 are configured in such a way that they are fused in such a way that the metal halide additives will essentially accumulate only on the inner surface 34 of the closure wall 30 and will be distributed over a large area in a thin layer and prevented the significant harmful accumulation of metal halide additives against the interior surface 18 of the continuous external wall 14 of the body portion 12 of the ceramic arc chamber 10 The above result is achieved in the embodiment of Figure 1, as follows The interior surface 34 of the closure wall 30 includes an inclined portion 44 and a portion 46 which is arranged inwardly of the inclined portion 44, relative to a space 20 that is surrounded by the continuous external wall 14 and below of the inclined portion when the ceramic arc chamber 10 is arranged to be used as illustrated in Figure 1 The inclined portion 44 essentially joins the interior surface 18 of the continuous external wall 14 with the portion of the interior surface 46 of the wall 30 of closure which is arranged inwardly of the inclined portion 44 and below the inclined portion. As a result, the metal halides that settle on the first end 22 of the ceramic arc tube will not accumulate in such a way as to adhere much to the inner surface 18 of the outer wall Rather, they will tend to collide with the inclined surface 44 and will remain there or flow downward to the portion of the surface 46 interior The closing wall that is thicker that the thickness of the external wall 14 will better support the corrosive action of the metal halides than the thinner outer wall The second embodiment of the invention, shown in Figure 2 includes a body portion 12 equal to the body portion of the embodiment of the invention shown in Figure 1 In addition, the second embodiment of the invention includes end pieces 50 that close the ends 22 and 24 of the body portion 12 and the end pieces are provided with legs 52 that support the electrodes, the tips of which are disposed within the space 20 surrounded by the external wall 14 of the body portion 12. Also, the end pieces 50 include closing walls 54 arranged in axial fashion of the longitudinal boundary of the outer wall 14 and the walls of the body. They are thicker than the thickness of the external wall. A difference between the modality of Figure 1 and the modality of Figure 2 is the configuration of the inner surface of the closure wall In the embodiment of Figure 2, the interior surface of the closure wall has a curvilinear profile and the curvilinear profile 56 of the interior surface of the closure wall extends inwardly from the interior surface 18 of the wall 14 continuous external, relative to the space 20 surrounded by the outer wall of the body portion 12 and downward, when the ceramic arc chamber 10 is arranged for use In this way, the line of fusion between the inner surface of the closure wall and the interior surface of the continuous external wall does not provide sharp edges, where a minimum temperature can be established. In addition, a transition area 55 between the interior surface of the closure wall and the wall from opening 53 in leg 52 is curvilinear Due to the end of the arc chamber adjacent to the first end of the continuous external wall, sharp edges are avoided, and corrosive effects are minimized Metal halides will tend to collect on the interior surface of the closing wall in a thin layer over a large surface area, and in the embodiment of Figure 2, which is essentially where the closing wall is thicker. The third embodiment of the invention, shown in Figure 3 includes a body portion 12 as well as the body portions of the embodiments of the invention shown in Figures 1 and 2 However, the lengths of the body portion 12 of the embodiment of Figure 3 are a little shorter than the lengths of the body portions 12 of the embodiments of Figures 1 and 2 for the following reasons. The third embodiment of the invention also includes end pieces 58 that close the ends of the portion. 