JPS61239184A - Low-speed electron measuring device - Google Patents

Abstract

PURPOSE:To always detect a low-speed electron with prescribed sensitivity by varying an anode voltage in one direction in a state that the low-speed electron does not invade, and setting the anode voltage of the time when measuring the low-speed electron by using a voltage of the time point when a discharge state has been varied, as a parameter. CONSTITUTION:In the inside of a container-shaped cathode 1 in which an inflow port 1a of a low-speed electron has been formed in one end, an anode 2 and lattice electrodes 3, 4 for forming a non-uniform electric field are provided, and the anode 2 is connected to a voltage variable type high voltage generating device 5, and generates an electric field rough for generating the discharge, when the low-speed electron has flowed in. Also, a controlling circuit 10 varies an output voltage value from the device 5 in one direction in a state that no low speed electron flows in, detects a voltage of the time point when a discharge state of the anode 2 has been varied, and sets a voltage for generating the discharge of a prescribed level when the low-speed electron has been detected, to the device 5, based on this detected voltage. In this way, the low-speed electron can be detected with a prescribed sensitivity without using a special atmospheric state detecting means and an operating means.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a technique for correcting the discharge rate, that is, the reference point, of a device that measures slow electrons using gas discharge in the atmosphere.

(Conventional technology) Photoelectrons, thermoelectrons, and exoelectrons (
To detect low-velocity electrons (hereinafter referred to as slow electrons), a PA electrode is placed inside a cathode made of a conductive container that is open to the atmosphere through an opening.
First and second grids are disposed in the opening, and a voltage of about 3 or 4 KV is applied between the cathode and the anode, and the first and second grid electrodes are normally 100V and 80V, respectively.
A low speed electronic measurement device configured to apply a voltage on the order of V is used.

In this device, when low-speed electrons emitted from the sample surface pass through the space and enter the cathode through the opening, the low-speed electrons trigger a discharge at the anode, and a pulse signal is output from the anode. This pulse signal activates the counting means, while increasing the potential of the first grid electrode to prevent the development of discharge, and at the same time lowering the second grid electrode to a negative potential to neutralize the positive ions generated during the discharge. The number of low-speed electrons generated is measured while repeating the process of returning to the original state.

By the way, this low-speed electron detection device communicates with the atmosphere through an opening, so as shown by the solid lines in Fig. Variations in the conditions are directly measured, and as a result, the discharge conditions vary and the counting rate for the same anode voltage changes significantly, resulting in a large measurement error in the measurement results.

Of course, such problems can be solved by detecting atmospheric conditions using a barometric pressure sensor, temperature sensor, humidity sensor, etc., and adjusting the anode voltage based on the detection results, but this requires various sensors. In addition, the control amount must be determined by taking into consideration the differences in the degree of influence of each parameter that governs the atmospheric conditions on the discharge conditions and their interrelationships, which is a new problem that requires special calculation means. cause problems.

(Objective) In view of these problems, the present invention provides a reference point correction means that can detect low-velocity electrons with constant sensitivity regardless of changes in atmospheric conditions without using an atmospheric condition detection sensor or special calculation means. The purpose of the present invention is to provide a low-speed electronic measurement device equipped with the following.

(Structure) Therefore, details of the present invention will be described below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which reference numeral l denotes a container-shaped cathode that is open to the atmosphere through an opening 1a formed at the bottom, and the internal space is unequal. An anode 2 for forming an electric field, and a first grid electrode 3 for controlling the discharge. The second pole electrode 4 is arranged so as to be spaced between the upper and lower parts. The anode 2 is connected to a variable voltage high voltage generator 5 to generate an electric field sufficient to cause a discharge when low-speed electrons flow in, and is connected to an amplifier 7 via a DC blocking capacitor 6. It is connected.

The first grid electrode 3 is connected to the first pulse generator 8.
At normal times, the voltage is about toov, and the voltage is amplified.
Te for a certain period of time due to the output of the pulse signal from the device 7.
1m・, *ts"°°"1°'"0"'"'th
``5tt6.1=The M child electrode 4 is connected to the second pulse generator 9, and the voltage is normally about 80V, and the output of the pulse signal from the amplifier 7 continues the negative 1.. 30V for a certain period of time Te. 10 is a control diagram constituting a characteristic part of the present invention. In the state where the inflow of low-speed electrons is blocked, that is, in the large atmosphere state detection mode, , variable voltage high voltage □ □, changing the output voltage of the generator 5 in one direction,
When the output from the counter 11 reaches a preset counting rate, voltage scanning is stopped and the anode voltage at this time is taken in as a control parameter, and in measurement mode, the voltage at the time when scanning is stopped is taken in as a parameter. −・Variable high voltage generator that generates a constant level of discharge
It is configured to output from a5. Note that the reference numeral 12 in the figure indicates a display device that processes the signal from the counter 11, converts it into a counting rate, etc., and displays the converted signal.

Next, we will explain the operation of the device configured in this way in a second way.
The explanation will be based on the waveform diagram shown in the figure.

