Plasma lamp as radiation source in artificial weathering apparatus

Abstract

An apparatus (10; 20) for artificial weathering of samples, lightfastness testing (3; 13), or simulation of solar radiation. The apparatus (10; 20) includes a weathering chamber (1), an electrodeless lamp (4; 14) disposed within the weathering chamber (1), and a radio frequency source. The electrodeless lamp is filled with a composition that is luminescent in a plasma state, and the radio frequency source emits a radio frequency field into the lamp to generate luminescent plasma that emits radiation similar to the spectral characteristics of natural sunlight.

Description

Technical Field

[0001] This disclosure relates to an artificial weathering device, a lightfastness testing device, or a sunlight simulation device, which includes an electrodeless discharge lamp as a light source, the electrodeless discharge lamp generating luminescent plasma through radio frequency or microwave energy to provide visible light and / or infrared light and / or ultraviolet radiation. Background Technology

[0002] Artificial weathering or solar simulation devices are designed to estimate the lifespan of materials that are frequently exposed to natural weather conditions during use and are therefore affected by climatic factors such as sunlight, solar heat, and humidity. To simulate natural weathering as realistically as possible, the spectral energy distribution of the light generated in the device should closely approximate the spectral energy distribution of natural solar radiation; therefore, xenon radiators are used as the radiation source in such devices. Accelerated aging tests of materials are essentially achieved by subjecting material samples to infrared radiation that is more intense than under natural conditions, thus accelerating the aging process. In this way, the long-term aging of material samples can be predicted after a relatively short period.

[0003] The numerous material samples studied in artificial weathering devices consisted of polymeric materials. Their weathering was essentially caused by the ultraviolet component of solar radiation. The primary photochemical processes occurring during this process—the absorption of photons and the generation of excited states or free radicals—were temperature-independent. Subsequent reaction steps with polymers or additives were likely temperature-dependent, thus the observed material aging was also temperature-dependent.

[0004] In existing weathering testing instruments, xenon lamps are commonly used as the radiation source. Although xenon lamps are known to simulate the solar spectrum well, the radiation they emit has a relatively high infrared spectral component, requiring filters to suppress it and prevent overheating of the sample. Furthermore, commercially available xenon lamp radiation sources have a lifespan of only about 1500 hours.

[0005] Despite their drawbacks of being non-adjustable or only slightly adjustable, halogen lamps can still be used as radiation sources. The same applies to fluorescent lamps: they are also used as radiation sources in weathering testers, but they also suffer from a relatively short lifespan.

[0006] This disclosure is necessary for the above and other reasons. Summary of the Invention

[0007] This disclosure relates to an apparatus for artificial weathering, lightfastness testing, and solar radiation simulation of material samples. The simulation includes a support for fixing the sample to be analyzed, an electrodeless lamp, and a radio frequency (RF) source. The electrodeless lamp is filled with a composition that is luminescent in a plasma state, and the RF source radiates an RF field into the lamp to generate luminescent plasma that emits radiation similar to the spectral characteristics of natural sunlight.

[0008] High-intensity discharge lamps (HID lamps) are widely used in lighting due to their excellent luminous efficiency and color rendering. Typically, a discharge lamp has a transparent casing containing a gas that emits light when a discharge current passes through two electrodes. Electrodeless lamps, on the other hand, have transparent bulbs filled with appropriate components and heated using radio frequency or microwave energy.

[0009] Compared to electrode discharge lamps, electrodeless lamps tend to have a longer lifespan and maintain better spectral characteristics throughout their lifespan. Electrodeless lamps require an RF power supply but can use bulbs with very simple structures, eliminating the need for expensive glass-metal interfaces. Furthermore, electrodeless lamps can use a wider variety of luminescent materials compared to traditional discharge lamps. Sulfur, selenium, and tellurium are popular fillers, but their applications are limited to electrodeless lamps because they are chemically incompatible with metallic electrodes.

[0010] For general lighting applications, as well as for all fields requiring high efficiency and excellent spectral characteristics, such as photography, film recording, agriculture, optoelectronic equipment testing, and artificial weathering, electrodeless lamps are an excellent alternative to traditional HID lamps.

