JP3573071B2 - Discharge lamp for magnetometer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an external electrode type discharge lamp. In particular, the present invention relates to an external electrode type helium lamp used as a light source of a magnetometer or an external electrode type discharge lamp filled with an alkali metal.
[0002]
[Prior art]
U.S. Pat. Nos. 3,206,671 and 3,350,632 disclose a helium-filled discharge lamp and a magnetometer operated by a helium-filled gas cell. This magnetometer turns on a helium lamp with a high frequency of several tens to several hundreds of MHz, circularly polarizes the light of the lamp and transmits the inside of a helium gas cell, and the helium spectral line is separated in conjunction with a change in a magnetic field. A system that utilizes the sensing of a change in the helium spectrum caused by the so-called Zeeman effect has been used.
[0003]
Inside this system, the helium lamp is used in a completely sealed, darkened container that does not allow outside light to enter, and the environment in which the magnetometer is operated can be used in a cold region at -50 ° C. is there.
Under this condition, the number of initial electrons inside the lamp, which triggers the discharge, is extremely reduced, so that the lamp is difficult to start, causing a significant delay in starting and causing a problem that the discharge does not start.
[0004]
In order to avoid the lamp from turning on and off in the dark, not only helium but also a small amount of tritium, which is a radioactive substance, is sealed inside the lamp. Tritium is an isotope of hydrogen, which does not emit light during lamp operation and does not affect discharge, but emits beta rays when one neutron inside the nucleus becomes helium instead of proton. Accordingly, electrons necessary for starting can be generated by beta rays inside the lamp without affecting other characteristics of the helium lamp, and the starting performance can be greatly improved.
[0005]
[Problems to be solved by the invention]
However, since tritium is a radioactive substance that is gaseous at room temperature, it is very difficult to manage tritium, which complicates the installation of the lamp. And safety measures are troublesome. In Japan, the handling is very strictly regulated. Therefore, considering the cost of the lamp, it is virtually impossible to manufacture a lamp in which tritium is sealed in Japan.
[0006]
Japanese Patent Laid-Open No. Hei 10-188910 discloses, for example, a conventional technique for solving a start delay in a state where external light cannot be expected (under darkness). In order to improve the dark start characteristics of an external electrode type fluorescent lamp in which a fluorescent substance is coated on the inner surface of a glass tube, this technology uses a conductive material and a glass tube inner surface region corresponding to a region where a low-voltage side electrode is disposed. Attached over the glass tube inner surface area corresponding to the area where none of the electrodes are arranged, and using a high frequency, high voltage pulse of the power supply, a part of the conductive substance on the glass tube inner surface corresponding to the low voltage side electrode. The electric field concentration as the negative electrode occurs, and electrons are easily emitted from the surface of the conductive material, and the dark startability is greatly improved as compared with the case where the conductive material is not provided.
[0007]
The present invention is limited to an external electrode type fluorescent lamp in which a fluorescent substance is coated on the inner surface of a glass tube, and the conductive substance is spread inside the glass tube so as to extend over the pair of external electrodes in the lamp axis direction. It is stated that the coating may be performed in the radial direction and may be mounted at any position in the longitudinal direction of the lamp.
[0008]
However, in a discharge lamp for a magnetometer in which helium or an alkali metal is sealed, light is emitted from the lamp in two regions between the central high-voltage electrode and the low-voltage electrodes at both ends of the central electrode. Since the lamp is different from a single aperture along the tube axis, the method of mounting the conductive material, the mounting position, and the characteristics of the conductive material are different from the conventional external electrode type fluorescent lamps. Technology is required.
