Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/52—Cooling arrangements; Heating arrangements; Means for circulating gas or vapour within the discharge space
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/30—Vessels; Containers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
  • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
  • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
  • H01J65/046—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by using capacitive means around the vessel

Definitions

• An object of the present invention is a discharge barrier lamp.
• the principle of such a lamp is described in the "Discharge Handbook", Elektrogesellschaft, June 1989, 7th edition, page 263. Its radiation is generated by a dielectric working fluid subjected to electrical discharges. Typically this fluid is a gaseous medium at low pressure consisting of a rare gas and / or a halogen. Under the effect of a discharge, it forms excited species whose radiative electronic de-excitation transitions generate radiation to be emitted. These excited species are typically "excimer” or “exciplex” type molecules. The lamp then emits a particularly monochromatic ultraviolet radiation. The working fluid is confined in an ampoule whose walls are typically made of vitreous silica.
• These walls form two coaxial tubes constituting an inner tube and an outer tube, and this fluid is confined in the annular space between these two tubes.
• Electrical discharges are typically caused by steep high voltage pulses. Typically these pulses have a maximum voltage of several kilovolts and they last a few hundred nanoseconds and are repeated at a frequency of a few tens or hundreds of kilohertz. They are applied between on the one hand an internal electrode located in the inner tube of the bulb and connected and on the other hand an external electrode applied around the outer tube. The walls of these two tubes then constitute two dielectric discharge barriers. Only the internal electrode is brought to a high voltage.
• Such an ultraviolet lamp can be used for example in photochemistry or for industrial surface treatments, and also in medicine, especially in dermatological treatments such as psoriasis or vitiligo. Electrical discharges generated in the working fluid can excessively heat up this fluid. It is widely recognized that efficient cooling of this fluid is an essential condition of the longevity of the performance of such a lamp. This was confirmed by the work of the High Current Electronics Institute, a branch of the Siberian Academy of Sciences of Russia, to which many of the present inventors. The difficulties in obtaining sufficient cooling increase with the power of the lamp and more particularly with the pfd of the radiative flux to be emitted.
• a first discharge barrier lamp is known from patent documents EP0517929 and CA2068574 (Von Arx).
• a second discharge barrier lamp is known and is referred to as "lamp I" by US6379024 (Kogure).
• the electrodes of this lamp have limited angular extents around the axis of the bulb so that only a portion of the working fluid is subjected to electric discharges.
• the necessary cooling is provided by water flowing in a conduit which extends into the inner tube of the bulb.
• a conduit may be used to electrically isolate the water from the inner electrode.
• it then has the disadvantage of limiting the effectiveness of heat transfer to water.
• the means for ensuring the circulation of water and maintaining the tightness of the circuits in such a lamp are heavy and bulky. This may be why the document mentions the possibility of using air instead of water. But it is clear that the pfd of the radiative flux emitted by such a lamp should be strongly limited if this lamp was to be cooled in the air.
• a third discharge barrier lamp is known from US2004004422 (Falkenstein).
• a heat pipe extends between on the one hand a hot part engaged in the inner tube of the bulb of this lamp and on the other hand a cold part located and cooled outside this tube.
• This conduit is a sealed tube in which a liquid evaporates in the hot part, the vapor condenses in the cold part, and the condensed liquid returns to the hot, for example by capillarity, to evaporate again. It allows to get out of the inner tube a power particularly large thermal. But it is effective only in a relatively narrow temperature range, and its effectiveness is limited by that of the transfer of heat from the working fluid to its hot part. In addition, a sufficiently powerful cooling system must be installed at its cold end and be compatible with correct electrical insulation.
• the present invention is intended in particular to enable: - to increase the pfd of the radiative flux emitted by such a lamp, - to limit the temperature of the working fluid so as to limit the decrease in lamp performance with the duration of service, - to limit the weight, the bulk and the maintenance cost of the lamp, - to make the lamp easily manipulated and, more particularly, portable, - to facilitate a correct electrical insulation of an internal electrode subjected to impulses high voltage, and, for this, to ensure sufficiently powerful cooling of the working fluid by air.
• This lamp comprises a heat evacuator disposed with the internal electrode in an internal channel of the bulb of this lamp.
• This evacuator is made of a thermally conductive metal and is in at least thermal continuity with the internal electrode so as to transmit heat transversely of this electrode to the cooling fluid. For this it extends transversely in this channel while remaining at a distance from the wall. It extends longitudinally over at least a major fraction of a longitudinal extent common to both electrodes.
