JPH02142051A - Life indicating device for mcp - Google Patents

Abstract

PURPOSE:To make it possible to predict a time when a replacement of an MCP(micro-channel plate) is required by providing an output means for outputting a signal corresponding to an output current integration value of the MCP, and making an indication corresponding to its life based on the output signal. CONSTITUTION:For an MCP 1, a voltage of about 1KV is applied between electrodes 1a, 1b, and a charged particle 1d radiated to a microchannel 1c collides with a wall surface to be multiplied, and outputted from an anode 1e as a current. This output current is inputted to an amplifier which also performs current-voltage conversion, and a voltage outputted from the amplifier 2 is converted by a voltage/frequency converter 4 through a reduction filter 3 to be pulses of a corresponding number, which is counted by a counter 5. Since an output charge integration value of the MCP 1 corresponds to a relative advantage, the count value by the counter 5 is converted to a signal to indicate the relative advantage based on a predetermined expression by a data converter 6 and indicated at an indicator 7. Maintenance for replacement time, etc., can thus be achieved speedily and easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an MCP (microchannel plate) life display device.

[Conventional technology]

Image intensifier, ultraviolet rays, soft X-rays, electrons, ions, etc.
MCP (microchannel plate) is used to detect other charged particles.

MCP is a type of electron multiplier tube, and its structure is formed by forming many fine through holes of tens of micrometers in a thin plate of glass, and coating these through holes with a material that has electrical conductivity. The through holes are called microchannel plates (each of which functions as an electron multiplier), and Fe-Cr electrodes are deposited on both ends of the through holes.

Therefore, if a voltage is applied to the electrode to create a potential gradient in the axial direction of the microchannel, the electrons incident from one end of the microchannel will collide with the inner wall of the through hole and emit a large number of secondary electrons. These secondary electrons further collide with the inner wall and repeat the process of emitting secondary electrons several times,
These electrons are output from the other end of the through hole.

By the way, such an MCP has an output charge integrated value (C/
relative gain (%) according to the increase in c+1)...
- The initial value of MCP is 1, which is 100% at first. It has the characteristic of decreasing... That is, for example, when the output charge integrated value is 10-'C/cd, the relative gain is about 50%.

(Problem to be Solved by the Invention) However, in the past, there was no particular guide to the lifespan of an MCP, so it was necessary to measure the gain when necessary. , MCP must be stored in a vacuum, etc., which is not easy.
There was a problem in that management required unnecessary effort and cost.

[Means to solve problems]

In order to solve the above problems, the present invention provides output means (2, 3
, 4, 5, 6), and display means (7) for displaying a display according to the life of the MCP (1) based on the output signal of the output means. It is.

[For production]

According to the present invention, since a user can instantly grasp the lifespan of an MCP when necessary, it is possible to easily predict when it is necessary to replace the MCP.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention, in which an MCP
I is a charged particle 1d that is incident on the microchannel IC when a voltage of about IKV is applied between the electric currents ff1la and lb.
collides with the wall surface, multiplies, and is output as a current from the anode le. The output current of the MCPI thus obtained is input to an amplifier 2 that also performs current-voltage conversion, and is output as a voltage corresponding to the ft current output from the anode 1e. The voltage output from the amplifier 2 is input to a reduction filter 3 for extracting low frequency components, and the average voltage is output from the reduction filter 3. The average voltage output from the reduction filter 3 is converted by a voltage/frequency converter 4 into a corresponding number of pulses. ! The pulses converted by the pressure/frequency converter 4 are counted by the counter 5.

Since the count value of counter 5 corresponds to the integrated current output from MCPI, the count value of counter 5 is M
Corresponds to the output charge integrated value of CPI. And M.C.P.I.
Since the output charge integrated value corresponds to the relative gain, the count value of the counter 5 is converted by the data converter 6 into a signal representing the relative gain based on a predetermined arithmetic expression.

The output of the data converter 6 drives the display 7, so that
The relative gain is displayed on the display 7. Use # is indicator 7
You can instantly know the lifespan of MCPI just by looking at the relative gain of .

Note that the display on the display 7 does not necessarily need to display the relative gain as it is, but may be a display that corresponds to the relative gain. In other words, for example, the first use is set as 10, the period until the end of the life is set as 0, and the period between them is divided into 10 equal parts.
It is also possible to allocate numerical values from 9 to 9 and display those numerical values.

Moreover, the display according to the relative gain on the display 7 may be performed all the time, or may be performed only when necessary by switching a switch or the like.

Furthermore, the data converter 6 may be installed as a functional part in a computer for controlling a main unit such as an electron microscope in which the MCPI is used as a detector. data conversion work began. In this case, the data conversion work can be done by storing the relationship between the output charge integrated value (counter 5 count value) and relative gain in the memory in advance, and using the count value of counter 5 as the memory address command. relative gains can be obtained.

Of course, it not only simply displays the relative gain, but also warns you to prepare for MCPI exchange when the relative gain falls below 50%, and prompts MCPI to exchange when it falls below 20%. An alarm may be issued.

Furthermore, in the above explanation, the relative gain is set as a value according to the lifespan of the MCPI, and by displaying this value, the display is made according to the lifespan of the MCPI. (output current integrated value) as is
Even if it is displayed as a value corresponding to the CPI lifespan, it will not accumulate.

(Effects of the Invention) As described above, according to the present invention, an MCP user does not have to do the troublesome work of removing the MCP from the main body and remeasuring the gain while using the MCP. This allows maintenance such as replacement timing to be performed quickly and easily.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of the device according to the invention.

Claims (1)

[Claims] It is characterized by having an output means for outputting a signal according to the integrated value of the output current of the microchannel plate, and a display means for performing a display according to the lifespan of the microchannel plate based on the output signal of the output means. A lifespan display device for microchannel plates.