[0009]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a discharge lamp for a magnetometer in which helium or an alkali metal is sealed, in which dark startability is improved without enclosing tritium.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a discharge container formed of a metal plate on the outer surface of a substantially cylindrical glass discharge vessel in which helium or an alkali metal is sealed, the discharge vessel being spaced from the center of the discharge vessel and near both ends thereof. By disposing three external electrodes consisting of one central high-voltage electrode and two end low-voltage electrodes in the container circumferential direction, and applying a high-frequency voltage between the central high-voltage electrode and the end low-voltage electrode, A discharge lamp for a magnetometer that emits light to the outside of the discharge vessel from two light-emitting regions sandwiched between the discharge vessel and a non-magnetic conductive substance corresponding to the central high-voltage electrode disposing portion. Over the inner surface portion and the inner surface portion of the discharge vessel corresponding to the non-arranged portion where the three external electrodes are not arranged, the two are arranged symmetrically in the lamp axis direction in the two light emitting regions in the two light emitting regions. Is provided so that One conductive material is to a magnetometer for a discharge lamp, characterized in that it is provided in the discharge vessel inner surface opposite to the feeding portion of the external electrode. Preferably, the conductive material has a linear shape.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing an embodiment of the lamp of the present invention. FIG. 1A is an overall view of a lamp 10 of the present invention, and FIG. 1B is a cross-sectional view taken along the line AA ′ in FIG. 1A.
On the outer surface of the cylindrical discharge vessel 1, a central high-voltage electrode 2 and end low-voltage electrodes 3, 3 'are arranged at intervals in the circumferential direction of the discharge vessel 1. A high voltage having a frequency of 50 kHz and a peak voltage of 1000 V is applied, and a high frequency voltage of 50 MHz is applied after the start. Helium gas or the like is sealed inside the glass tube 1, and a conductive substance 4 is also arranged on the inner surface of the discharge vessel 1.
[0012]
The conductive substance 4 exists inside the discharge vessel 1, but is shown by a solid line in FIG. 1 for convenience. The reason that the startability of the lamp of the present invention can be improved by the presence of the conductive substance 4 on the inner surface of the discharge vessel 1 is that when a voltage is applied to the central high- To the conductive material 4 through the discharge vessel 1, and further a creeping discharge leading to the end low-voltage electrode 3 or 3 ′ occurs through the discharge vessel 1, generating electrons that become initial electrons inside the lamp. It is considered that the main discharge of the lamp starts without delay of starting.
[0013]
FIG. 2 is a layout diagram when the lamp 10 of the present invention is used. As shown in FIG. 1 (a), the lamp 10 is connected between a central high-voltage electrode 2 connected to a high-frequency power supply (RF in FIG. 2) and two end low-voltage electrodes 3, 3 'grounded. It has two light emitting areas S1 and S2. This is because when a high-accuracy magnetometer capable of three-dimensional exploration is manufactured, the helium gas cells 6 and 6 'are arranged so as to correspond to the X, Y, and Z axis directions, respectively. Since two sets of gas cells for each axis are used to increase the accuracy, the lamp 10 has two light emitting areas. The two gas cells 6, 6 'arranged with respect to this one axis pass through the interference filters 11, 11' and the circularly polarizing elements 12, 12 ', respectively, and transmit the circularly polarized light in opposite directions. By taking the logical product of the magneto-optical resonance signals as the output signal voltage converted by the photodetectors 7, 7 ', the accuracy of the magnetometer is improved.
[0014]
Therefore, it is preferable that the emission spectrum and emission intensity of helium or alkali metal in the two emission regions of the lamp are the same. If the light emission intensities of the two light emitting regions are different, a difference also occurs in the magnetic sensitivity of the gas cell. In this case, it is impossible to adjust the intensity of the light emitting area of the lamp by the power supply, so that the magnetic sensitivity of the two gas cells needs to be calibrated by the input power of the gas cells. In this case, the sensitivity of the magnetometer is reduced because calibration is performed on the gas cell on the light emitting region side with low sensitivity.
[0015]
FIG. 2 shows the positional relationship between the gas cells 6, 6 'arranged in the X direction and the lamp 10 of the present invention.
FIG. 3 shows the positional relationship between the gas cells 6, 6 arranged in the Y and Z directions and the lamp 20 of the present invention.