[0011] In the embodiments shown and described below, the bulb is spherical, wherein an RF source radiates an RF field into the bulb such that the RF field fills the space within the bulb in an optimal manner. In particular, the RF source may include a magnetron that emits microwave radiation in the open 2.45 GHz band.

[0012] According to one example of an electrodeless lamp, the lamp also includes a conductive housing surrounding the bulb. The housing can be implemented using a conductive sheet, a conductive layer, or a conductive mesh. When using a conductive sheet or layer, it is supported by a suitable transparent, translucent, or light-transmitting substrate on which a thin conductive layer is deposited. According to another example, the housing is connected to an RF source. More specifically, the RF source includes a waveguide-like output terminal, with the housing connected to the waveguide. As will be seen and described in the embodiments below, the waveguide may include a central conductor and an outer tubular conductor surrounding the central conductor. Both the central conductor and the outer tubular conductor extend from the main surface of the RF source along the bulb direction. The housing may be connected to the outer tubular conductor. In one example, a dielectric rod may be connected between the central conductor and the bulb outer wall. In another example, there is a blank space between the central conductor and the bulb outer wall, specifically without an element like a dielectric rod between them.

[0013] Based on one example of a lamp, the lamp's structure ensures that no standing waves of radiated electric fields are generated during normal operation.

[0014] According to one example of a lamp, the lamp does not contain an external reflective wall of a conductive housing, and in particular, it does not contain a reflective wall that may form a cavity, resulting in the formation of standing waves during normal operation of the lamp.

[0015] According to one example of the device, it includes an additional condenser in which a lamp can be positioned. The condenser may have reflective walls to focus the light generated in the lamp into a beam of desired aperture, which can then be directed onto a specific sample to be examined in a desired manner. Attached Figure Description

[0016] The accompanying drawings help to further understand the various aspects of the device and form part of this description. The drawings illustrate the various aspects and, together with the description, explain the principles of those aspects. Other aspects and their many anticipated advantages will become more readily understood by referring to the detailed description below. The elements in the drawings are not necessarily to scale. Similar reference numerals may indicate corresponding similar parts.

[0017] The present disclosure will now be explained in more detail with reference to the accompanying drawings, diagrams, and exemplary embodiments.

[0018] Figure 1 include Figure 1 A and Figure 1 B, and shows the vertical cross-section of the artificial weathering device. Figure 1 A and horizontal section top view Figure 1 B, the device is a dynamic type with rotating samples.

[0019] Figure 2 A cross-section of an example lamp assembly is shown, which also includes a conductive housing surrounding the bulb.

[0020] Figure 3 Another example of a lamp assembly is shown, in which a dielectric rod is connected between the central conductor and the outer wall of the bulb.

[0021] Figure 4 include Figure 4 A and Figure 4 B, and shows the vertical cross-section of the artificial weathering device. Figure 4 A and horizontal section top view Figure 4 B, the device is a static type with a fixed sample. Detailed Implementation

[0022] The accompanying drawings help to further understand the various aspects of the device and form part of this description. The drawings illustrate the various aspects and, together with the description, explain the principles of those aspects. Other aspects and their intended advantages will become more readily understood by referring to the detailed description below. The elements in the drawings are not necessarily to scale. Similar reference numerals may indicate corresponding similar parts.

[0023] The following detailed description is taken with reference to the accompanying drawings, which illustrate specific aspects of implementing this disclosure. In this regard, directional terms such as “top,” “bottom,” “front,” “rear,” etc., may be used with reference to the orientation of the described figures. Since the device components can be positioned in multiple different orientations, the directional terms are for illustrative purposes and are not restrictive. Other aspects may be utilized, and structural and logical changes may be made, without departing from the concept of this disclosure. Therefore, the following detailed description should not be considered restrictive, and the concept of this disclosure is defined by the appended claims.

[0024] Furthermore, a particular feature or aspect of this disclosure may be disclosed only in one of several embodiments, but such a feature or aspect may be combined with one or more other features of other embodiments, as long as it is desirable and advantageous for a given or particular application. Moreover, where the terms “comprising,” “having,” “having,” or other variations thereof are used in the detailed description and claims, these terms are included in a manner similar to the term “constituting.” The terms “coupled” and “connected” and their derivatives may be used. It should be understood that these terms can be used to indicate that two elements or layers cooperate or interact with each other, whether they are in direct physical or electrical contact, or not in direct contact, i.e., one or more intermediate elements may be disposed between them. Furthermore, the term “exemplary” is for illustrative purposes only and not a best or optimal example. Therefore, the following detailed description should not be considered limiting, and the scope of this disclosure is defined by the appended claims.

