JP2002231179A - Vertical acceleration type time-of-flight mass spectrometric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an OA-TOFMS capable of avoiding burning of an electronic circuit caused by discharge between electrodes placed in a vacuum without using a lightening tube. SOLUTION: High speed switches are respectively provided between a first external power supply and a push electrode, between the push electrode and an earth electrode, between the earth electrode and a pull electrode, and between the pull electrode and a second external power supply, and a diode is connected to each high speed switch in parallel to the high speed switch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vertical acceleration time-of-flight mass spectrometer (OA-TOFMS; Orthogonal Acc.
OA-TOFMS, which can avoid burning of an electronic circuit due to a discharge between electrodes placed under vacuum, in particular,
About.

[0002]

2. Description of the Related Art OA-TOFMS introduces an ion beam from an ion source for continuously generating ions into an ion reservoir, and accelerates the ion beam in a pulse direction in a direction perpendicular to the ion beam introduction direction. This is a device for performing mass spectrometry by measuring the time-of-flight difference of each ion from immediately after acceleration until the ion is detected by the ion detector.

FIG. 1 schematically shows the configuration of an OA-TOFMS. In the figure, reference numeral 1 denotes an external ion source that continuously generates positive ions (or negative ions). Ion beam emitted by the acceleration potential V ₁ of the external ion source 1 positive (or negative) is a positive (or negative) converging lens 2 potential V _F is applied is converged in the Z direction, the y ₀ It is introduced into the ion reservoir 3 having an effective length.

A push electrode 4 having a ground potential is provided on a side wall portion of the ion reservoir 3 substantially in parallel with the central axis (Y axis) of the ion reservoir 3. Almost in parallel with the above, a grounded ground electrode 5 having a meshed ground potential and a pull electrode 6 also provided with a mesh and provided with a low potential having the same polarity as the polarity of ions are provided. During the period in which the ions are introduced from the external ion source 1, ions are not leaked from the ion reservoir 3 to the ground electrode 5 side.

In such a configuration, the push electrode 4
A positive voltage (or a negative voltage) pulse voltage 7 consisting of V _p1, when simultaneously applying a pulse voltage 8 consisting of a negative voltage (or positive voltage) V _p2 to pull the electrode 6, push the electrode 4 of the positive potential (or negative potential) A uniform electric field is instantaneously formed between the ground electrode 5 having a ground potential and the pull electrode 6 having a negative potential (or positive potential), and positive ions (or negative ions) accumulated in the ion reservoir 3 are formed. Ions) are simultaneously accelerated in the Z direction and ejected. The ejected ions are supplied to the accelerator tube 1 set to a negative potential (or a positive potential) V ₂ by the spectroscopic unit power supply 9.
After further accelerating at 0, it flies to the ion detector 11 composed of an MCP (micro channel plate) or the like. Strictly speaking, since the ions have a velocity in the Y direction when introduced into the ion reservoir 3, the ions in the Z direction are generated by the electric field generated between the push electrode 4, the ground electrode 5, and the pull electrode 6. Even if force is applied, the flight direction slightly deviates from the Z direction.

When the ions are subjected to the above acceleration, a constant energy corresponding to the potential difference between the push electrode 4 and the acceleration tube 10 is equally given to the ions. Larger ions have lower velocities. As a result of such a velocity difference, mass separation of the ions is performed while the ions fly in the acceleration tube 10 (in the time-of-flight spectroscopic unit), and the ions arrive at the ion detector 11 in order from the lightest ions, The spectrum is measured.

FIG. 2 shows a circuit configuration of a pulse power supply for supplying a positive (or negative) pulse voltage 7 to the push electrode 4 and a negative (or positive) pulse voltage 8 to the pull electrode 6 in such an OA-TOFMS. It is shown. The circuit is divided into a part for supplying a positive (or negative) pulse voltage 7 to the push electrode 4 and a part for supplying a negative (or positive) pulse voltage 8 to the pull electrode 6.

First, a pulse signal (output 0 to about 5 V, rising speed 30)
ns), the driving circuits 13, 14, 15, and 16
Respectively.