The lamp 10 of FIG. 2 and the lamp 20 of FIG. 3 are arranged at 90 degrees on a plane parallel to each other.
Between the gas cells 6, 6 'and the lamps 10, 20, lenses 5, 5' interference filters 11, 11 'circularly polarizing elements 12, 12' for taking light from the lamps 10, 20 into the gas cells 6, 6 'are arranged. The light transmitted through the gas cells 6, 6 'is irradiated on the photodetectors 7, 7' and converted into voltage signals.
[0016]
The conductive substance 4 of the present invention is applied to the inner surface of the discharge vessel 1 corresponding to the portion where the central high-voltage electrode 2 is disposed and to the inner surface of one of the two light emitting regions S1 and S2. It has a sufficient effect on dark startability. However, the light emitting regions S1 and S2 on which the conductive material 4 is applied have a 5 to 10% decrease in light emission intensity. Therefore, when the conductive material 4 is applied only on one light emitting region, the two light emitting regions S1 , S2, a difference occurs in the light emission intensity. Therefore, the conductive material 4 must be mounted in the same shape in the two light emitting regions S1 and S2 and symmetrically in the lamp axis direction about the central high voltage electrode 2.
[0017]
Further, in the present invention, it is necessary to consider the mounting position of the conductive substance 4 also in the lamp radial direction. FIG. 1B is a sectional view taken along line AA ′ in FIG. The portion where the conductive material 4 is disposed in FIG. 5A must be disposed 180 ° opposite to the power supply portion 8 of the external electrode and the center of the lamp having a circular cross section. This is for setting the conductive substance 4 so as not to block the light with respect to the gas cell 6 when transmitting the light from the lamp to the gas cell 6 as shown in FIG. In the lamp axis direction.
[0018]
Further, the material of the conductive substance in the present invention is limited. The lamps 10, 20 are located very close to the gas cells 6, 6 '. Since an alternating magnetic field is applied to the gas cells 6 and 6 ′ to cause the splitting of the spectral lines due to the Zeeman effect in the helium spectrum emitted inside the gas cells, when the conductive material 4 is a magnetic material such as nickel, The conductive material 4 is magnetized and affects the discharge of the lamps 10 and 20.
[0019]
For this reason, it became impossible to detect the change of the magnetic field which should be sensed originally, and it turned out that it cannot operate as a magnetometer. The conductive material 4 used in the present invention is a conductive paint such as a silver paste or a carbon paste, which is nonmagnetic, has good applicability, and is easy to use. Further, even if a commercially available copper tape or aluminum tape having a width of about 1 mm was adhered to the inside of the lamp as a conductive substance, it could be used sufficiently.
[0020]
【Example】
A specific example of the external electrode type discharge lamp according to the present invention shown in FIG. 1 will be described in detail.
The discharge vessel 1 is made of glass and has an overall shape of a tube. The inside of the discharge vessel 1 is evacuated to a predetermined vacuum, then filled with helium gas, both ends are closed, and the inside is sealed. The discharge vessel 1 is made of an aluminosilicate glass that transmits little helium, and has a length of 80 mm and an outer diameter of 6.4 mm. The electrodes 3, 3 'are pipe-shaped and provided on the outer surface of the glass tube 1 along the axial direction. This electrode is made by, for example, sheet metal working a copper plate having a thickness of 0.3 mm, and is fixed to the discharge vessel with a silicon adhesive.
[0021]
The conductive material 4 is, for example, a silver paste having a size of about 1 mm in width × about 54 mm in length, and is arranged on the inner surface of the discharge vessel 1. In the figure, the discharge vessel 1 is arranged linearly below the inner surface. By arranging them linearly, a wide light emitting area of the discharge vessel can be secured. The material of the conductive substance 4 is a silver paste.