It is assumed that the current atmospheric conditions are as shown in Fig. 5 (a), (b), and ■.

When the apparatus is operated with the sample S placed below the cathode opening 1a, the low-speed electrons emitted from the surface of the sample S are transferred to the anode 2.
When the electrons reach the vicinity of the anode 2 in this way, they pass through the second grid electrode 4 and the first grid electrode 3 sequentially and are attracted to the anode 2 in response to the electric field formed by the electrons.
These electrons are rapidly accelerated by the strong electric field distributed near the anode, ionizing the surrounding atmosphere and causing a discharge.As a result, the anode 2 causes a rapid potential drop. cause. This potential drop becomes a pulse signal via the DC blocking capacitor 6, is amplified by the amplifier 7, and is sent to the counter 1.
1 and displayed on the display device 12 as the frequency and number of low-speed electrons.

On the other hand, this pulse signal is transmitted to the first and second pulse generators 8
．． 9 and the voltage from the first pulse generator 8 is e.g.
The electric potential of the first grid electrode 3 is raised to 400 V by superimposing a pulse with a time width Te of 00 V and extinguishing the discharge. In addition, a pulse is output from the second pulse generator 9,
When the potential of the second grid electrode 4 is lowered to -30 V with respect to the cathode 1 and the cations generated in the cathode 1 due to the discharge are extinguished, the second and second pulse generators 8.9 The pulse output from the detector stops, and the measuring device returns to its initial state and waits for the next influx of low-speed electrons.

In such a state, atmospheric conditions such as atmospheric pressure, temperature, and humidity change, causing fluctuations in conditions related to discharge such as electron mobility near the anode, and the discharge conditions change as shown in Figure 5 (a) (
Assume that the state shown in (ii) of b), that is, the counting rate for the same anode voltage has decreased.

Therefore, first, a state is set in which electrons cannot enter through the cathode opening 1a, for example, the second grid electrode 4 is set to a negative potential.

When the control circuit 10 is set to the atmospheric condition detection mode after completing such preparations, the control circuit 10 operates the variable voltage high voltage generator 5 to generate high voltage in one direction, for example, from the low voltage side. Start voltage scanning towards the side. At the beginning of voltage scanning, a voltage sufficient to cause a gas discharge is not applied to the anode 2, so a non-discharge state is maintained. When the voltage is increased in this state, as soon as a voltage sufficient to start discharge begins to be applied to the anode 2, it enters the self-sustaining discharge region (the curve shown by the dotted line in Figure 5), and the amplifier 7 A pulse signal corresponding to the number of gas discharges is output. The counter 11 counts this pulse signal and outputs the counted contents to the control circuit 10. The control circuit 10 includes a counter 11
At the point in time when the counting rate from 1 to 2 matches the set value, the voltage scanning of the variable voltage high voltage generator 5 is stopped, and at the same time, the output voltage Vd of the variable voltage high voltage generator 5 is detected. Needless to say, this voltage Vd indicates the atmospheric conditions that are governed by the mutual relationships between current atmospheric pressure, temperature, humidity, etc., that is, the discharge conditions indicated by ■ in Figure 5 (a) and (b). It is.

The control circuit 10 adjusts the output voltage of the variable voltage high voltage generator 5 by using the output voltage Vd at the time of discharge change as a parameter.
The discharge conditions are adjusted by shifting V to the high voltage side. As a result, the discharge conditions are returned to the conditions before the change in atmospheric conditions, that is, the same conditions as in FIG. 5 II, and thereafter, slow electrons are detected without any change in the counting rate for one slow electron.

FIG. 3 shows a second embodiment of the present invention, in which reference numeral 3 is an anode disposed inside a container-shaped cathode 1, and a conductive wire is formed into a loop shape, which will be described later. The anode temperature control circuit 15 receives electric power from the anode temperature control circuit 15 to raise the temperature by Joule heat. The anode 13 is connected to a variable voltage high voltage generator 14 to generate an electric field sufficient to cause a discharge when low-speed electrons flow in, and is connected to an amplifier 7 via a DC blocking capacitor 6. It is connected. Reference numeral 15 denotes an anode temperature control circuit which is a characteristic part of the present invention, and uses the voltage at the time when a preset counting rate is reached in the atmospheric condition detection mode as a parameter to maintain a temperature sufficient to cause a certain level of discharge. The heating power supply is configured to provide heating power.

Next, the operation of the apparatus configured as described above will be explained based on the waveform diagram shown in FIG.

Atmospheric conditions such as atmospheric pressure, temperature, and humidity change, causing fluctuations in conditions related to discharge such as electron mobility near the anode 13, and the discharge conditions are shown by II in Figure 5 (a) and (b). Assume that the state changes to the state shown in (■) in the same figure, that is, the state in which the counting rate decreases.

Therefore, first, a state is set in which electrons cannot enter through the cathode opening 1a, for example, the second grid electrode 4 is set to a negative potential.