The drive circuit 13 outputs a pulse voltage faithfully corresponding to the pulse signal generated by the pulse generator 12 to the gate of a field effect transistor (FET) 17, and the source / drain of the FET 17 for a predetermined time width. Conduct between them. As a result, an external power supply (not shown)
A positive voltage + HV (approximately +800 V) supplied to the drain electrode is applied to the push electrode 4 via the positive / negative inversion relay 18 and the ringing prevention resistor 19 in a pulsed manner. In other words, the FET 17 functions as a high-speed switch for applying a pulse voltage to the push electrode 4.

The ringing preventing resistor 19 has a space between the push electrode 4 and the ground electrode 5 having a capacitance C,
A cable connecting the push electrode 4 and the FET 17 has an inductance L to form a resonance circuit, and functions to prevent generation of a transient oscillating current when the pulse voltage is turned on / off.

In parallel with the output of the pulse voltage from the drive circuit 13, the drive circuit 16
2 is output to the gate of the FET 20 in a form faithful to the pulse signal generated by the FE.
The source-drain of T20 is made conductive. As a result, a negative voltage −HV (about −800 V) supplied to the drain of the FET 20 from an external power supply (not shown) is applied to the pull electrode 4 via the positive / negative inversion relay 21 and the ringing prevention resistor 22 in a pulsed manner. . So to speak, FET20
Functions as a high-speed switch for applying a pulse voltage to the pull electrode 6.

The ringing preventing resistor 22 forms a resonance circuit by forming a space between the ground electrode 5 and the pull electrode 6 as a capacitance C, and a cable connecting the pull electrode 6 and the FET 20 as an inductance L to form a resonance circuit. At the time of ON / OFF, it functions to prevent generation of a transient oscillating current.

The positive / negative inversion relays 19 and 21 exchange the polarity of the pulse voltage applied to the push electrode 4 and the pull electrode 6 according to whether the ion to be analyzed is a positive ion or a negative ion. This is a kind of changeover switch provided for the purpose.

By the functions of the FETs 17 and 20, it becomes possible to simultaneously apply a pulse voltage of about 800 V having positive or negative mutually opposite polarities to the push electrode 4 and the pull electrode 6. But that's not all. In the case of only the two FETs described above, the fall of the voltage immediately after the application of the pulse voltage may become slow, so two more high-speed switches are provided to avoid this.

That is, the drive circuit 14 turns on / off the pulse signal generated by the pulse generator 12 while maintaining the faithful form.
Only the OFF timing is inverted and output to the gate of the FET 23, and the source and the drain of the FET 23 are cut off for a predetermined time width during which the pulse voltage is output to the push electrode 4. At other times, the source and the drain of the FET 23 are cut off. The drain is made conductive. As a result, the ground potential is changed to the positive / negative inverting relay 18 and the ringing prevention resistor 1 only during a time period when the positive voltage + HV (approximately +800 V) from the external power supply (not shown) is not applied to the push electrode 4.
Since it is set to the push electrode 4 via 9, the tailing can be avoided and the fall of the voltage immediately after the pulse voltage is applied can be sharpened.

In parallel with this, the driving circuit 15
Inverting only the ON / OFF timing while keeping the pulse signal generated by the pulse generator 12 faithful
24, the source-drain of the FET 24 is cut off for a predetermined time width during which the pulse voltage is output to the pull electrode 6, and the source-drain of the FET 24 is kept conductive in other time zones. . This allows
The ground potential is applied to the pull electrode 6 via the positive / negative inversion relay 21 and the ringing prevention resistor 22 only during a time period in which the negative voltage −HV (about −800 V) from the external power supply (not shown) is not applied to the pull electrode 6. Since it is set, tailing can be avoided and the fall of the voltage immediately after application of the pulse voltage can be sharpened.

The capacitors 25 and 26 are provided for lowering an AC component, which will be included in the DC voltages of two external power supplies (not shown), to the ground potential.

Also, four FETs, 17, 20, 23,
Since the voltages of the source terminals 24 have different values, it is necessary to employ the drive circuits 13, 14, 15, and 16 in which the input terminals and the output terminals are insulated.