[0022]
Here, the conductive material 4 is located on the inner surface of the discharge vessel 1, the inner surface area of the discharge vessel 1 corresponding to the area where the central high-voltage electrode 2 is provided, and the area where no electrodes are provided. And over the discharge vessel 1 corresponding to the inner surface area. In addition, the conductive substance 4 may be arranged on the inner surface of the discharge vessel 1 corresponding to the area where the other end low-voltage electrodes 3 and 3 'grounded are provided.
[0023]
Next, an experiment showing the starting characteristics of the external electrode type discharge lamp in which helium is sealed in the discharge vessel 1 will be described. FIG. 4 shows the experimental results, in which the horizontal axis represents the time from when a voltage is applied between the central high-voltage electrode 2 and the end low-voltage electrodes 3, 3 until the lamp is turned on, and the vertical axis is the horizontal axis. It represents the starting probability for the indicated time.
[0024]
As a comparative example with the product of the present invention, a lamp without conductive material 4 and a lamp with tritium sealed without conductive material were lit one by one at an interval of 10 seconds in an environment without external light. Was turned on 100 times at each time, and how many seconds each was started was measured.
[0025]
In FIG. 4, the horizontal axis represents the time until starting, and the vertical axis represents the starting probability. For example, it can be read from the line derived from the plot that “the lamp starts with a certain probability by a certain starting time”. It is determined that the startability is better as the vehicle starts 100% by the time. The lamps of the present invention, indicated by line (A), are all starting within 5 ms. However, in the lamp shown in line (B), which does not include the conductive substance 4, only about 0 to 5% of the lamp is turned on in 5 ms, and 70% of the lamp is turned on in 100 ms.
[0026]
Also, in the lamp filled with tritium shown by the line (C), only 0 to 15% of the lamp is turned on in 5 ms, and 70% is turned on in 40 ms. Thus, it is clear how the lamp of the present invention is excellent in startability.
The gas sealed in the discharge vessel 1 may be an alkali metal vapor such as potassium, sodium, cesium, etc. other than helium.
[0027]
【The invention's effect】
As described above, since the discharge lamp for a magnetometer of the present invention can always have good starting characteristics, it is used when mounted on a magnetometer and left for a long time in a dark state where external light cannot be expected. However, the lamp can be started and lit with no problem and with a simple structure without sealing tritium.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a lamp of the present invention.
FIG. 2 is a diagram showing an arrangement when the lamp of the present invention is used.
FIG. 3 is a view showing an arrangement when the lamp of the present invention is used.
FIG. 4 is a diagram showing a measurement result of a starting characteristic.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 discharge vessel 2 central high-voltage electrode 3, 3 ′ end low-voltage electrode 4 conductive material 5, 5 ′ lens 6, 6 ′ gas cell 7, 7 ′ photodetector 8 power supply section 9, 9 ′ power supply section 10 lamps 11, 11 'Interference filter 12, 12' Circular polarizing element 20 lamp

Claims (2)

On the outer surface of a substantially cylindrical glass discharge vessel filled with helium or an alkali metal, a metal plate is used, and a central high-voltage electrode and a central high-voltage electrode are arranged in the circumferential direction of the discharge vessel at intervals around the center and near both ends of the discharge vessel. By providing three external electrodes consisting of two end low-voltage electrodes, by applying a high-frequency voltage between the central high-voltage electrode and the end low-voltage electrode, from two light-emitting regions sandwiched between each external electrode, A discharge lamp for a magnetometer that emits light to the outside of the discharge vessel, wherein a non-magnetic conductive substance is provided on the inner surface portion of the discharge vessel corresponding to the central high-voltage electrode disposition portion, and In the two light-emitting regions, the two light-emitting regions are arranged so as to be symmetrically arranged in the left-right symmetrical manner over the discharge vessel inner surface portion corresponding to the non-arranged portion and the conductive member. The substance is the feeder of the external electrode Magnetometers discharge lamp, characterized in that it is provided in the discharge vessel inner surface of the opposite side. The discharge lamp for a magnetometer according to claim 1, wherein the conductive material has a linear shape.

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