JPS63269440A - Sampling streak device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the time resolution by arranging a magnetic field generating coil on a sampling streak tube aud feeding the preset current to the coil. CONSTITUTION:A magnetic field generating coil 21 is arranged on a sampling streak tube, and the preset current is fed to the coil 21 to generate the magnetic field. A linear photoelectron beam is thus rotated, the linear photoelectron beam is made parallel with the direction of a deflecting electrode 6, and a streak image is made vertical to the time axis. The problem occurring from the drift of the parallelism in assembling an accelerating slit electrode 10 and an output slit electrode 7 can be simply removed by adding the magnetic field generating coil 21. The deterioration of the time resolution is thereby prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sampling streak device used in a waveform measuring device for high-speed repetitive pulsed light.

[Conventional technology]

Conventionally, a sampling streak device has been used as a waveform measuring device for high-speed repetitive pulsed light.

Figure 5 is a diagram showing the configuration of such a conventional sampling streak tube. Figure (a) is a view of the streak tube seen from the photocathode side, and figure (b) is a view of the streak tube including its tube axis and deflection. FIG. 6, a cross-sectional view taken along a plane perpendicular to the electrodes, is a diagram showing the deflection voltage waveform.

In the figure, 1 is a cylindrical vacuum vessel, 2 is a photocathode, 3 is a mesh electrode, 4 is a focusing electrode, 5 is an anode plate, 6 is a deflection electrode, 7 is an output slit electrode, 8 is a fluorescent surface, and 9 is a high speed It is a repetitive pulsed light.

First, the operation of this device will be explained. High-speed repetitive pulsed light 9 is linearly imaged onto the photocathode 2 by an incident optical system. At this time, the optical system is adjusted so that the line direction of this linear optical image is parallel to the output slit electrode when viewed from the photocathode 2 side. When a linear photoelectron beam corresponding to this linear shape is emitted from the photocathode 2, it is accelerated by the mesoche electrode 3, and is transferred to the output slit electrode 7 by an electron lens formed by a focusing electrode 4 and an anode plate 5 having an aperture in the center.
is again imaged as a linear electron image on the surface of the This linear photoelectron image is further swept on the output slit electrode 7 in a direction perpendicular to the slit by applying a sawtooth wave voltage as shown in FIG. 6 to the deflection electrode 6. Since the longitudinal directions of the slits of the deflection electrode 6 and the output slit electrode 7 are arranged in parallel, when the linear photoelectron image is swept, at a certain timing, a group of electrons forming the linear photoelectron image crosses the slit. , and will be cut again by the slit electrode 7 at the next timing. That is, only photoelectrons corresponding to a certain time of the incident pulsed light pass through the slit and collide with the fluorescent surface 8, causing light emission. Therefore, if the timing of the sweep is shifted while repeating the sweep in synchronization with the incident light, light emission corresponding to the light intensity of the incident light pulse will sequentially occur on the fluorescent surface 8, and this will be transmitted to the photomultiplier tube. Data on the intensity change waveform of the optical pulse can be obtained by extracting it as an electrical signal.

On the other hand, most of the thermoelectrons emitted from the photocathode and photoelectrons emitted by repeated reflection within the input window and reflection from the electrode are removed by a slit accelerating electrode instead of the mesh electrode 3 described above, and the signal photoelectron beam is It is known that by passing through the acceleration slit electrode, the bank ground on the output surface can be reduced and the S/N ratio can be improved.

Figure 7 is a diagram showing a conventional sampling streak tube using an accelerating slit electrode, where (a) is a cross-sectional view taken along a plane that includes the tube axis and is perpendicular to the deflection electrode, and (b) is a sectional view of the slit electrode. It is a diagram showing the above linear photoelectron image, and the same numbers as in FIG. 5 indicate the same contents.

In the figure, 10 is an accelerating slit electrode, 11 is a linear photoelectron beam, 12 is a photoelectron due to thermoelectrons or stray light, and 13 is a linear photoelectron image formed on the slit electrode.

