MCP (MICROCHANNEL PLATE) AND MCP ASSEMBLY

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OVERVIEW

MCP (microchannel plate) is a two-dimensional sensor that detects electrons, ions, vacuum UV rays, X-rays and gamma rays in a vacuum, and amplifies the detected signals. Circular and rectangular MCPs are available in various dimensions, including easy-to-use MCP assemblies with pre-mounted electrode leads and supports. These MCPs are widely used in many types of analytical equipment such as for “mass spectroscopy”, “semiconductor inspection” and “surface analysis”.
The MCP assemblies are available with three different readout devices to meet application needs. The devices are of: (1) single anode (electrical output signal measurement within effective area), (2) multianode (electrical output signal measurement correspond-ing to signal input positions), and (3) phosphor screen (optical imaging of output signal). Select the output device that best matches your application.
From one to three stage MCPs can be selected for the assembly to obtain necessary gain, allowing uses in the analog mode (the output signal is measured as a continuous electrical current) or the counting mode (the low level signal can be measured by a binary processing).

OPERATING PRINCIPLE

As shown in the figure on the lower right, a potential gradient is established along the channel when the voltage VD is applied be-tween the input and output sides of the MCP. Multiple secondary electrons are emitted when an electron enters a channel from the input side and strikes its inner wall. These secondary electrons are accelerated by the potential gradient to draw parabolic trajecto-ries that are determined by their initial velocities. They then strike the opposite wall in the channel causing further secondary elec-trons to be emitted. The electrons in this way travel towards the output end while striking the inner wall of the channel repeatedly. As a result, a large number of exponentially increased electrons are extracted from the output side.

IThickness

The thickness of an MCP is nearly equal to the channel length. The ratio of the channel length (L) to the channel diameter (d) is referred to as á (α=L/d), and this á and the secondary emission factor inherent to the channel wall material determine the gain of the MCP.
Standard MCPs are fabricated so that á is 40 to 60. The MCP thickness is therefore determined by the required chan-nel diameter and the design value of this á.

IOpen Area Ratio: OAR

The OAR indicates the ratio of the channel open area to the en-tire effective area of and MCP.

IBias angle

The bias angle is an angle formed by the channel axis and the axis perpendicular to the plate surface. This angle is chosen by considering the detection efficiency and spatial resolution as well as the prevention of input signals from passing through the chan-nels without colliding with the channel walls. The optimum value is usually from 5° to 15°.

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LARGE OAR: FUNNEL TYPE (OPTION)

The open area ratio (OAR) of standard MCPs is normally set to 60 %, but we also provide “funnel type” MCPs whose open area ratio is improved up to 90 % in order to guide more signals into each channel. Please contact us if you are interested in funnel type MCPs.

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CHARACTERISTICS

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MCP SPECIFICATIONS AND DIMENSIONAL OUTLINES
Circular MCP
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Rectangular MCP

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MCP ASSEMBLY SELECTION GUIDE BY PURPOSE

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MCP ASSEMBLY SELECTION GUIDE BY APPLICATIONS

Major applications of MCP assemblies include “mass spectroscopy”, “semiconductor inspection” and “surface analysis”.
The table below gives you a quick reference for selecting the best MCP assembly in these major application fields. This table shows only typical applications.
Feel free to contact our sales office in your area if you do not find your specific application here.

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MCP ASSEMBLY SPECIFICATIONS AND DIMENSIONAL OUTLINES (Unit: mm)

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Circular (Non-demountable)

Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.
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TYPE NUMBER DESIGNATION FOR NON-DEMOUNTABLE TYPE

The following ordering information applies only to circular MCP assemblies (non-demountable type). When ordering other MCPs (non-assembled MCPs) and MCP assemblies, use their type numbers as listed.
* When the customer prepares a read-out device, we supply MCP assemblies without readout devices.

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MCP ASSEMBLY SPECIFICATIONS AND DIMENSIONAL OUTLINES (Unit: mm)

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Circular (Demountable)
Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.

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PHOSPHOR SCREEN

Select the desired phosphor screen by taking into account the decay time according to the readout method and application, and the emission wavelength according to the readout device sensitivity.
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Rectangular (Demountable)
Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.

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TYPE NUMBER DESIGNATION FOR DEMOUNTABLE TYPE

The following ordering information applies only to circular/rectangular MCP assemblies (demountable type). When ordering other MCPs (non-assembled MCPs) and MCP assemblies, use their type numbers as listed.
* When the customer prepares a read-out device, we supply MCP assemblies without readout devices. If using a phosphor screen as the readout device, there is a need to change some points, so please consult us in advance.

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MCP ASSEMBLY SPECIFICATIONS AND DIMENSIONAL OUTLINES (Unit: mm)

 

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F4655
Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.