[0019]

However, in such a configuration, the push electrode 4, the pull electrode 6, and the acceleration tube 10 are all placed close to each other in a vacuum, and the acceleration tube 1
0 is usually -7 kV (+7 kV when the analysis target is a negative ion)
V), the discharge from the accelerating tube 10 to the push electrode 4 and / or the pull electrode 6 is rarely caused due to contamination of the electrode by the sample or deterioration of the degree of vacuum. Had to wake up. Once discharge occurs, the potential of the electrode rises in a positive direction at a steep speed,
Or it descended in the negative direction, and the electronic circuit was sometimes burned under the influence of the lightning surge.

Therefore, in order to absorb the energy of this discharge and protect the electronic circuit from burning due to a lightning surge, a lightning arrester is provided between the push electrode 4 and the ground electrode 5 and between the pull electrode 6 and the ground electrode 5. When the potential difference between the respective electrodes exceeds the discharge starting voltage of the lightning arresters 27 and 28 due to the lightning surge, the lightning arresters 27 and 28 discharge to absorb the energy of the lightning surge, and the surrounding electronic circuits are provided. It was constructed so that the energy of the lightning surge would not be transmitted to the sea.

However, the lightning surge is so steep that the surge rising waveform dV / dt exceeds 100 V / μs, and if the response performance of the surge absorber is not good, the electronic circuit cannot be protected. The lightning arrester as a surge absorber has a problem that the discharge starting voltage changes due to a difference in the rising speed of the surge, so that it may not be possible to cope with a high-speed discharge. Further, in the pulse power supply of the OA-TOFMS, since a high-speed pulse of about 800 V is constantly generated, it is necessary to satisfy a condition of not discharging at about 800 V, and there is a problem that it is difficult to select a usable lightning arrester. . Further, since the lightning arrester is an element that converts discharge energy into heat, heat may be generated during use and characteristics may change, and there is a limitation that the number of times of use (the number of times of discharge) is limited.

In view of the above, an object of the present invention is to provide an OA that can avoid burning of an electronic circuit due to discharge between electrodes placed under vacuum without using a lightning arrester.
-To provide TOFMS.

[0023]

In order to achieve this object, an OA-TOFMS according to the present invention comprises an external ion source which continuously emits ions, and an ion beam which is emitted from the ion source. An ion reservoir in which an ion beam is introduced between the two electrodes, comprising a push electrode and a ground electrode arranged in parallel, and for accelerating ions in a direction perpendicular to the direction of ion beam introduction from the ion reservoir. A first external power supply that outputs a pulse voltage to the push electrode; and a second external power supply that outputs a pulse voltage having a polarity opposite to the pulse voltage in synchronization with the pulse voltage output to the push electrode. And a pulse voltage output from the second external power supply, which is disposed on the opposite side of the ground electrode from the push electrode and substantially parallel to the push electrode and the ground electrode. Time-of-flight spectroscopy that measures the time required for ions accelerated in the direction perpendicular to the ion beam introduction direction by the pulsed voltage applied to the push electrode and the push electrode to reach the ion detector. OA-TOFMS comprising: a portion between the first external power supply and the push electrode, a portion between the push electrode and the ground electrode, a portion between the ground electrode and the pull electrode, and a portion between the pull electrode and the second electrode. And a high-speed switch, and a diode is connected in parallel with the high-speed switch.

The high-speed switch provided between the first external power supply and the push electrode and the high-speed switch provided between the push electrode and the ground electrode are turned on / off at opposite timings. And a high-speed switch provided between the ground electrode and the pull electrode, and
The high-speed switch provided between the pull electrode and the second external power supply performs on / off operations at timings opposite to each other, and is provided between the first external power supply and the push electrode. The high-speed switch and the high-speed switch provided between the pull electrode and the second external power supply perform on / off operations at the same timing as each other, and are provided between the push electrode and the ground electrode. The high-speed switch, and the high-speed switch provided between the ground electrode and the pull electrode,
It is characterized in that it is configured to perform on / off operations at the same timing as each other.

Further, a ringing preventing resistor is provided between the push electrode and the high-speed switch and between the pull electrode and the high-speed switch.

Further, the high-speed switch is a field-effect transistor (FET).

Further, the polarity of the pulse voltage applied to the push electrode and the polarity of the pulse voltage applied to the pull electrode are set between the push electrode and the high-speed switch and between the pull electrode and the high-speed switch. It is characterized in that a changeover switch for switching is provided.

