JPH0979905A - Emission spectrochemical analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the lower sample light detecting limit of an emission spectrochemical analysis device at a low level by effectively radiating the heat of the photomutiplier tube of the detecting section of the analysis device so that the tube can be cooled effectively without increasing the size of the detecting section. SOLUTION: A cathode cooling plate 11a which is thermally connected to the cathode of a photomultiplier tube 11 is fitted to the tube 11 and the plate 11a is thermally connected to part of an enclosure 13 through a Peltier effect element 15 so that the tube 11 can be forcibly cooled by the element 15 which radiates heat from the tube 11 to the outside through the enclosure 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emission spectroscopic analysis device, and more particularly to a structure for cooling a detection unit that receives a spectroscopic sample light.

[0002]

2. Description of the Related Art As shown in FIG. 5, an emission spectroscopic analyzer includes a light emitting section 1 for emitting light from a sample, a spectroscopic section 2 for separating the sample light from the light emitting section 1, and a spectroscopic section 2. And a detector 3 for receiving the sample light.

In the light emitting section 1, the sample light is generated by, for example, converting the sample into plasma by the plasma torch 4. The spectroscopic unit 2 disperses the sample light from the light emitting unit 1 by the mirror 5 and the diffraction grating 6. The detector 3 is usually composed of a side-on type photomultiplier tube 7, and this photomultiplier tube 7 is, as shown in FIG. 6, a housing 8 made of a heat conductive metal such as copper. It is housed inside. Note that reference numeral 9
Is a socket of the photomultiplier tube 7 and is attached to the housing 8.

[0004]

The photomultiplier tube 7 needs to be kept at a low temperature because the dark current increases as the temperature rises and the lower limit of light detection increases. In the detector 3 of the emission spectroscopic analyzer, the photomultiplier tube 7 is housed in the copper casing 8 as described above, and the generated heat is radiated to the outside through the casing 8. However, if the photomultiplier tube 7 is simply set in the copper casing 8,
There is a dislike that heat is not sufficiently radiated, and when the usage time is long, the temperature of the photomultiplier tube 7, especially the cathode electrode, rises, and the dark current increases. The sample light could not be detected.

According to the present invention, the lower limit of detection of the sample light can be maintained at a low level without any hindrance so that the photomultiplier tube can be effectively radiated and cooled without causing inconvenience such as increase in space. It is an issue.

[0006]

The present invention has the following structure in order to achieve the above object.

According to the first aspect of the present invention, the photodetector having a cathode cooling plate thermally connected to the cathode is used as the detector for receiving the light from the light emitting unit through the spectroscopic unit. In the emission spectroscopic analysis apparatus housed in the above, the emission spectroscopic analysis apparatus is configured by including connecting means for thermally connecting the cathode cooling plate to a part of the housing through a heat transfer means.

According to a second aspect of the present invention, in the emission spectroscopic spectroscopic device of the first aspect, the connecting means mechanically supports the photomultiplier tube from the housing.

According to a third aspect of the present invention, in the emission spectroscopic analysis apparatus according to the first aspect, temperature control is performed so that the spectroscope including the detection unit has a constant temperature.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
A description will be given with reference to FIG.

1 and 2 relate to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view of a detecting portion of an emission spectroscopic analyzer.
FIG. 3 is an enlarged vertical sectional view of a main part thereof.

In FIG. 1 and FIG. 2, reference numeral 10 indicates the whole of a detector for receiving the sample light from the light emitting portion through the spectroscopic portion, and 11 is a side-on in which the sample light is detected in the lateral direction. Type photomultiplier tube, 12 is its socket, 13
Is a copper housing.

As shown in FIG. 2, the photomultiplier tube 11 has an outer periphery hermetically sealed by a glass bulb 11b and a cathode cooling plate 11a on the top of the bulb 11b. Board 11a
Is exposed to the outside of the valve 11b and the valve 1
It is joined to the extended end of the cathode electrode 11c inside 1b.

On the other hand, on the inner surface of the top plate portion 13a of the housing 13,
A rubber cap 14 is attached. A Peltier effect element 15 is held inside the cap 14. In addition, the top of the bulb 11b of the photomultiplier tube 11 is fitted into the lower end opening of the cap 14, whereby the photomultiplier tube 11 and its socket 12 are held in a fixed posture in the cap 15. . The socket 12 does not need to be attached to the housing 13 in particular, and may be inserted into the photomultiplier tube 11 as illustrated.

Inside the cap 14, the cathode cooling plate 11 a of the photomultiplier tube 11 is arranged in the Peltier effect element 15.
It is thermally joined to a part of the housing 13 via. Specifically, the cathode cooling plate 11 a of the photomultiplier tube 11 is bonded to one surface of the Peltier effect element 15, and the other surface of the Peltier effect element 15 is bonded to the top plate portion 13 a of the housing 13.

