JPH031779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a microwave-generated electrodeless source having improved spectral output in the ultraviolet region.

BACKGROUND OF THE INVENTION Electrodeless light sources are known and generally include a microwave chamber in which a lamp containing a plasma-forming medium is placed. For example, microwave energy generated by a magnetron is sent to the microwave chamber and complexed.
A luminescent plasma is excited through a physical mechanism.
The main component of the plasma forming medium contained within the lamp is typically mercury.

Electrodeless light sources should be distinguished from the most commonly used electrode arc lamps, which can be used to provide visible or ultraviolet radiation. Thus, an arc lamp comprises a gas-filled lamp having a pair of electrodes disposed within it, and when a potential difference is applied across the electrodes, an arc is generated between them which emits radiation. .

Problems to be Solved by the Invention Some characteristics of arc lamps and electrodeless lamps are significantly different, namely, arc lamps mainly generate light along the line between the electrodes, and electrodeless lamps generate light mainly along the line between the electrodes, and electrodeless lamps generate light mainly along the line between the electrodes, and electrodeless lamps Emits light from a nearby area. This occurs due to differences in temperature and electron density distribution. As a result, the heat load on the walls is higher in electrodeless lamps, which makes them more suitable for the use of additives with higher evaporation temperatures.

For electrodeless lamps such as those mentioned above, the ultraviolet range 300
It is desirable to make the spectral efficiency as high as possible in the range from 400 nm (nanometers).

Means for solving the problem It is therefore an object of the invention to provide improved efficiency and
An object of the present invention is to provide a microwave electrodeless light source device having a spectral output in the ultraviolet range of 300 to 400 nm.

According to the present invention, the improved light source device disclosed herein includes a means for generating microwave energy, a microwave chamber for receiving the microwave energy, and a material made of mercury and uranium halide. a lamp within the microwave chamber including a fill of

The invention will now be described with reference to the accompanying drawings.

EXAMPLE Referring to FIG. 1, an exemplary microwave electrodeless light source device is shown. It includes a lamp 2 filled with a plasma forming medium, typically mercury in a noble gas. The lamp 2 is placed in a microwave chamber 4, which includes a light reversal mirror 6 and a mesh 8 that is impermeable to microwaves but transparent to ultraviolet light.

In addition, FIG. 1 shows a magnetron 10 and a waveguide 1.
2 is shown. A magnetron 10 generates microwave energy, and this microwave is transmitted to a waveguide 1.
2 and is sent to the microwave chamber 4 through a coupling slot 14 in the microwave chamber wall. The microwave energy excites the medium within the lamp 2 to generate a plasma which emits ultraviolet light which passes through the mesh 8 and exits the light source. The operation of the lamp is at a relatively low pressure of about 1-5 atmospheres. Also shown in FIG. 1 are motor means 16 and related equipment for rotating the lamp for cooling purposes which do not form part of the invention. Additionally, although the exemplary configuration shown in FIG. 1 utilizes both a spherical lamp and a spherical microwave chamber, these are shown for illustrative purposes only; the microwave chamber may be e.g. It can be of various other shapes, cylindrical or parabolic.

The microwave electrodeless light source device shown in FIG. 1 must be clearly distinguished from the more commonly used mercury-arc lamps, since both the structure and the operating principle are different. Arc lamps include a lamp filled with gas at relatively high pressure and have a pair of electrodes therein. When a potential difference is applied across the electrodes, the gas therebetween ionizes, creating an arc discharge. The region between the discharge wall and the lamp wall is a cooler, with a neutral boundary layer of considerable thickness acting as a filter and absorbing some of the ultraviolet radiation emitted by the arc. Therefore, the operation of electrodeless lamps is based on different physical principles and different scientific regimes than arc lamps.
The spectral output that the fill constituents can produce in one type of lamp differs from the output that they can produce in another type of lamp, especially because of their respective effects in different parts of the radiation spectrum. Therefore, it cannot be predicted.

Effects of the Invention As mentioned above, conventional electrodeless lamps typically use a filling that is primarily mercury in a noble gas, and FIG.
in the infrared range as well as a small part of the visible range (400 to
5 is a graph showing the output power of such a lamp at 500 nm);

The table below is a representation of the incremental and accumulated power table illustrated in Figure 2 in the 300-400 nm UV range, and the total UV spectral power is approximately
Please note that it is 10 watts.