[0025] Figure 1 include Figure 1 A and 1B, and show an apparatus for artificial weathering of samples according to this disclosure.

[0026] Figure 1 The apparatus 100 includes a weathering chamber 1 and a mounting frame 2, which, after installation, is capable of rotating within the weathering chamber 1. The mounting frame 2 is in the form of a closed loop, and the sample 3 or workpiece can be fixed to a suitable mounting platform or socket on the mounting frame 2. In particular, the mounting frame 2 can have a cylindrical shape and a circular cross-section, such as... Figure 1 As shown in B.

[0027] Figure 1The apparatus 100 also includes an electrodeless lamp 10 disposed in the weathering chamber 1, the bulb of which is filled with a composition that emits light in the plasma state, and an radio frequency source 12. The radio frequency source 12 radiates a radio frequency field 13 into the bulb 11 to generate luminescent plasma, which emits light radiation 15 that is equal to or similar to the spectral radiation characteristics of the natural sun.

[0028] After the electrodeless lamp 10 is installed, its central axis coincides with the cylindrical axis of the mounting bracket 2. Furthermore, the mounting bracket 2 can rotate such that its rotation axis coincides with both the cylindrical axis and the central axis of the electrodeless lamp 10. As a result, when the mounting bracket 2 is rotated, the sample 3 moves along a circular path around the electrodeless lamp 10, ensuring that the distance between the sample 3 and the lamp 10 remains constant and does not change over time.

[0029] In a manner known per se, the weathering chamber 1 may also have other artificial weathering devices, such as a humidity generator. Since they do not play a significant role in this disclosure, they will not be discussed further. For example, an airflow may also be blown into the weathering chamber 1 and swept vertically across the sample 3.

[0030] like Figure 1 As shown in the example, bulb 11 is spherical. However, the bulb can also be an elongated shape comprising two opposite ends, with an radio frequency source located at one end.

[0031] The bulb 1 can be filled with a chemical composition that, when ionized and heated to a plasma state, is suitable for producing light. Several compositions can be used as fillers within the framework of this disclosure in an inert atmosphere, including mercury, sulfur, selenium, tellurium, metal halides, and mixtures thereof. For example, the composition may contain mercury and one or more of the other aforementioned components. The composition may contain more than just mercury. Furthermore, the composition should ensure that the radiation emitted by the lamp approximates the spectral characteristics of solar radiation. Otherwise, this disclosure is not limited to a specific chemical composition.

[0032] Any transparent material, as long as it can withstand the high temperatures and internal pressures reached during lamp operation and is chemically compatible with the filler components, can be used to manufacture the bulb 11. Typically, the operating temperature of the bulb 11 is in the range of 600-900°C, while the internal pressure of the working chamber ranges from 0.1-2 MPa. For example, fused silica (i.e., fused silicon dioxide) can be used as the material for the bulb 11.

[0033] Depending on the desired power of the emitted radiation, the volume of bulb 11 can range from 0.5 to 100 cm³. 3 Between 10-30cm 3 between.

[0034] Figure 1Only one electrodeless lamp is shown in the weathering chamber. Two or more lamps can also be installed in the weathering chamber.

[0035] Figure 2 A partial longitudinal sectional view is shown as another example of an electrodeless lamp assembly in a weathering device.

[0036] like Figure 2 As shown, the electrodeless lamp 20 may also include a conductive housing 24 surrounding the bulb 21. (As...) Figure 2 As shown, the conductive outer shell 24 can be in the form of a conductive mesh. The outer shell 24 can surround the bulb 21, such that the outer shell 24 is symmetrical about the cylinder, and the central longitudinal axis of the bulb 21 coincides with the central cylindrical axis of symmetry of the outer shell 24.

[0037] The outer casing 24 may also be in the form of a suitable transparent, translucent or light-transmitting substrate on which a thin and transparent conductive layer is disposed.

[0038] The lateral diameter of the outer casing 24 can be in the range of 5-30 cm, and in particular, it remains constant throughout its entire length.