• Figure 1 shows a view of a first lamp according to this invention in cross section relative to an axis of a bulb of this lamp, a spacer of this bulb is not shown.
• FIG. 2 represents a cross-sectional view on an enlarged scale of an inner tube of the ampoule of FIG. 1.
• FIG. 3 represents a cross-sectional view of an inner tube of a bulb of a second lamp according to FIG. this invention, with indication of the electrode positions of this lamp.
• FIG. 4 represents an axial sectional view of the bulb of the second lamp according to this invention, with indication of the electrode positions of this lamp.
• FIG. 5 represents a schematic perspective view of a first convection circuit in a first position of the bulb of FIG. 3.
• FIG. 6 represents a schematic perspective view of a second convection circuit in a second position of FIG.
• FIG. 7 represents a schematic perspective view of the assembly of the two convection circuits of FIGS. 5 and 6.
• a discharge barrier lamp emits a stream of ultraviolet radiation represented by two arrows such as arrow 1. Typically, it is formed in a housing 2 preferably made of metal or a metallized plastics material. internally. The radiation is emitted by a light bulb through a window F.
• This bulb is typically constituted by an inner tube T1 and a coaxial outer tube TO and consisting of a vitreous silica such as quartz sold under the reference GE214 or GE219 by the firm General Electric.
• a working fluid is typically a gas or gas mixture.
• the pressures of such gas mixtures are between 0.05 and 1 bar, preferably between 0.1 and 0.3 bar.
• the gas mixture will be composed of Xe and Cl 2 , in the volume proportion of 250/1, for a total pressure of 114 mmHg.
• the emitted radiation will then have a wavelength.
• the internal electrode El receives for this purpose high voltage pulses which are supplied by a generator 3, the external electrode EO being connected to the earth constituted by the housing 2.
• the voltage of these pulses is preferably between 1 and 15 kV, and more preferably between 7 and 11 kV and their repetition frequency is preferably between 30 and 150 kHz and more preferably between 70 and 110 kHz.
• the window F is constituted by a part of the external electrode EO, only this part being transparent, or at least semi transparent, for the emitted radiation.
• this electrode surrounds the outer tube TO 360 degrees.
• it preferably comprises two unrepresented metal layers.
• An inner layer is for example constituted by a sheet of aluminum or an alloy of Al and Mg 100 .mu.m thick wrapped around the tube TO. This sheet has a width for example equal to the perimeter of the outer tube plus 1 to 5 mm to perform a slight recovery of the sheet. It has been cut beforehand to form the window F.
• a transparent layer is constituted by, for example, a wire wound helically with non-contiguous turns around the inner layer, and clamped on this inner layer.
• This wire is for example a nichrome wire 0.1 mm in diameter and is wound with a pitch of about 0.7 to 1 mm between each turn.
• the inner layer and this wire are held in contact with the tube TO by two circular flanges. This inner layer and these flanges are not shown and the portion of this wire which constitutes the window F is symbolically represented in FIG. 1 by a dashed line.
• the external electrode may further comprise a sheet EO which is shown in Figure 1and which maintains the bulb in the housing 2 by two extensions such as 6 which join the wall of this housing. The internal surfaces of the two electrodes and these extensions are processed to reflect the radiation emitted by the bulb so as to reinforce and uniform the flux emitted by the lamp.
• the heat from the electric discharges is evacuated by the air flowing in the tube T1 and around the external electrode E0.
• This air is driven by one or preferably two fans such as 4 arranged at both ends of the TT bulb. It enters the housing 2 and exits through openings such as formed in the walls of this housing.
• Figures 3 and 4 show the axis LA of the bulb TT and the angular extents Al, AO, and AF and longitudinal L1, L0 and LF of the electrodes E1 and E0 and the window F, respectively.
• the dimensions of the bulb and these areas are chosen according to the use envisaged for the lamp. The same is true of the composition and the pressure of the working fluid and the characteristics of the pulses supplied by the generator 3.
• the length LC of the space VC inside the bulb TT is preferably between 10 and 2000 mm. and more preferably between 100 and 200 mm.
• the diameter of the inner tube T1 is preferably between 10 and 50 mm, and preferably still close to 20 mm.