In the above structure, the photomultiplier tube 11,
Particularly, the cathode electrode 11c which easily generates heat is forcibly cooled by the cooling action of the Peltier effect element 15 via the cathode cooling plate 11a, and moreover, the Peltier effect element 15
Since the heat possessed by itself is radiated to the outside through the housing 13, the photomultiplier tube 11 is strongly cooled,
The increase in dark current is suppressed, and the lower limit of light detection is maintained at a low level.

Further, in the structure of the conventional detecting section, as shown in FIG. 6, the photomultiplier tube 7 is held by the socket 9, so that depending on how the photomultiplier tube 7 is inserted into the socket 9, Although the attitude of the photomultiplier tube 7 may be misaligned, the valve of the photomultiplier tube 11 is directly held by the cap 14 in the configuration of the detection unit 10 of the present invention.
The attitude of the photomultiplier tube 11 is unlikely to change.

In the above embodiment, the cap 14
Is attached to the top plate portion 13a by fitting the annular convex portion 14a into the groove formed in the top plate portion 13a of the casing, but the cap 14 is attached to the casing 13 side with an adhesive. Alternatively, as shown in another embodiment of FIG. 3, a flange 14b is formed on the cap 14,
The flange 14b may be attached to the housing 13 side with the screw 16.

FIG. 4 is an enlarged vertical sectional view of a main part of a detecting section according to still another embodiment. In this embodiment, a metal plate 17 having a good thermal conductivity such as aluminum is embedded in the cap 14 so as to be in contact with one surface of the Peltier effect element 15. The metal plate 17 has a top plate. A resin screw 18 is screwed through the portion 13a. The reason why the screw 18 is made of resin is to prevent the heat of the housing 13 from returning to the metal plate 17 side. The metal plate 17 is made of an insulating material 1 having excellent thermal conductivity such as an epoxy resin insulating material.
Via the cathode cooling plate 11a of the photomultiplier tube 11
Is thermally bonded to.

In this embodiment, the photomultiplier tube 11 is strongly cooled, and its posture is maintained without being deformed, and the screw 18 and the metal plate 17 are screwed together so that the cap 1
4 is attached to the housing top plate portion 13a, and the Peltier effect element 15 and the top plate portion 13a are closely joined to each other, so that the heat radiation effect from the Peltier effect element 15 to the housing 13 becomes better.

In addition, in each of the above embodiments, the photomultiplier tube 11 and its socket 12 are held on the housing 13 side via the cap 14, but the socket 12
Can be attached to the case 13 side as before,
In that case, the bulb top of the photomultiplier tube 11 does not need to be fixed to the housing 13 side in particular, and the Peltier effect element 15 is sandwiched between the cathode cooling plate 11a of the photomultiplier tube 11 and the housing 13. Should be intervened in.

In the above embodiment, if the temperature adjusting means is further provided and the temperature adjusting means adjusts the temperature of the entire spectroscopic section (not shown) and the detecting section 10 to a constant temperature, the cathode electrode 11c. The cooling effect of (1) is enhanced, and the dark current can be further reduced, and the stability of measurement is increased accordingly.

[0023]

According to the first aspect of the present invention, since the cathode cooling plate of the photomultiplier tube is thermally joined to a part of the housing through the heat transfer means, cooling is strong. The dark current is suppressed to a low level,
It became possible to detect weak sample light.

According to a second aspect, the photomultiplier tube is mechanically supported on the housing side by the connecting means,
It is possible to obtain the effect that the attitude of the photomultiplier tube does not easily change.

Further, according to the third aspect, the temperature is adjusted so that the entire spectroscopic section and the detection section have a constant temperature.
The effect of cooling the cathode is enhanced, and the dark current can be further reduced, and the effect that the stability of measurement is increased accordingly is obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a detection unit of an emission spectroscopic analyzer according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of a main part of the above embodiment.

FIG. 3 is an enlarged vertical sectional view of a main part of a detection unit according to another embodiment of the present invention.

FIG. 4 is an enlarged vertical sectional view of a main part of a detection unit according to still another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of an emission spectroscopy analyzer.

FIG. 6 is a vertical cross-sectional view of a conventional detection unit of an emission spectroscopic analyzer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Detection part 11 ... Photomultiplier tube 11a ... Cathode cooling plate 13 ... Housing 14 ... Cap 15 ... Peltier effect element

Claims (3)

[Claims] 1. A detection unit for receiving light from a light emitting unit via a spectroscopic unit, a photomultiplier tube having a cathode cooling plate thermally connected to a cathode is housed in a thermally conductive metal housing. The emission spectroscopic analysis apparatus configured as described above, further comprising a connecting means for thermally connecting the cathode cooling plate to a part of the housing via a heat transfer means. 2. The optical emission spectroscopic analyzer according to claim 1, wherein the photomultiplier tube is mechanically supported from the housing by the connecting means. 3. The emission spectroscopic analyzer according to claim 1, wherein the spectroscope including the detector is temperature-controlled so that the spectroscope has a constant temperature.