[0039] More specifically, such as Figure 2 The discharge lamp 20 shown has a bulb 21 filled with a component that emits light in a plasma state. The discharge lamp 20 also includes a radio frequency (RF) source 23 that radiates an RF field 23.1 to the lower end of the bulb 21. The RF source 23 may include a magnetron that emits in an open 2.45 GHz band. The discharge lamp 20 also includes a metal mesh 24 arranged around the bulb 21 such that the bulb 21 and the metal mesh 24 are cylindrically symmetrical and share a common cylindrical axis. The RF source 23 includes or is connected to a waveguide 26, which forms an output end on the upper surface of the RF source 23 that outputs microwave radiation. The waveguide 26 is similar to a coaxial transmission line and includes a central conductor 26.1 and an outer conductor 26.2 that surrounds the central conductor 26.1 in a sleeve-like manner. The lateral diameter of the waveguide 26 can be in the range of 5-30 cm, and the lateral diameter of the outer shell 24 can be the same as that of the waveguide 26. The lateral diameter of the central conductor 26.1 can be in the range of 1-10 cm and can be substantially the same as the lateral diameter of the bulb 21. The length of waveguide 26 can be in the range of 2-10 cm.

[0040] like Figure 2 As shown, the outer casing (particularly mesh 24) can be connected to the outer tubular conductor 26.2 of the waveguide 26, thus having essentially the same lateral diameter. Mesh 24 serves to confine the radio frequency field. No elements are disposed between the upper surface of the center conductor 26.1 and the lower surface of the bulb 21.

[0041] Figure 3 A longitudinal sectional view of the lower part of the discharge lamp 30 is shown.

[0042] like Figure 3 The discharge lamp 30 shown includes a bulb 31, an RF source 32, a metal mesh 34, and a waveguide 36, all of which are configured to be similar to... Figure 2 The discharge lamp 20 is the same. However, as an additional element, a dielectric rod 37 is disposed between the center conductor 36.1 of the waveguide 36 and the bulb 31. The waveguide 36 may include a metal cup 36.3 covering the center conductor 36.1, and has a central opening on its upper surface into which the dielectric rod 37 is inserted. The dielectric rod 37 extends from the opening or the upper surface of the center conductor 36.1 through the opening to the lower surface of the outer wall of the bulb 36.1. In this way, the electric field is almost completely guided through the dielectric rod 37, and the dielectric rod 37 acts as a dielectric waveguide, directly guiding microwave energy into the internal volume of the bulb 31. Therefore, as shown by the electric field line 33.1, and Figure 2 Compared to the discharge lamp 20, the channel for the electric field to enter the bulb 31 can be improved.

[0043] exist Figure 2 and Figure 3 In both examples of electrodeless lamps, the radio frequency (RF) source is entirely located outside the bulb and radiates the RF field from the outside into the bulb. However, it is also possible to integrate at least part of the RF source into the bulb, for example, by inserting a center conductor through an opening in the bulb wall into the bulb.

[0044] like Figure 1 , 2 The electrodeless lamp startup shown in any of Figures 1 and 3 can be performed in two steps. First, when the lamp is started, due to Pascal's law, a low-pressure discharge inside the bulb produces ultraviolet light. This discharge is mainly controlled within the rare gas in the bulb. The remaining active materials remain in a solid or liquid state. Then, this discharge heats the other active materials. The discharge consists of low-ionized molecules, and the temperature is still too low to ionize the molecules. When the temperature inside the bulb reaches a certain level, the remaining active materials will evaporate. At this point, these substances are mixed in the discharge. The discharge changes the behavior of the matter, transforming it into thermal plasma. At this point, the discharge impedance changes and matches the rest of the system. The reflection of microwave radiation is greatly reduced, and power can be transferred to the discharge to produce a large amount of light. Compared to the beginning of the discharge (the first 10-15 seconds), the discharge composition is completely different; at this point, the evaporated molecules are the majority, and the rare gas molecules used to initiate the discharge are a minority (less than 1%).

[0045] Figure 4 include Figure 4 A and Figure 4 B, and shows a static artificial weathering device with a fixed sample.