In FIG. 7(a), photoelectrons 12 due to thermoelectrons and stray light emitted from the photocathode 2 are captured by the slit electrode 10, and only the linear photoelectron beam 11 passes through the slit and is imaged on the output lift electrode 7. However, as described above, an optical image sampled from the fluorescent surface 8 is detected.

(Problems to be Solved by the Invention) By the way, the slit of the acceleration slit electrode 10 in FIG. If the slit width is made smaller in order to increase the If the parallelism is poor, the linear photoelectron image formed on the slit electrode 7 will be tilted and deviated from parallel to the slit, as shown in Figure 7 (b), and this will change over time. This results in a decrease in resolution.The reality is that the parallelism of these electrodes is unavoidably tilted to some extent due to assembly accuracy.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a sampling streak device that solves the problem caused by the misalignment of parallelism between the acceleration slit electrode and the output slit electrode.

[Means for solving problems]

To this end, the sampling streak device of the present invention is characterized in that a magnetic field generating coil is disposed in the sampling streak tube, and a linear photoelectron beam is rotated in a plane perpendicular to the tube axis by passing a predetermined current through the coil. .

[Effect]

The sampling streak device of the present invention arranges a magnetic field generating coil in a sampling streak tube, and generates a magnetic field by passing a predetermined current through the coil, thereby causing rotation in a linear photoelectron beam, thereby separating the linear photoelectron beam and the deflection electrode. The streak image is made perpendicular to the time axis.

〔Example〕

Examples will be described below with reference to the drawings.

Figure 1 shows an embodiment of the sampling streak device of the present invention, in which (a) is a view of the photoelectric device, and (b) is a view taken along a plane that includes the tube axis and is perpendicular to the deflection electrode. It is a sectional view, and the same numbers as in FIG. 7 indicate the same contents. In the figure, 21 is a magnetic field generating coil, 22 is a coil power supply, 23, 24 is a DC power supply, and 25 is a variable resistor.

In the figure, the slit width of the slit acceleration electrode 10 is 60 mm.
The length is 3N. The slit width of the output lift electrode is 100 μm and the length is 6 fi. -5KV from the reference potential point (ground voltage) to the photocathode 2 of the streak tube;
-4KV for the slit accelerating electrode 3, about -4KV for the focusing bridge
, 4 KV, and a ground potential is applied to the anode plate 5, output slit electrode 3, and fluorescent surface 8, respectively. One side of the deflection electrode 6 is grounded, and a repetitive sawtooth voltage is applied to the other side. Furthermore, a magnetic field generating coil 21 having a center axis coinciding with the tube axis is arranged between the photocathode 2 and the anode. The inner diameter of the coil is 60 m, the outer diameter is 65 m, and the length is 25 m, about 200 m.
It is turn-wound, and the coil is Dc'rtl? A power supply 22 that supplies JL is connected.

Here, an experimental tube was made in which this electrode was replaced with a fluorescent surface at the position of the output lift electrode 7 of the sampling streak tube, and the results of the experiment will be explained.

In this case, OV is applied to both sides of the deflection electrode, i.e.
Viewed from the photocathode side of the experimental tube operated as an image tube without streak operation, a linear optical image is incident on the center of the slit accelerating electrode parallel to the longitudinal direction of the slit, and a linear optical image is projected onto the output surface of the experimental tube. form a static light image. When current is applied to the coil in this state, it is possible to rotate the linear optical image on the output surface, and furthermore, this rotation is caused by the generated magnetic field, which causes the linear photoelectron beam to move toward the tube axis between the accelerating slit electrode 10 and the anode plate 5. It was also found that this occurs due to rotation within a vertical plane.

As shown in FIG. 2, the magnetic flux 26 generated by the magnetic field generating coil 21 has a distribution as shown in FIG. As shown in (b), forces acting in opposite directions as shown by the arrows in the figure act on the electron beams that pass through points A and B, which are symmetrical with respect to the center 0 of the tube, and this force goes to the periphery. This is thought to be due to the fact that it becomes larger over time.