After completing such preparations, the anode temperature control circuit 15
When set to the atmospheric condition detection mode, voltage scanning of the output voltage of the variable voltage high voltage generator 14 is started from the low voltage side to the high voltage side. When the anode voltage is increased in this state, the anode 13 enters the self-sustaining discharge region as soon as a voltage sufficient to start discharge begins to be applied, and the amplifier 7 generates a pulse signal corresponding to the number of gas discharges. Output. The counter 11 counts this pulse signal and outputs the counted contents to the anode temperature control circuit 15. The anode temperature control circuit 15 stops the voltage scanning of the variable voltage high voltage generator 14 when the counting rate from the counter 11 matches the set value, and
Its output voltage Vd' is detected. At the same time, the heating power to the anode is increased using the output voltage Vd' at the time of discharge change as a parameter, and the temperature of the anode 13 is shifted to the high temperature side by ΔT. This increases the temperature of the gas near the anode 13 and increases the mobility of electrons. As a result of this, the discharge conditions are returned to the conditions before the atmospheric state change, that is, the conditions indicated by II in Figure 5 (a) and (b), and from then on, the counting rate for one slow electron, that is, the detection sensitivity, Detects slow electrons without causing any change. Note: 1. If the ambient temperature rises or falls too much, the heating power to the anode is returned to its initial state before detecting the atmospheric condition. By doing so, the measurement error can be made as small as possible.

In the above-mentioned embodiment, voltage scanning is performed from the low voltage side, but scanning is performed from the high voltage side and the voltage variable type high voltage It is clear that the same effect can be obtained by controlling the output voltage of the voltage generator W15 or by controlling the heating power from the anode temperature control circuit 15.

In addition, in the embodiment described above, the discharge state is detected in the atmospheric state detection mode by changing the counting rate, but it is also based on the peak value of the pulse signal output from the amplifier 7 and the magnitude of the anode load current. Needless to say, it can be detected by

Further, in the above-described embodiments, a current is passed through the anode to directly heat the anode, but a heater may be disposed near the anode to heat the anode indirectly, with the same effect.

Further, in the embodiments described above, the measurement mode and the atmospheric condition detection mode are manually selected, but by using a timer or the like, each mode can be automatically switched alternately at a fixed period.

- (Effects) As explained above, according to the present invention, the anode voltage is changed in one direction in a state where slow electrons do not enter, and the voltage at the time when the discharge state changes is used as a parameter to determine the anode voltage when measuring slow electrons. Alternatively, since the anode temperature is set, low-speed electrons can always be detected with constant sensitivity without using special atmospheric condition detection means or calculation means.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a device showing one embodiment of Tama Kanmei;
3 is a waveform diagram showing the operation of the device shown in the above, FIG. 3 is a configuration diagram of the device showing another embodiment of the present invention, and FIG. 4 is a waveform diagram showing the operation of the device shown in FIG. FIGS. 5(a) and 5(b) are characteristic diagrams showing the relationship between the atmospheric condition and the counting rate in the low-speed electronic measuring device, respectively. ! ...Cathode 2,13...Anode 3.4...
Grid electrode applicant Riken Keiki Co., Ltd. (+5yis) Agent Patent attorney Keiji Nishikawa Katsuhiko Kimura Figure 1 Figure 3 Figure 4 Figure 5 (a) (b) Tsuyoshi Igo (7cV). Procedural amendment (written) August 30, 1985. Mr. Michibu Uga, Commissioner of the Patent Office. 1. Indication of the case 1985 Patent Application No. 80891 2. Name of the invention Low-speed electronic measuring device 3. Person making the amendment Relationship to the case Patent applicant 2-1 Hirosawa, Wako City, Saitama Prefecture Representative of RIKEN Miya Ryuko Shima 4, Agent 〒112 Telephone 03
(815) flloO 2-1-2 Koishikawa, Bunkyo-ku, Tokyo
No. 5, Detailed explanation of the invention column 6 of the specification subject to amendment, between line 9 and line 10 of page 13 of the specification of contents of the amendment
. Add the following text.

Claims (2)

[Claims] (1) A container-shaped cathode with an inlet for slow electrons formed at one end, an anode disposed inside the cathode, and a variable voltage that outputs at least enough voltage to cause discharge to the anode. type high voltage generating means, and detecting the voltage at the time when the discharge state of the anode changes by changing the output voltage value from the high voltage generating means in one direction in a state where there is no inflow of slow electrons, and detecting the detected voltage. a control means for setting the high voltage generating means to a voltage that causes a certain level of discharge when low speed electrons are detected, based on the above. (2) A container-shaped cathode with an inlet for slow electrons formed at one end, an anode disposed inside the cathode, and a variable voltage that outputs at least enough voltage to cause discharge to the anode. type high voltage generating means, and detecting the voltage at the time when the discharge state of the anode changes by changing the output voltage value from the high voltage generating means in one direction in a state where there is no inflow of slow electrons, and detecting the detected voltage. and an anode temperature control means for heating the anode to a temperature that causes a constant level of discharge during low-speed electron detection based on the following.