Further, a ringing prevention resistor is provided at both the front and rear stages of the changeover switch.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows OA- according to the present invention.
1 shows an embodiment of a pulse power supply of TOFMS. The power supply circuit is divided into a part for supplying a positive (or negative) pulse voltage 7 to the push electrode 4 and a part for supplying a negative (or positive) pulse voltage 8 to the pull electrode 6.

First, a pulse signal generated by the pulse generator 12 (output about 0 to 5 V, rising speed 30
ns), the driving circuits 13, 14, 15, and 16
Respectively.

The drive circuit 13 outputs to the gate of the field effect transistor (FET) 17 a pulse voltage faithful to the pulse signal generated by the pulse generator 12, and outputs the source / drain of the FET 17 for a predetermined time width. Conduct between them. As a result, an external power supply (not shown)
A positive voltage + HV (approximately +800 V) supplied to the drain electrode is applied to the push electrode 4 via the ringing prevention resistor 19 and the positive / negative inversion relay 18 in a pulsed manner. In other words, the FET 17 functions as a high-speed switch for applying a pulse voltage to the push electrode 4.

The ringing preventing resistor 19 has a capacitance C and a space between the push electrode 4 and the ground electrode 5.
A cable connecting the push electrode 4 and the FET 17 has an inductance L to form a resonance circuit, and functions to prevent generation of a transient oscillating current when the pulse voltage is turned on / off.

In parallel with the output of the pulse voltage from the drive circuit 13, the drive circuit 16
2 is output to the gate of the FET 20 in a form faithful to the pulse signal generated by the FE.
The source-drain of T20 is made conductive. As a result, a negative voltage −HV (about −800 V) supplied from an external power supply (not shown) to the drain of the FET 20 is applied to the pull electrode 4 in a pulsed manner via the ringing prevention resistor 22 and the positive / negative inversion relay 21. . So to speak, FET20
Functions as a high-speed switch for applying a pulse voltage to the pull electrode 6.

The ringing preventing resistor 22 forms a resonance circuit by forming a space between the ground electrode 5 and the pull electrode 6 as a capacitance C, and a cable connecting the pull electrode 6 and the FET 20 as an inductance L to form a resonance circuit. At the time of ON / OFF, it functions to prevent generation of a transient oscillating current.

The positive / negative inversion relays 19 and 21 exchange the polarity of the pulse voltage applied to the push electrode 4 and the pull electrode 6 according to whether the ion to be analyzed is a positive ion or a negative ion. This is a kind of changeover switch provided for the purpose.

By the functions of the FETs 17 and 20, it becomes possible to simultaneously apply a pulse voltage of about 800 V having positive or negative mutually opposite polarities to the push electrode 4 and the pull electrode 6. But that's not all. In the case of only the two FETs described above, the fall of the voltage immediately after the application of the pulse voltage may become slow, so two more high-speed switches are provided to avoid this.

That is, the drive circuit 14 turns on / off the pulse signal generated by the pulse generator 12 while maintaining the faithful form.
Only the OFF timing is inverted and output to the gate of the FET 23, and the source and the drain of the FET 23 are cut off for a predetermined time width during which the pulse voltage is output to the push electrode 4. At other times, the source and the drain of the FET 23 are cut off. The drain is made conductive. Accordingly, the ground potential is reduced to the ringing prevention resistor 19 and the positive / negative inverting relay 1 only during a time period when the positive voltage + HV (about +800 V) from the external power supply (not shown) is not applied to the push electrode 4.
Since it is set to the push electrode 4 via 8, it is possible to avoid tailing and sharpen the fall of the voltage immediately after the application of the pulse voltage.

In parallel with this, the driving circuit 15
Inverting only the ON / OFF timing while keeping the pulse signal generated by the pulse generator 12 faithful
24, the source-drain of the FET 24 is cut off for a predetermined time width during which the pulse voltage is output to the pull electrode 6, and the source-drain of the FET 24 is kept conductive in other time zones. . This allows
The ground potential is applied to the pull electrode 6 via the ringing prevention resistor 22 and the positive / negative inversion relay 21 only during a time period in which the negative voltage −HV (about −800 V) from an external power supply (not shown) is not applied to the pull electrode 6. Since it is set, tailing can be avoided and the fall of the voltage immediately after application of the pulse voltage can be sharpened.