14 of body and end pieces are provided with legs 60 to support the electrodes, the tips of which are disposed within the space 20 surrounded by the external wall 14 of the body portion 12. In addition, the end pieces 58 include walls 62. of closure arranged axially of the longitudinal limit of the outer wall 14 and the closing walls 62 are thicker than the thickness of the outer wall 14 A difference between the embodiment of Figure 3 and the embodiment of Figure 2, by a part, and the embodiment of Figure 1 on the other hand, is the configuration of the interior surface 64 of the closure wall 62. In the embodiment of Figure 3, the interior surface 64 of the closure wall 62 has a spherical configuration extending inwardly from the interior surface 18 of the continuous external wall 14, relative to the space 20 surrounded by the external wall 14 of the body portion 12 and downwardly when the ceramic arc chamber is arranged for use As with the embodiment of Figure 2, the condensed metal halides will tend to be collected on the interior surface 64 of the closure wall, when the closure wall is essentially thicker since the end pieces are free of edges sharp, such as wherein the interior surfaces of the outer wall and the closing wall are fused and wherein the inner surface of the closing wall joins the wall of the opening in the leg 60, which promotes corrosion. Further distinctive of the embodiment of Figure 3 is that the outer surface 66 of the closure wall has an essentially conical configuration. This configuration provides benefits related to maneuverability, fabrication and corrosion. The spherical configuration of the interior surface 64 of the wall 62 of closure provides additional volume within the arc chamber of the embodiment shown in Figure 3 as a result and because it may be convenient to maintain the internal volumes of the three arc chambers approximately equal, the length of the body portion 12 of the embodiment of Figure 3 is shorter than the lengths of the body portion 12 of the modes of Figs. 1 and 2 in that case The characteristic of the embodiments of Figures 2 and 3, whereby the configuration of the inner surfaces 56 and 64 of the closing walls are free of sharp edges, results in the establishment of a thermal profile between the first end 22 and the second end 24 of the arc tube 10, which causes the metal halide additives to deposit substantially uniformly on the respective inner surfaces 56 and 64 of the part closing wall at the first end 22 of the external wall 14 of the body portion 12 of the arc tube 10 This facilitates the collection of metal halides away from the inner surface 18 of the outer wall 14 The configurations of the inner surfaces of the Closing walls of the embodiments of Figures 2 and 3 are examples of configurations having this property, but other configurations will be apparent to those skilled in the art with the same result. The characteristic of the embodiments of Figures 2 and 3, in wherein the inner surface 18 of the continuous outer wall 14 of the body portion 12 and the inner surface 56 of the closure wall 54 of the part 5 At the end, as well as the inner surface 64 of the closure wall 62 of the end piece 58, are configured to be fused in such a way that their melting line, not only provides any sharp edges and the transition areas between the edges. interior surfaces of the closure walls and the walls of the openings in the legs that support the electrodes that do not provide sharp edges, allow the invention to be applied in embodiments wherein the ceramic arc tube is arranged in any orientation between the vertical and horizontal and in embodiments wherein the closing wall of the end piece is not thicker than the thickness of the external wall of the body portion The deposition of the metal halides, as described, in particularly with reference to Figures 2 and 3, it occurs for the deposition to take place on an essentially uniform area. This results in improvements in the operation of the lamp due to the increased mass transport of the metal halides within the arc established between the electrodes In each of the embodiments of the invention, shown in Figures 1, 2 and 3, the outer surface 16 and the inner surface 18 of the continuous external wall 14 of the body portion 12 of the arc chamber 10 are illustrated as essentially cylindrical However, these surfaces may take other forms. For example, the surfaces may be spherical or oblong. The embodiments described above, in particular, the embodiments illustrated in Figures 2 and 3, may provide improvements in addition to those mentioned. , improvements can be obtained in I umens per watt, the color reproduction index and the correlated color temperature for the Vertical and horizontal orientation of the ceramic arc tube Although the invention has been described with respect to certain embodiments thereof, those skilled in the art will be able to recognize that the invention can be practiced with modifications that are within the scope and spirit of the invention. claims that follow For example, the ceramic arc chamber is not limited to a three-piece construction, but can be constructed of two, five or any number of pieces as can be understood by persons skilled in the art.

