CN109406865A - A kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers - Google Patents
A kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers Download PDFInfo
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- CN109406865A CN109406865A CN201811391177.3A CN201811391177A CN109406865A CN 109406865 A CN109406865 A CN 109406865A CN 201811391177 A CN201811391177 A CN 201811391177A CN 109406865 A CN109406865 A CN 109406865A
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- dark current
- detection circuit
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- amplifier
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- 238000001514 detection method Methods 0.000 title claims abstract description 27
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000005187 foaming Methods 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims abstract description 8
- 229910052751 metal Inorganic materials 0.000 claims abstract description 8
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 7
- 239000003990 capacitor Substances 0.000 claims description 5
- 230000005294 ferromagnetic effect Effects 0.000 claims description 4
- 238000010998 test method Methods 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 description 6
- 230000005611 electricity Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000011797 cavity material Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
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- 238000005516 engineering process Methods 0.000 description 2
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- 238000010521 absorption reaction Methods 0.000 description 1
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- 238000004458 analytical method Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
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- 239000007769 metal material Substances 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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Abstract
The invention provides a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers, including electron multiplier and is connected to the cathode and anode power supply of its tube channel two sides.The dark current for detecting the electron multiplier in mass spectrometer is created through the invention, final ion concentration detection bring is influenced, the invention can monitor the dark current size of CEM electron multiplier in real time, the dark current voltage value of the anode supply directly obtained, convenient for accurately carrying out baseline deduction in subsequent circuit；Electro-magnetic shielding cover present invention employs foaming metal nickel as electron multiplier, it is effective to shield extraneous bring electromagnetic interference.
Description
Technical field
The invention belongs to circuit detection field, more particularly, to a kind of triple level four bars mass spectrograph electron multipliers
Dark current detection circuit.
Background technique
Triple quadruple mass-spectrometers are due to having the characteristics that highly sensitive, analysis speed is fast, amount of samples is few, as normal
The quantitative analytical instrument of rule is widely used in medicine, biology, chemical industry and environmental science.
Channel electron duplicator (Channel is usually used in the mass spectrometric signal deteching circuit of triple level four bars now
Electron Multiplier, CEM), this channel Electron Mltiplier be used for collect mass analyzer transmitting come it is to be detected from
Son, carries out electronics acceleration for ion in duplicator, forms current ion signal, which is introduced signal processing circuit
Carry out the detection of ion concentration.
Channel electron duplicator (Channel Electron Multiplier, CEM) is a kind of based on secondary electron hair
The novel continuous dynode electron multiplier part of principle is penetrated, it can directly detect the band such as neutral particle, electronics, ion can grain
Son does not need any conversion, efficiency with higher.CEM multi-purpose greatly now material is high pbo glass, the secondary hair of the material
Coefficient δ > 3 are penetrated, resistance is 108~1010 Ω, and chemical stability is good, is coated with fluxing agent and activation in inside pipe wall in glass inner wall
The material of resistivity appropriate and secondary emission rate is usually used in agent, to adapt to different application requirements, can be made straight spiral shell
Rotation, snail, " C " type.Pipe is placed in vacuum when use, its both ends add high pressure (1.8~3KV), pipe it is interior
Wall just becomes continuous dynode, and initial voltage is introduced from low side, hits after tube wall is released and excites secondary electron, these electronics are in electricity
Accelerate under the action of, goes out a large amount of secondary electron by collision excitation multiple in this way, so that the output end in channel obtains
Very big gain.
When its work, on the one hand since the baking of 380 DEG C~400 DEG C of high temperature must be born when channel electron duplicator, lead to
Temperature constantly increases in road；On the other hand, the pollution due to long-term work electron multiplier by atmospheric molecule, makes in channel
Generate adsorption layer；Even if electron multiplier is entered in no band energy particle, under the action of bias voltage, in the channel CEM
Fault location is produced from electricity subpulse, so as to form dark current, has eventually led to the raising of gain.However currently, market
In upper existing mass spectrograph product, lack the relevant technologies to the real-time monitoring of electron multiplier dark current.
Summary of the invention
In view of this, the invention is directed to a kind of dark current detection of triple level four bars mass spectrograph electron multipliers
Circuit monitors dark current by measuring circuit in real time, real-time according to dark current so as in subsequent signal processing circuit
Variation, baseline is deducted in corresponding setting, to eliminate dark current bring gain effects.