The capacitors 25 and 26 are provided for lowering the AC component, which will be included in the DC voltages of two external power supplies (not shown), to the ground potential.

Also, four FETs, 17, 20, 23,
Since the voltages of the source terminals 24 have different values, it is necessary to employ the drive circuits 13, 14, 15, and 16 in which the input terminals and the output terminals are insulated.

In the present invention, instead of two lightning arresters, a mechanism for releasing the energy of a lightning surge is as follows.
Four high voltage diodes are used. That is, four F
Four high voltage diodes, 29, 30, 31, and 3, so as to be in parallel with ET, 17, 20, 23, and 24
2 respectively. Of these high voltage diodes,
Reference numeral 29 indicates a forward direction from the second external power supply toward the pull electrode, reference numeral 30 indicates a forward direction from the pull electrode to the ground electrode, and reference numeral 31 indicates a forward direction from the ground electrode to the push electrode. 32 are connected so as to be in the forward direction, respectively, and so as to be in the forward direction from the push electrode toward the first external power supply.

These high-voltage diodes operate as follows. First, a discharge occurs between the accelerating tube 10 and the push electrode 4, a positive lightning surge occurs on the push electrode 4, and the potential of the push electrode 4 becomes + HV (approximately +800 V) supplied by a first external power supply (not shown). Consider a case where the value exceeds the value in the positive direction. In that case, the potential of the push electrode 4 is higher than the potential of the first external power supply terminal (not shown), so that the positive / negative inversion relay 18 and the high voltage diode 29
, A current flows from the push electrode 4 to a first external power supply (not shown). Thereby, the energy of the lightning surge is absorbed, and burning of the FETs 17 and 23 is prevented beforehand. As a result of such an operation, the potential of the push electrode 4 does not exceed + 800V.

Next, a discharge occurs between the accelerating tube 10 and the push electrode 4, a negative lightning surge occurs at the push electrode 4, and the potential of the push electrode 4 exceeds the ground potential and becomes a negative value. Consider the case. In this case, since the potential of the ground terminal is higher than the potential of the push electrode 4, a current flows from the ground terminal to the push electrode 4 via the high voltage diode 30 and the positive / negative inversion relay 18. Thereby, the energy of the lightning surge is absorbed, and burning of the FETs 17 and 23 is prevented beforehand. As a result of such an operation, the potential of the push electrode 4 does not fall below 0V.

Next, a discharge occurred between the accelerating tube 10 and the pull electrode 6, and a positive lightning surge occurred at the pull electrode 6, and the potential of the pull electrode 4 exceeded the ground potential and became a positive value. Consider the case. In this case, since the potential of the pull electrode 6 is higher than the potential of the ground terminal, a current flows from the pull electrode 6 to the ground terminal via the positive / negative inversion relay 21 and the high voltage diode 31. As a result, the energy of the lightning surge is absorbed, and burning of the FETs 20 and 24 is prevented. As a result of such an operation, the potential of the pull electrode 6 becomes 0
It does not exceed V.

Next, a discharge occurs between the accelerating tube 10 and the pull electrode 6, a negative lightning surge occurs on the pull electrode 4, and the potential of the pull electrode 4 becomes a voltage supplied by a second external power supply (not shown). Consider a case where the value exceeds -HV (about -800 V) and becomes a negative value. In this case, the potential of the second external power supply terminal (not shown) is higher than the potential of the pull electrode 6. Therefore, the pull electrode is pulled from the second external power supply (not shown) via the high voltage diode 32 and the positive / negative inversion relay 21. The current flows toward 4. As a result, the energy of the lightning surge is absorbed, and burning of the FETs 20 and 24 is prevented. As a result of such an operation, the potential of the pull electrode 6 becomes -800 V
Never fall below.

Also, when the polarity of the pulse voltage applied to the push electrode 4 and the pull electrode 6 is inverted by switching the positive / negative inverting relays 18 and 21, the operation of the high voltage diode is exactly the same, and the lightning surge is reduced. Even if it occurs, current flows through the high-voltage diode, and there is no fear that the potential of the electrode will suddenly rise or fall beyond the above range,
The four FETs can be protected from burnout accidents due to lightning surge.