• the diameter of the outer tube TO is preferably between 20 and 100 mm, and preferably still close to 43 mm.
• the thickness of these tubes is preferably between 1 and 3 mm, and more preferably close to 1.5 mm.
• the distance between the outer surface of the inner tube and the inner surface of the outer tube is preferably between 5 and 25 mm, and more preferably close to 10 mm.
• a lamp according to this invention may have various shapes and arrangements.
• This wall is at least partially dielectric and at least partially transparent for the radiation.
• Two electrodes El and EO arranged outside the bulb and extending mutually opposite on either side of a fraction of the confinement space. This fraction constitutes a discharge space VD.
• the discharge space is limited to this fraction of extent. That is, the extent of the discharge space is the extent common to both electrodes.
• the wall of the bulb forms for the working fluid at least a first and a second circulation lanes W1 and W2 having a common part constituted by the discharge space. Each of these channels is capable of channeling a circulation of this fluid.
• first B1 and a second B2 looping spaces It passes for this by a space looping this way and respectively constituting a first B1 and a second B2 looping spaces. It offers the molecules of the working fluid a multitude of possible paths. In this multitude, an average path defines for the circulation of this fluid in this way a closed average linear circuit.
• the two such circuits respectively constitute a first and a second convection circuit. These two channels can not be accurately represented, they are represented in the form of these circuits W1 and W2.
• the first and second convection circuits extend respectively into first and second mutually crossed loopback surfaces P1 and P2. These surfaces are typically substantially planar and mutually perpendicular and the two loopback spaces typically have a second common portion PC away from the discharge gap VD.
• Each of the two circulation lanes W1 and W2 has a passage section for the fluid at each point of the convection circuit associated with it. way.
• This section has an area and all areas of the passage sections of that route include a minimum area and an average area. This minimum area is preferably greater than 30% of this average area.
• the lamp is preferably steerable in several directions so that the circulation of the working fluid is established preferably in one or the other of the two traffic lanes W1 and W2 in the direction of orientation of this lamp.
• This circulation is a convection circulation. It is caused by heating of this fluid in the discharge space VD and by its cooling in the looping space B1 or B2.
• Some of the areas of the bulb wall preferably surround the VC containment space and form TO peripheral wall areas.
• This channel has two ends C1 and C2 and an axial line LA extending between these two ends. It has a cross section at each point of this length and this cross section has an area and a perimeter. Still others of these wall areas connect these peripheral wall areas to these inner wall areas and form connecting wall areas. Lengths L1, L0 and LF and two mutually opposite longitudinal directions are defined along this axial line. Two mutually opposite transverse directions VD PC and PC VD are defined with respect to this line. Al, AO and AF perimeter ranges are defined around this line. An electrode is disposed in this channel in contact with at least one inner wall zone and constitutes an internal electrode El.
• the other electrode extends in contact with at least one peripheral wall zone and constitutes an external electrode E0.
• the discharge space VD has a perimetric extent A1 substantially less than one complete revolution, so that a remaining part of this turn constitutes the first looping space B1 and the first convection circuit W1 is extends over the whole of this round around the internal channel.
• this circuit is active, that is to say that the first channel W1 is the seat of a convective circulation, when the axis of the bulb is approximately horizontal, provided of course that the window F, under which the discharges occur and therefore warming, is not directed upwards.
• This circuit extends in a vertical plane perpendicular to the axis of the bulb. The circulation extends with a single direction of rotation but with a gradually decreasing speed, until the vicinity of the ends of the tubes T1 and TO.
• the discharge space has a length L 1 extending between two longitudinal ends D 1 and D 2 of this space and the confinement space has a length LC extending between two longitudinal ends C1 and C2 of this space. space.
• a gap extends between each of the two longitudinal ends of the discharge space and the closest of the two longitudinal ends of the confinement space.
• the two such intervals constitute a loopback interval C1 D1 and a loopback interval D2 C2.