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F4655-14
Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.

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F2223-21SH
Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.

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F4294-09

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MCP ASSEMBLY SPECIFICATIONS AND DIMENSIONAL OUTLINES (Unit: mm)

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F9890-13/-14, F9892-13/-14

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F9890-31/-32, F9892-31/-32

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F4655-10/-13

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F4655-11

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MCP ASSEMBLY SPECIFICATIONS AND DIMENSIONAL OUTLINES (Unit: mm)

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F12334-11, F12395-11, F12396-11

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F2225-21PGF

Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa.
See page 9 regarding the phosphor screen.

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F6959

See page 9 regarding the phosphor screen.

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MCP ASSEMBLY WIRING EXAMPLES

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Using multiple high-voltage power supplies has an advantage that the MCP gain can be independently adjusted.
Using the divider circuit with a single high-voltage power supply offers low cost, but there is a disadvantage that the MCP gain varies as the power supply voltage varies.

CUSTOMIZATION

GWe also manufacture custom-designed MCPs and MCP assemblies not included in the standard product lineup. Please consult us with your specific requirements for outside dimensions, effective dimensions, thickness, etc. GFeel free to consult us on MCPs with a special aperture or through-hole (for use with reflection electron microscopes), CsI deposi-tion (for higher quantum efficiency in the VUV to X-ray range), aluminum film coating (as a barrier to ions and radiation), MgO coat-ing (for higher gain), electrodes made of Au (gold) and special-purpose MCPs. GFor multianodes, consult us on the desired anode pattern. GAssemblies with a phosphor-coated fiber optic plate (FOP) are available to enable fiber-coupling to solid state imaging devices (CCD, MOS linear image sensors), etc. GAssemblies with an MCP, readout device and lead terminals mounted on a special vacuum flange or printed circuit board are also available.
GPlease consult us regarding funnel type MCPs with an OAR of 90 %.

HOW TO HANDLE

1. STORAGE
The MCP and the MCP assembly are shipped in packages that are evacuated to a vacuum or filled with dry nitrogen. These packages are intended for use during shipping and not suited for long-term storage. When storing the MCP and MCP assemblies, take them out of their packages and keep them in a clean case under either a) or b) of the following conditions.
a) At vacuum pressure below 13 Pa and no oil diffusion.
b) Under gentle constant flow of dry nitrogen passed through a 0.45 µm or smaller filter (humidity: 20 % or less).

2. HANDLING
Avoid touching the MCP and the MCP assembly with bare hand. If handled with bare hand, these might be contaminated by oil and salt from it causing an increase in dark current, a loss of gain and an electrical discharge. When handling them, always wear clean vinyl or polyethylene gloves. Even when you wear gloves, never touch the effective area of the MCP and the MCP assembly.

3. ENVIRONMENTS
The MCP surface is processed to be electrically active and the components used for the assembly are also processed for high vacuum use. So as much as possible, handle them in an environment conforming to clean-room (dust-proof room) specifications where oily vapor, moisture and dust are minimized. If dusts or debris get on the MCP surface, blow them off with dry clean air or nitrogen gas. When doing this, check the pressure and surrounding area so as not to blow other dust into the air. Never use your own breath to blow off the dust from the MCP surface.

4. DEGASSING BEFORE USE
Gas adsorption usually occurs on the surface of an MCP which has not yet been used after delivery or has been stored after use. The MCP must be evacuated in a high vacuum below 1.3 × 10-4 Pa for more than 24 hours to perform degassing before using it (before supplying a voltage).

5. VACUUM BAKING
Vacuum baking is effective in degassing when the MCP or the MCP assembly is to be used in a high vacuum. Perform the vacuum baking under 150 °C while keeping the exhaust system at a vacuum pressure below 1.3 × 10-4 Pa. Vacuum baking cannot be performed on some types of MCP assembly. Please consult us for details.

6. SUPPLY VOLTAGE
Always maintain the MCP and the MCP assembly high vacuum condition below 1.3 × 10-4 Pa in operation. When supplying a voltage to the MCP or MCP assembly and to the output signal readout device (anode, phosphor screen), slowly increase it at every 100 V step (approx. 5 seconds per 100 V).

7. DISPOSAL METHOD
The materials in these products contain lead and its compound. Please follow the applicable regulations regarding disposal of hazardous materials and industrial wastes in your country, state, region or province.

WARRANTY PERIOD AND COVERAGE

This product is warranted for a period of one year from the date of shipment. If you find any failure or defect in the workmanship and notify us within this warranty period, we will repair or replace it free of charge. The warranty is limited to replacement of the defective product. Even if within the warranty period, this warranty shall not apply to failures or damages that were caused by the product reaching the end of its service life, incorrect operation, or accidents such as natural or man-made disasters.