In order to achieve the above objectives, the technical solution of the invention is achieved in that
A kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers, including electron multiplier and difference
It is connected to the cathode and anode power supply of its tube channel two sides, it is characterised in that: the output end of the electron multiplier passes through a shielding line
With detection circuit data connection, the detection circuit includes current amplifier A1, feedback resistance RfAnd capacitor C1, the electronics increasing
The output end and current amplifier A of times device1Normal phase input end connection；Resistance RfOne end and current amplifier A1It is reversed defeated
Enter end connection, the other end and current amplifier A1Output end connection, the capacitor C1It is connected in parallel on resistance RfBoth ends.
Further, the cathode power use -6000V power supply or+4000V power supply；Anode supply, which uses, is higher than cathode
Voltage 1800~3000V power supply.
Further, the anode supply is the power supply that suspends.
Further, the outside of the electron multiplier is arranged shielding box.
Further, the shielding box is with ferromagnetic foaming metal nickel shielding box.
Further, the current amplifier A1For AD465 amplifier.
Compared with the existing technology, a kind of dark current of triple level four bars mass spectrograph electron multipliers described in the invention
Detection circuit has the advantage that
The dark current for detecting the electron multiplier in mass spectrometer is created through the invention, and final ion concentration is detected
Bring influences, and the invention can monitor the dark current size of CEM electron multiplier, the anode supply directly obtained in real time
Dark current voltage value, convenient for accurately carrying out baseline deduction in subsequent circuit；Present invention employs foaming metal nickel conducts
The electro-magnetic shielding cover of electron multiplier, it is effective to shield extraneous bring electromagnetic interference.
Detailed description of the invention
The attached drawing for constituting a part of the invention is used to provide to further understand the invention, present invention wound
The illustrative embodiments and their description made are used to explain the present invention creation, do not constitute the improper restriction to the invention.?
In attached drawing:
Fig. 1 is structural schematic diagram described in the invention embodiment；
Fig. 2 is detection circuit schematic diagram described in the invention embodiment.
Description of symbols:
1- electron multiplier；2- anode supply；3- cathode power；4- shielding box；5- shielding line；6- detection circuit.
Specific embodiment
It should be noted that in the absence of conflict, the feature in embodiment and embodiment in the invention can
To be combined with each other.
In the description of the invention, it should be noted that unless otherwise clearly defined and limited, term " peace
Dress ", " connected ", " connection " shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or integrally
Connection；It can be mechanical connection, be also possible to be electrically connected；Can be directly connected, can also indirectly connected through an intermediary,
It can be the connection inside two elements.For the ordinary skill in the art, on being understood by concrete condition
State concrete meaning of the term in the invention.
The present invention will be described in detail below with reference to the accompanying drawings and embodiments creates.
Dark current is an important indicator of channel electron duplicator, dark current refer to no signal or with can particle it is defeated
In the case where entering, the average value or D. C. value of electric current are generated in CEM output end, with symbol IdIt indicates.IdIt is divided into anode Id, cathode
Id, dynode Id.Since the avalanche effect of electronics (positive potential) can form a large amount of electronics at the anode of pipe, our usual institutes
The dark current said refers to the dark current of anode, therefore the invention measuring circuit mainly measures the dark current of anode.
As shown in Figure 1, a kind of dark current detection circuit 6 of triple level four bars mass spectrograph electron multipliers 1, including electronics increase
Times device 1 and it is connected to the cathode power 3 of its tube channel two sides, anode supply 2, the output end of the electron multiplier 1 is logical
A shielding line 5 and 6 data connection of detection circuit are crossed, the detection circuit 6 includes current amplifier A1, feedback resistance Rf, and electricity
Hold C1, the output end of the electron multiplier 1 is connect with the normal phase input end of current amplifier A1；One end of resistance Rf and electric current
The reverse input end of amplifier A1 connects, and the other end is connect with the output end of current amplifier A1, and the capacitor C1 is connected in parallel on
The both ends of resistance Rf.
3 use -6000V the power supply of cathode power or+4000V power supply；Anode supply 2 is using higher than cathode voltage 1800
~3000V power supply.
The anode supply 2 is the power supply that suspends.
The outside of the electron multiplier 1 is arranged shielding box 4.
The shielding box 4 is with ferromagnetic foaming metal nickel shielding box 4.