• the second convection circuit W2 then includes in succession from this discharge space: a first segment S1 extending in a first longitudinal direction C1 C2 and constituted by a first looping interval; a second segment S2 consisting of two branches 2R, 2L extending in parallel on either side of the internal channel according to an average of a first transverse direction VD 1 PC in the length of the first looping interval, - a third segment S3 extending in the second longitudinal direction C2 C1 in a fraction of the confinement space transversely opposite the discharge space, a longitudinally median portion of this transversely opposite fraction constituting a common portion PC at the first and second looping spaces, - a fourth segment S4 consisting of two branches 4R, 4L extending in parallel on either side of the internal channel on average the second direction transve PC resale, VD in the length of a second loopback interval, and - a fifth segment S5 extending in the first longitudinal direction and constituted by the second loopback interval, and - a sixth segment S6
• this circuit is active, that is to say that the second channel W2 is the seat of a convective circulation, when the axis of the bulb is approximately vertical, and that whatever then the position of the window F.
• FIG. 7 schematizes the relative positions of the circuits W1 and W2 with respect to the bulb.
• the axis of this one is supposed to be vertical like the segment S3. That is, compared to the position of Figure 5, the bulb is assumed to have tilted 90 degrees.
• the circuit W2 In the position of Figure 7 only the circuit W2 is active. It extends in an axial plane, so vertical P2.
• the circuit W1 is only virtual. Its plane was vertical in Figure 5 but the tilting of the bulb makes it appear in Figure 7 as extending in a horizontal plane P1.
• Each loopback interval preferably has a length LB greater than 15% and more preferably 20% of the length LC of the confinement space VC.
• the axial line LA is preferably rectilinear. It then constitutes an axis of the TT bulb.
• the peripheral wall zones and internal wall zones constitute respectively an outer tube TO and an inner tube T1. These two tubes are typically transparent and dielectric over their entire surface. They are for example cylindrical and coaxial, the previously mentioned perimeter tracts then being angular extents.
• the window F is defined by a diaphragm. It is constituted by the opening of this diaphragm. Its longitudinal and angular dimensions are advantageously less than those of the discharge space VD so that only a central fraction, and preferably a majority, of the flux emitted by the working fluid is transmitted to an external target through this window.
• the stream received by this target can then be homogeneous, which is useful in many applications, whereas it would not be if it consisted of the entire flow emitted by the working fluid.
• the external electrode EO is advantageously present in the emission window F. It is then transparent, at least partially, for the radiation of the lamp. It is opaque around this window to constitute the diaphragm that defines this window. Its longitudinal and angular ranges are then greater than those of the internal electrode El so that it is the latter which defines the extent of the discharge space VD.
• the angular extent A1 of the discharge space VD is preferably between 5 and 180 degrees, and more preferably between 90 and 180 degrees.
• Its longitudinal extent L1 is preferably between 60% and 70% of the length LC of the confinement space.
• the angular AF and longitudinal LF extents of the window F are preferably between 70% and 90%, and more preferably between 80% and 90% of those A1 and L1 of the discharge space VD.
• the angular extent AO and lengthwise LO of the outer electrode E0 are preferably between 110% and 130%, and more preferably between 110% and 120% of those A1 and L1 of the discharge space VD.
• the lamp further comprises a heat evacuator EV extending transversely in the internal channel C1 while remaining at a distance from the internal wall zones T1.
• This evacuator is also made of a thermally conductive metal. and it is in at least thermal continuity with the internal electrode so as to transmit heat transversely of this electrode to the cooling fluid.
• the lamp preferably further comprises at least one dielectric spacer ET supported on internal wall regions remote from the internal electrode to maintain this electrode and / or the heat evacuator EV.
• This spacer is for example made of mica and it was glued to the inner tube after the establishment of the inner electrode and the heat evacuator.
• the inner electrode El and the evacuator EV are formed by the same piece of metal.
• this part is a longitudinally extending tube.
• the section of this tube comprises on the one hand an arc constituting the electrode El and on the other hand a rectilinear, convex or concave segment constituting the evacuator EV.
• the metal piece El, EV is a folded sheet with longitudinal fold lines. Folding is carried out so as to form contacts between the plies and the electrode and possibly unrepresented contacts between the successive folds.
• the heat evacuator EV is formed by a plurality of tubes such as EV1 and EV2 which extend longitudinally in mutual transverse contact.
• Tubes such as EV1 have a larger diameter than tubes such as EV2.
• the diameters and the number of these tubes are chosen to form a large number of contacts between the tubes and between the tubes and the electrode El, and for the spacer ET to ensure a permanent support force in most of the zones. contact.
• the advantageous arrangements indicated above make it possible to obtain efficient air cooling and thus to avoid the heaviness and bulk of water cooling. They make it possible to produce a portable and orientable lamp emitting a pfd remaining greater than 60 mW / cm 2 for more than 2000 hours. A practical embodiment of all the advantageous arrangements for cooling the lamp is shown in FIG.