[0046] like Figure 4 The artificial weathering device 200 shown includes a weathering chamber 201, on the bottom surface of which multiple samples 3 or workpieces can be arranged. Figure 4 The device 200 also includes an electrodeless lamp 210 and a radio frequency source 212 disposed in the weathering chamber 201. The bulb 211 of the electrodeless lamp 210 is filled with a composition that can emit light in the plasma state, and the radio frequency source 212 radiates a radio frequency field 213 into the bulb 211 to generate luminescent plasma for emitting light radiation 215 similar to the spectral radiation characteristics of the natural sun.

[0047] The electrodeless lamp 210 also includes a condenser 214 that focuses the light generated in the bulb 211 into a beam of desired aperture, which is then directed onto the specific sample to be inspected. Figure 4 In the example, the concentrator 214 is a conical light reflector 214 with a reflective inner wall, used to collect as much light as possible emitted by the bulb 211 and guide it onto the sample 203, as shown by the arrow.

[0048] Furthermore, the device 200 and the electrodeless lamp 210 may include the above. Figure 1 Device 100 or Figure 2 and Figure 3 No characteristics of electrodeless lamps.

[0049] This disclosure has shown and described one or more implementations, but at least some equivalent changes and modifications will be made by others skilled in the art based on a reading and understanding of this description and the accompanying drawings. This disclosure includes all such modifications and changes and is limited only by the following claims. In particular, with respect to the various functions performed by the aforementioned components (such as elements, resources, etc.), unless otherwise stated, the terminology describing these components is intended to correspond to any component that performs a specific function of said component (e.g., functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the function in this exemplary implementation. Furthermore, a particular feature of this disclosure may be disclosed only in one of several embodiments, but this feature may be combined with one or more other features of other embodiments, as long as it is desirable and advantageous for a given or particular application.

Claims

1. An apparatus (100; 200) for artificial weathering or lightfastness testing of a sample (3; 203), or for simulating solar radiation, the apparatus (100; 200) comprising: - Weathering chamber (1; 201); - An electrodeless lamp (10; 210) is installed in the weathering chamber (1; 201), and includes - The light bulb (11; 211) is filled with a composition that emits light in the plasma state, and - The radio frequency source (12; 212) radiates a radio frequency field (13; 213) to the bulb (11; 211) to generate radiation (15; 215) that is similar to or equivalent to the radiation characteristics of the natural solar spectrum; The electrodeless lamp (10; 210) also includes a conductive housing (24; 34) surrounding the bulb (21; 31); the radio frequency source (23; 33) includes a waveguide (26; 36) as a guide for radio frequency waves, wherein The housing (24; 34) is connected to the waveguide (26; 36); the waveguide (26; 36) includes a center conductor (26.1; 36.1) and an outer tubular conductor (26.2; 36.2) surrounding the center conductor (26.1; 36.1), the center conductor (26.1, 36.1) and the outer tubular conductor (26.2; 36.2) extending from one of the main surfaces of the RF source (23; 33) along the direction of the bulb (11, 21); it also includes A dielectric rod (37) is connected between the surface of the central conductor (36.1) and the outer wall of the bulb (31).

2. The apparatus (100; 200) according to claim 1, wherein The light bulb is filled with a gas containing one or more of mercury, sulfur, selenium, tellurium, and metal halides.

3. The apparatus (100; 200) according to claim 2, wherein The gases include mercury, and one or more of sulfur, selenium, tellurium, and metal halides.

4. The apparatus (100; 200) according to claim 2 or 3, wherein The gas contains more than just mercury.

5. The apparatus (100; 200) according to claim 2, wherein Gases exist in an inert atmosphere.

6. The apparatus (100; 200) according to claim 1, wherein The outer shell (24; 34) is connected to the outer tubular conductor (26.2; 36, 2).

7. The apparatus (200) according to claim 1, further comprising: An electrodeless lamp (210) equipped with a condenser (214).

8. The apparatus (200) according to claim 7, wherein The concentrator (214) includes a reflector wall for focusing the light generated in the bulb (211) into a beam of light with the desired aperture.

9. The apparatus (100) according to claim 1, wherein The sample (3) can be rotated around the electrodeless lamp (10).

10. The apparatus (200) according to claim 1, wherein The device arranges the samples (203) in a fixed manner.

11. The apparatus (100; 200) according to claim 1, wherein at least a portion of the light radiation (15; 215) from the electrodeless lamp (10; 210) in the apparatus (100; 200) falls directly onto the sample (3; 203).

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