The current amplifier A1 is AD465 amplifier.
The working principle of the invention:
Wherein, two kinds of power supplys of 3 use -6000 of CEM cathode power or+4000V, are cut according to the negative ions to be detected
It changes；
CEM anode supply 2, the power supply use suspension mode, are higher than 1800~3000V of CEM cathode；
The shielding box 4 of channel electron duplicator 1, it is effective to shield extraneous bring electromagnetic interference, it avoids because of electromagnetic interference
Test result is influenced, shielding material uses ferromagnetic foaming metal nickel, and foaming metal is the cavity and metal material by being connected to
The porous material of skeleton composition, or on the surface layer and inner hole of cavernous body or organic foamed, metallic conduction processing is carried out,
Feature in structure is to make electromagnetic wave that multiple reflections and absorption loss occur in cavity, still reachable in the case where very thin thickness
To very high shield effectiveness, not only there is good electromagnetic wave shielding using foaming metal nickel but also to can satisfy precision assembly saturating
Gas heat dissipation；
Shielding line 5, anti-stop signal are interfered during transmission；
The detection circuit 6 of dark current, the circuit use Current amplifier type amplifier translation circuit, and current amplifier is hindered because of input
Resist low and response speed is higher, noise is lower, and signal-to-noise ratio is high, so being widely used in the transformation of low light signals.
As shown in Fig. 2, the output end of channel electron duplicator 1, accesses the in-phase end of operational amplifier AD645, operation is put
The input impedance of in-phase end and backward end in big device, that is, the load resistance of duplicator output end, are denoted as ZS, indicate are as follows:
ZS=Rf/ (A+1)
A is the amplification factor of operational amplifier AD645 open loop in above formula, and Rf is feedback resistance.As A=104, Rf=
1M Ω, ZS are 1 Ω；CEM output end is equivalent to short circuit at this time, the operational amplifier of Current amplifier state, output voltage Vo with it is defeated
Enter short-circuit dark current Id, direct proportionality:
Vo=Id × Rf
The variation of temperature can change the input current of amplifier, and the variation of the input current due to caused by temperature drift can be in feedback electricity
Biggish voltage drift is generated on resistance Rf, the shunt capacitance C1 on Rf, for bypassing the noise of generation, so that offset drift is brought
Error.Since tested dark current is Naan rank, operational amplifier is comprehensively considered using AD645.
Dark current test method:
(1) cathode power of electron multiplier is not opened, and AD645 amplifying circuit normal power supply obtains voltage Vo1, at this time for
The noise of amplifier；
(2) cathode power of electron multiplier, and AD645 amplifying circuit normal power supply are opened, voltage V is obtainedo2, at this time
Voltage is CEM anode IdWith the sum of the voltage of amplifier AD645 generation；
(3) pass through Vo2Subtract Vo1As Vo, VoFor anode dark current IdThe voltage value of generation.
This method is the dark current acquisition method of channel electron duplicator, by collected VoPass to next stage circuit progress
The baseline deduction of dark current.
The foregoing is merely the preferred embodiments of the invention, are not intended to limit the invention creation, all at this
Within the spirit and principle of innovation and creation, any modification, equivalent replacement, improvement and so on should be included in the invention
Protection scope within.
Claims (7)
1. a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers, including electron multiplier (1) and difference
Be connected to cathode power (3), the anode supply (2) of its tube channel two sides, it is characterised in that: the electron multiplier (1) it is defeated
For outlet by a shielding line (5) and detection circuit (6) data connection, the detection circuit (6) includes current amplifier A1, feedback
Resistance Rf and capacitor C1, the output end of the electron multiplier (1) are connect with the normal phase input end of current amplifier A1；Resistance
One end of Rf is connect with the reverse input end of current amplifier A1, and the other end is connect with the output end of current amplifier A1, institute
State the both ends that capacitor C1 is connected in parallel on resistance Rf.
2. a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers according to claim 1, special
Sign is: cathode power (3) use -6000V power supply or+4000V power supply；Anode supply (2) is using higher than cathode voltage
1800~3000V power supply.
3. a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers according to claim 2, special
Sign is: the anode supply (2) is the power supply that suspends.
4. a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers according to claim 1, special
Sign is: the outside of the electron multiplier (1) is arranged shielding box (4).