FIG. 3 shows the relationship between coil supply current and rotation angle.

As can be seen from the figure, linearity is maintained within a coil supply current of ±300 mA and a rotation angle of approximately ±10”, and the lines of the linear optical image do not become distorted or blurred even when rotation is generated by a magnetic field. Therefore, by utilizing this fact, even if the acceleration slit electrode is not parallel to the output slit, it can be made parallel to the output slit by rotating the linear photoelectron beam.

Although the output image cannot be seen in the sampling streak device shown in FIG. 1, it can actually be adjusted using the following method. That is, a photomultiplier tube is placed after the output plane, the output current is passed through a load resistor to generate a voltage, and this voltage is observed with an oscilloscope.
A linear beam of light is imaged on the photocathode using DC light such as, and positioned approximately at the center of the accelerating slit electrode when viewed from the photocathode side. To the sampling streak tube, except for the deflection electrode, the voltage mentioned above when actually performing the sampling streak operation is applied, and one side of the deflection electrode is Ov, and the other side is Ov, for example, 60 Hz,
Apply 50V alternating current. In this way, the photoelectron beam is continuously incident on the output slit electrode, and a linear photoelectron image is swept over the output slit electrode surface. Therefore, each time this image passes through the output slit electrode, light emission is generated on the fluorescent surface, which is detected by the photoelectron beam, and the pulse interval is 1/6.
A pulse of 0 sec is obtained on the oscilloscope as shown in FIG. 4, and the coil current should be adjusted so that the pulse width (in hand) t is minimized. That is, the more the linear photoelectron image on the output slit electrode is inclined to the direction of the slit, the larger the pulse width t becomes. Good temporal resolution can be obtained by actually repeatedly applying a sawtooth wave voltage to one side of the deflection electrode in this adjusted state and measuring high-speed repetitive pulsed light.

In addition, the shape of the coil and streak tube in the above explanation,
If the operating conditions are changed, the relationship between the coil current and the rotation angle and the range in which distortion or blurring does not occur in the output linear image will also change, but the woody effect will remain the same.

〔Effect of the invention〕

As described above, according to the present invention, by adding a magnetic field generating coil, the problem caused by the misalignment of parallelism between the accelerating slit electrode and the output lift electrode during assembly can be eliminated to a minimum, and the time resolution can be improved. The decline can be prevented.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the sampling streak device of the present invention, Fig. 2 is a diagram for explaining the magnetic flux distribution generated by the magnetic field generating coil and the force acting on the beam, and Fig. 3 is a diagram showing the coil supply current and the force acting on the beam. Figure 4 shows the relationship between rotation angles, Figure 4 shows the luminescence detection pulse, Figure 5 shows the configuration of a conventional sampling streak tube, Figure 6 shows the deflection voltage waveform, and Figure 7 shows the acceleration. FIG. 2 is a diagram showing a conventional sampling streak tube using a slit electrode. l... Circular vacuum vessel, 2... Photocathode, 3... Mesh electrode, 4... Focusing electrode, 5... Anode plate, 6...
... Deflection electrode, 7... Output slit electrode, 8... Fluorescent surface, 9... High-speed repetitive pulsed light, lO... Acceleration slit electrode, 11... Linear photoelectron beam, 12...・
Photoelectrons due to thermoelectrons and stray light, 13... Linear photoelectron image formed on the slit electrode, 21... Magnetic field generation coil, 22... Coil power source, 23.24... Dcts,
25...Variable resistance. Applicant Hamamatsu Photonics Co., Ltd. Representative
Person Patent Attorney Masaru Hirukawa Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A sampling streak device characterized in that a magnetic field generating coil is arranged in a sampling streak tube, and a linear photoelectron beam is rotated in a plane perpendicular to the tube axis by passing a predetermined current through the coil. (2) The sampling streak device according to claim 1, wherein the magnetic field generating coil has a central axis that coincides with the tube axis. (3) The sampling streak device according to claim 1, wherein the magnetic field generating coil is arranged between a photocathode and an anode plate.