Interval (nm) Power Accumulated Power 300−310 15.35 15.35 310−320 27.63 42.98 320−330 4.93 47.91 330−340 7.20 55.11 340−350 2.97 58.08 350−360 2.41 60.49 360−370 32.01 92.50 370−380 3.64 96.14 380−390 2.73 98.87 390-400 2.58 101.45 According to the invention, the efficiency of an electrodeless lamp in ultraviolet light is substantially improved by the addition of uranium halide to the mercury filling.

FIG. 3 then shows the output power of the same lamp as shown in FIG. 2 but only with a lamp additionally containing uranium tetrachloride (UCl ₄ ) under approximately the same operating conditions as in FIG. (output
This is a graph of power). In fact, this
Fusion System in Rockville, Maryland
It is a spherical lamp manufactured by Corporation and is operated with a magnetron current of 670 ma.
Addition of uranium halide results in dramatic spectral improvement and increased efficiency in the UV light.

The table below is a tabular representation of the incremental and accumulated output power shown in Figure 3 and shows that the total accumulated power in the 300-400 nm UV range is approximately
210 watts, which represents more than a 100% increase in efficiency over lamps filled with mercury alone.

Interval (nm) Power Accumulated Power 300−310 10.40 10.40 310−320 12.50 22.90 320−330 12.20 35.10 330−340 18.00 53.10 340−350 22.50 75.60 350−360 2 8.40 104.00 360−370 30.70 134.70 370−380 26.90 161.60 380−390 26.00 187.60 390−400 23.50 211.10 The main mechanism by which electrodeless lamps produce ultraviolet light is by stimulation of atoms by electron bombardment, and uranium halides contain many electrons that are available for excitation. It is believed that the addition of uranium halide results in an increase in efficiency. Therefore, in an attempt to increase the efficiency of conventional electrodeless lamps, the inventor employed uranium halides based on his observation that uranium is the heaviest of all stable elements. Since uranium itself has a very high vaporization point, uranium halides, which have a lower vaporization temperature, were used. Applicant's belief that heavy elements will result in high spectral output in the ultraviolet range when activated within the electrodeless environment of the lamp of the present invention results in a high spectral output in the ultraviolet range, as shown in FIG. This appears to be corroborated by the spectral output.

According to a preferred embodiment of the invention, from 3 to 10
A lamp with an internal volume of cc is filled during manufacture with a volume of 0.2 ml of liquid mercury in a noble gas such as argon and a few mg of _UCl4 . Furthermore, a small amount of HgCl ₂ is added to keep the plasma away from the lamp wall and create an even boundary layer.
is added. Microwave power, over a power density range of several hundred watts/cc, is coupled to the lamp to provide ultraviolet spectral output, as shown in FIG.

Thus, improved efficiency in the ultraviolet light as well as a quasi-continuum in that range.
An ultraviolet lamp with a spectral output has been disclosed.

Although exemplary embodiments of the invention have been described, many modifications thereof will occur to those skilled in the art, and the invention is limited only by the claims appended hereto and their equivalents. It should be understood that this is limited.

[Brief explanation of the drawing]

FIG. 1 is a schematic representation of an embodiment of the invention. FIG. 2 is a graphical representation of the spectral output of a conventional electrodeless lamp light source using a mercury filling. FIG. 3 is a graphical representation of the spectral output of an electrodeless lamp light source according to the present invention. 2...Lamp, 4...Microwave chamber, 6...Light reflecting mirror, 8...Mesh, 10...Magnetron.

Claims (1)

[Scope of Claims] 1. In a microwave electrodeless light source device that generates a quasi-continuous spectrum in a predetermined ultraviolet spectral region, a microwave energy generating means, the microwave energy generated by the microwave energy generating means is supplied. a microwave chamber having an opening covered with a mesh that transmits ultraviolet rays but not microwaves; and a lamp disposed within the microwave chamber. A microwave radioisotope, characterized in that the forming filling contains mercury and a sufficient amount of uranium halide to interact with the mercury to generate a quasi-continuous spectrum in a predetermined ultraviolet spectral region. Electrode light source device. 2. The microwave electrodeless light source device according to claim 1, wherein the lamp has an internal volume of 3 to 10 c.c. and is filled with several mg of the uranium halide. 3. On page 1 or paragraph 2 of the claims,
A microwave electrodeless light source device, wherein the uranium halide is _UCl4 .