5. a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers according to claim 4, special
Sign is: the shielding box (4) is with ferromagnetic foaming metal nickel shielding box (4).
6. a kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers according to claim 1, special
Sign is: the current amplifier A1 is AD465 amplifier.
7. a kind of test method of dark current detection circuit of application as described in claim 1~6:
(1) cathode power of electron multiplier is closed, AD645 amplifying circuit normal power supply obtains voltage Vo1, it is at this time amplifier
Noise；
(2) cathode power of electron multiplier, and AD645 amplifying circuit normal power supply are opened, voltage V is obtainedo2, voltage at this time
For CEM anode IdWith the sum of the voltage of amplifier AD645 generation；
(3) pass through Vo2Subtract Vo1As Vo, VoFor anode dark current IdThe voltage value of generation.
(4) by collected VoPass to the baseline deduction that next stage circuit carries out dark current.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811391177.3A CN109406865A (en) | 2018-11-21 | 2018-11-21 | A kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811391177.3A CN109406865A (en) | 2018-11-21 | 2018-11-21 | A kind of dark current detection circuit of triple level four bars mass spectrograph electron multipliers |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4279510A (en) * | 1979-10-19 | 1981-07-21 | Beckman Instruments, Inc. | Spectrophotometer with improved photomultiplier tube dark signal compensation |
| US4310243A (en) * | 1979-10-19 | 1982-01-12 | Beckman Instruments, Inc. | Spectrophotometer with photomultiplier tube dark signal compensation |
| JP2006300728A (en) * | 2005-04-20 | 2006-11-02 | Hamamatsu Photonics Kk | Photodetection circuit and photodetector |
| CN106066397A (en) * | 2016-07-05 | 2016-11-02 | 深圳普门科技有限公司 | A kind of compensation system, method and immunity analysis instrument being applicable to current-output type photomultiplier tube |
| CN107110985A (en) * | 2014-12-18 | 2017-08-29 | 通用电气公司 | Silicon photomultiplier with internal calibration circuit |
| CN108120501A (en) * | 2017-11-22 | 2018-06-05 | 西安应用光学研究所 | A kind of faint illuminance measurement device of wide-range |
| CN209247876U (en) * | 2018-11-21 | 2019-08-13 | 天津国科医工科技发展有限公司 | A kind of dark current detection circuit of triple quadrupole mass spectrometer electron multiplier |
-
2018
- 2018-11-21 CN CN201811391177.3A patent/CN109406865A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4279510A (en) * | 1979-10-19 | 1981-07-21 | Beckman Instruments, Inc. | Spectrophotometer with improved photomultiplier tube dark signal compensation |
| US4310243A (en) * | 1979-10-19 | 1982-01-12 | Beckman Instruments, Inc. | Spectrophotometer with photomultiplier tube dark signal compensation |
| JP2006300728A (en) * | 2005-04-20 | 2006-11-02 | Hamamatsu Photonics Kk | Photodetection circuit and photodetector |
| CN107110985A (en) * | 2014-12-18 | 2017-08-29 | 通用电气公司 | Silicon photomultiplier with internal calibration circuit |
| CN106066397A (en) * | 2016-07-05 | 2016-11-02 | 深圳普门科技有限公司 | A kind of compensation system, method and immunity analysis instrument being applicable to current-output type photomultiplier tube |
| CN108120501A (en) * | 2017-11-22 | 2018-06-05 | 西安应用光学研究所 | A kind of faint illuminance measurement device of wide-range |
| CN209247876U (en) * | 2018-11-21 | 2019-08-13 | 天津国科医工科技发展有限公司 | A kind of dark current detection circuit of triple quadrupole mass spectrometer electron multiplier |
Non-Patent Citations (2)
| Title |
|---|
| 李昌厚 等: "光电倍增管暗电流的三种简易测试方法", 《光学仪器》, vol. 10, no. 1 * |
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Effective date of registration: 20220328 Address after: 300000 building 19, No. 16, Wujing Road, economic and Technological Development Zone, Dongli District, Tianjin Applicant after: Weigao Guoke mass spectrometry medical technology (Tianjin) Co.,Ltd. Address before: Building 4, No.16 Wujing Road, development zone, Dongli District, Tianjin Applicant before: TIANJIN GUOKE YIGONG TECHNOLOGY DEVELOPMENT Co.,Ltd. |