Claims (28)

1. CLAIMS A ceramic arc chamber for a discharge lamp characterized in that it comprises a body portion having a continuous external wall, which includes an outer surface and an inner surface and surrounding a space adapted to contain electrodes and the halide additives of metal, the continuous external wall includes a first end and a second end that are longitudinally spaced from one another and define the longitudinal boundary of the continuous external wall and at least the first end of the continuous external wall has an opening within the space that is surrounded by the continuous outer wall, and an end piece located in the opening at the first end of the continuous external wall and joined with the inner surface of the continuous external wall, the end piece has a wall of a closure which is generally arranged axially of the longitudinal limit of the continuous external wall and has an outer surface and an inner surface facing the space surrounded by the continuous outer wall, the inner surface of the continuous outer wall of the body portion and the inner surface of the closing wall of the end piece are configured to thereby merge into a such that its melting line and the interior surface of the closure wall do not provide sharp edges at the ends of the ceramic arc chamber adjacent to the first end of the continuous external wall. The ceramic arc chamber according to claim 1, characterized in that the closing wall of the end piece located in the opening at the first end of the continuous external wall has a greater thickness than the thickness of the continuous external wall. The ceramic arc chamber according to claim 1, characterized in that the inner surface of the closing wall has a curvilinear profile and the curvilinear profile of the inner surface of the closing wall extends inward from the inner surface of the wall. the outer wall continues, in relation to the space surrounded by the external wall of the body portion and far from the space surrounded by the external wall of the body portion 4 The ceramic arc chamber according to claim 1, characterized in that the inner surface of the closure wall of the end piece has a spherical configuration extending inward from the sup inner surface of the continuous outer wall, relative to the space surrounded by the outer wall continuous and far from the space surrounded by the outer wall of the body portion 5 The ceramic arc chamber according to claim 4, characterized in that the surface The outer wall of the closing wall has an essentially conical configuration. The ceramic arc chamber according to claim 5, characterized in that the outer surface and the inner surface of the continuous outer wall are essentially cylindrical. conformity with claim 6, characterized in that the first end of the continuous external wall includes a terminal portion that forms the support for the end piece and the end piece includes a flange portion extending axially outwardly from the longitudinal limit of the wall The continuous arc chamber rests on the terminal portion of the continuous external wall. The ceramic arc chamber according to claim 7, characterized in that the end piece comprises an injection molded end part. according to claim 1, characterized in that the body portion is adapted to be configured, when in use, so that the longitudinal limit of the continuous external wall is positioned in such a way that the first end of the continuous external wall is located under the second end of the continuous external wall and the configuration of the internal surface of the closing wall is ta l which establishes a thermal profile on the first end of the ceramic arc chamber which causes the metal halide additives to deposit essentially in a uniform manner on the inner surface of the closing wall of the end piece 10 of ceramic arch in accordance with claim 9, characterized in that the inner surface of the closing wall is curvilinear in profile and the curvilinear profile of the inner surface of the closure wall extends inward from the interior surface of the continuous external wall, relative to the space surrounded by the wall outside of the body portion, and down when the arc chamber The ceramic arc chamber according to claim 10, characterized in that the inner surface of the closing wall of the end piece has a spherical configuration extending inwardly from the inner surface of the ceramic part. the outer wall continues, in relation to the space surrounded by the continuous external wall, and downwards when the ceramic arch chamber is arranged for its use The ceramic arc chamber according to claim 11, characterized in that the outer surface of the closing wall has an essentially conical configuration. The ceramic arc chamber according to claim 12, characterized in that the outer surface and the The inner surface of the continuous outer wall is essentially cylindrical. The ceramic arc chamber according to claim 13, characterized in that the first end of the continuous external wall includes a terminal portion that forms a support for the end piece and the part. end includes a flange portion extending axially outwardly of the longitudinal boundary of the continuous outer wall and resting on the terminal portion of the continuous outer wall. The ceramic arc chamber according to claim 14, characterized in that the end piece comprises an in-molding end part 16 A ceramic arc chamber for a discharge lamp, characterized in that it comprises a body portion having a continuous external wall that includes an outer surface and an inner surface and surrounding a space adapted to contain electrodes and metal halide additives, the continuous external wall includes a first end and a second end that are separated longitudinally of one another and define the longitudinal limit of the continuous external wall, the body portion is adapted to be arranged, during use, so that the longitudinal limit of the continuous external wall is positioned in such a way that the first end of the continuous outer wall is located below the second end of the continuous external wall, and at least, the first end of the continuous external wall has an