• the internal electrode E1 and the heat evacuator EV are made of the same piece of metal, preferably aluminum, for example by direct machining of an aluminum block.
• the outer surface of the inner electrode E 1 has the shape of the inner surface of the inner tube T 1 with which it is in contact, typically cylindrical and with a diameter of a few tenths of a mm (typically 0.3 mm) smaller than the diameter of the surface.
• this surface of the inner electrode E1 has been polished (by manual or electrolytic polishing) and acts as a reflector for the UV rays emitted towards the center of the lamp.
• the central part of the electrode constitutes the heat evacuator EV, it consists of blades parallel to the flow of the cooling fluid and of the same length as the internal electrode El.
• the internal electrode El is held and angularly locked. and axially by a spacer ET of electronically and thermally insulating material (for example a MACOR ceramic).
• a spacer ET of electronically and thermally insulating material
• This configuration makes it possible to increase the heat exchange surface between internal electrode El and the cooling fluid.
• the ratio between this heat exchange surface and the surface of the inner tube T1 opposite the discharge zone is at least greater than two, and preferably four.
• the width of the blades is chosen to obtain a good conduction of heat from the outer face of the internal electrode El, heated by the discharges, to the heat exchange surfaces.
• This configuration also makes it possible to overcome the problems related to the differential expansion of the inner metal electrode El and the quartz bulb TT, since the expansion of the internal electrode El and its heat evacator EV is very evident. mainly between the blades of the heat evacuator EV, which strongly releases the mechanical stresses imposed on the inner tube T1 of the bulb TT during operation of the lamp. To achieve efficient cooling of the lamp, it is also important to promote the convection movements of the working gas. For this, the discharge volume VD must represent a minor fraction of the total volume of the working gas, typically between 10 and 50%, and must under no circumstances be on the upper part of this volume to avoid accumulating heat in the upper part of the TT bulb. In a preferred embodiment shown in FIG.
• the inner electrode E1 has a length L1 of about 90 mm, which represents about 60 percent of the total length LC of the confinement space VC (which is 150 mm in a preferred embodiment of the invention).
• its angular extent Al is 240 degrees which represents a discharge volume VD equivalent to 40% of the total volume of the working gas.
• the width LF of the window F being, in a preferred embodiment of the invention, 50 mm, and angular extent AF 180 °, this configuration ensures to have a very homogeneous power density on the surface of the emission window F of the radiation.
• a cooling means 4 a fan positioned in the axis LA of the inner tube Tl.
• the fan may be relatively compact, typically 40 * 40 * 10 mm3, and with a flow rate of at least 10m3 / h.
• it may be added a second fan, positioned at the other end of the inner tube T1 and whose flow is emitted in the same direction as the first fan (push-pull configuration).
• the discharge volume VD is located in the central zone of the bulb TT so that there exists, at any moment, a convection circuit W1 or W2 or a combination of W1 and W2 for thermalizing the gas regardless of the position of the lamp, the only exception being the horizontal position of the axis of the bulb TT with the window F directed upwards, which must absolutely be avoided, for the reasons given above ( convection is then frustrated).
• the existing devices for combating the treatment of psoriasis and vitiligo consisted of having a rather bulky generator 3 and a portable handpiece separate from its base. These devices have the major disadvantage of being bulky and relatively expensive to produce.
• One of the advantages of our invention is to compact the entire system.
• the entire system - lamp TT + cooling medium 4 + generator 3 + user interface - holds in a volume of less than two liters (typically 10 * 10 * 20 cm3).
• configuration shown in Figure 10 thus allows for an air-cooled portable lamp that can be manipulated in any position without special precautions. This is, to our knowledge, the first fully portable dielectric discharge barrier lamp, particularly suitable for dermatological treatments and other uses requiring frequent lamp movement.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Vessels And Coating Films For Discharge Lamps (AREA)
• Radiation-Therapy Devices (AREA)

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• 2005
  • 2005-06-02 WO PCT/FR2005/001361 patent/WO2006000697A2/fr active Application Filing
  • 2005-06-02 US US11/628,368 patent/US20080030115A1/en not_active Abandoned
  • 2005-06-02 EP EP05775232A patent/EP1774567A2/de not_active Withdrawn

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