opening within the space that is surrounded by the continuous external wall, and an end piece located in the opening at the first end of the continuous external wall and joined with an inner surface of the continuous external wall, the end piece has a closure wall which is arranged, generally, axially of the longitudinal limit of the continuous external wall, has a thickness greater than the thickness of the continuous external wall and has an outer surface and an inner surface which is confronted with the space surrounded by the continuous outer wall, the inner surface of the continuous external wall of the body portion and the inner surface of the closing wall of the end piece are configured so as to fuse together in a form for that the metal halide additives will accumulate essentially only on the inner surface of the closing wall and the harmful buildup of the metal halide additives against the inner surface of the wall will be prevented continuous external of the body portion of the ceramic arc chamber 17 The ceramic arc chamber according to claim 16, characterized in that each of the first end and the second end of the continuous external wall have an opening within the space which is surrounded by the continuous outer wall and the respective, similar end pieces are located in the openings so that the first end or the second end of the continuous external wall can be located under the other when the ceramic arc chamber is arranged for use 18 The ceramic arc chamber according to claim 16, characterized in that the inner surface of the closing wall includes an inclined portion and a portion that is arranged inwardly of the inclined portion., in relation to the space that is surrounded by the continuous outer wall and below the inclined portion when the ceramic arc chamber is arranged for use and the inclined portion essentially joins the interior surface of the continuous external wall with the portion of the inner surface of the closing wall, which is arranged inwardly of the inclined portion and below the inclined portion 19 The arc chamber according to claim 18, characterized in that each of the first and second end of the outer wall continues they have an opening within the space that is surrounded by the continuous external wall and the similar respective end pieces are located in the openings so that the first end or the second end of the continuous external wall can be located under the the other when the ceramic arc chamber is arranged for use. The arc chamber according to claim 16, characterized in that the inner surface of the closing wall of the end piece has a curvilinear profile and the curvilinear profile of the arc chamber. the inner surface of the closure wall extends inward from the inner surface of the continuous external wall, relative to the space surrounded by the outer wall of the body portion and downwardly when the ceramic arch chamber is arranged for its use 21 The arc chamber according to claim 20, characterized in that each of the first and second end of the continuous outer wall has an opening within the space that is surrounded by the continuous external wall and the respective respective end pieces are located in the openings so that the first end or the second end of the continuous external wall can be located under the other when the The arc chamber according to claim 16, characterized in that the inner surface of the closing wall of the end piece has a spherical configuration extending inwardly from the surface. interior of the continuous external wall, in relation to the space surrounded by the continuous external wall and downwards when the ceramic arc chamber is arranged for use 23 The arc chamber according to claim 22, characterized in that the outer surface of the closure wall has an essentially conical configuration 24 The arc chamber according to claim 23, characterized in that each of the first and second end of the continuous outer wall has an opening within the space that is surrounded by the continuous external wall and the similar respective end pieces are located in the openings so that the first end or the second end of the continuous external wall can be located under the other when the ceramic arc chamber is arranged for use. The arc chamber according to claim 16, characterized in that the configuration of the inner surface of the closing wall, it is such that a thermal profile is established between the first end and the second end of the arc tube which causes the metal halide additives to deposit substantially uniformly on the inner surface of the closure wall of the end piece 26 The arc chamber according to claim 25, characterized in that the inner surface of the closing wall has a profile that and the curvilinear profile of the inner surface of the closure wall extends inward from the interior surface of the continuous external wall, relative to the space surrounded by the external wall of the body portion and downward when the arch chamber of ceramic is arranged for use 27 The arc chamber according to claim 25, characterized in that the inner surface of the closing wall of the end piece has a spherical configuration extending inward from the inner surface of the wall continuous external, in relation to the space surrounded by the continuous external wall and downward when the ceramic arc chamber is arranged for its use The arc chamber according to claim 27, characterized in that the outer surface of the closing wall has an essentially conical configuration. The arc chamber according to claim 16, characterized in that the outer surface and the inner surface of the The continuous external wall is essentially cylindrical. The arc chamber according to claim 16, characterized in that the first end of the continuous external wall includes a terminal portion that forms a support for the end piece and the end piece includes a portion of flange extending axially outwardly of the longitudinal boundary of the continuous outer wall and resting on the terminal portion of the continuous external wall 31 The ceramic arc chamber according to claim 16, characterized in that the end piece comprises a injection molding end piece