The push electrode 4 and the FETs 17 and 23
And a ringing preventing resistor 19 inserted between the pull electrode 6 and the FETs 20 and 24 have a role of preventing a discharge current from flowing into the FET. FET17,2
It also helps protect 0, 23, and 24.

In general, the capacitance between the push electrode 4 and the ground electrode 5 and the capacitance between the pull electrode 6 and the ground electrode 5 generally have slightly different values. This is because the acceleration tube 10 exists near the pull electrode 6. Since the pull electrode 6 has two electrodes (the ground electrode 5 and the accelerating tube 10) in the vicinity, the capacitance value is about twice as large as that of the push electrode 4.

Therefore, in order to make the pulse rise times of the push electrode 4 and the pull electrode 6 the same, it is necessary to reduce the ringing prevention resistance on the pull electrode 6 side. In the conventional pulse power supply shown in FIG. 2, the anti-ringing resistor is provided closer to the electrode than the positive / negative inverting relay. Therefore, even if the polarity of the electrode is inverted, the anti-ringing resistor does not change. Did not. However,
In the new pulse power supply shown in FIG.
In order to prevent inflow to the, the ringing prevention resistor is provided on the side closer to the FET than the high voltage diode.
There is a problem in that the ringing prevention resistor is replaced, and the resistance value of the ringing prevention resistor becomes opposite to the value of the capacitance of the electrode.

FIG. 4 shows an OA-
9 shows a modification of the pulse power supply of the TOFMS.
In this modification, the anti-ringing resistor is divided and divided into a former stage and a latter stage of the positive / negative inverting relays 18 and 21, and separately provided anti-ringing resistors. It is configured so that it can be adjusted to the value. This solves the problem of inconsistency in the resistance of the anti-ringing resistor when the polarity of the electrode is reversed.

[0051]

As described above, the OA-TO of the present invention is used.
According to the FMS, between the first external power supply and the push electrode, between the push electrode and the ground electrode, between the ground electrode and the pull electrode, and between the pull electrode and the second external power supply,
Each has a high-speed switch, and for each high-speed switch,
Since the diodes are connected in parallel with each high-speed switch, an OA-TOFMS that can avoid burning of an electronic circuit due to discharge between electrodes placed under vacuum without using a lightning arrester is provided. It became possible to provide.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional vertical acceleration time-of-flight mass spectrometer.

FIG. 2 is a diagram showing a pulse power source of a conventional vertical acceleration time-of-flight mass spectrometer.

FIG. 3 is a diagram showing one embodiment of a pulse power source of the vertical acceleration time-of-flight mass spectrometer according to the present invention.

FIG. 4 is a diagram showing another embodiment of the pulse power source of the vertical acceleration time-of-flight mass spectrometer according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... External ion source, 2 ... Convergent lens, 3 ... Ion reservoir, 4 ... Push electrode, 5 ... Ground electrode, 6 ... Pull electrode, 7 ... Pulse voltage, 8: pulse voltage, 9: power supply of spectroscopic unit, 10: acceleration tube, 11: ion detector, 12 ...
Pulse generator, 13 ... Drive circuit, 14 ... Drive circuit, 1
5 ... Drive circuit, 16 ... Drive circuit, 17 ... FET, 1
8: positive / negative inversion relay, 19: ringing prevention resistor, 2
0 ... FET, 21 ... Positive / negative inverting relay, 22 ... Ringing prevention resistor, 23 ... FET, 24 ... FET, 25 ...
・ Condenser, 26 ・ ・ ・ Condenser, 27 ・ ・ ・ Surge arrester, 2
8 arrester, 29 high-voltage diode, 30 high-voltage diode, 31 high-voltage diode, 32 high-voltage diode.

Claims (7)

[Claims] 1. An external ion source which continuously emits ions, a push electrode and a ground electrode which are arranged substantially in parallel with an ion beam emitted from the ion source interposed therebetween, and are provided between two electrodes. An ion reservoir into which an ion beam is introduced, a first external power supply that outputs a pulse voltage to a push electrode to accelerate ions from the ion reservoir in a direction orthogonal to an ion beam introduction direction, In synchronization with the pulse voltage output to the push electrode, a second external power supply that outputs a pulse voltage having a polarity opposite to the pulse voltage, and a push electrode and a push electrode on the opposite side of the ground electrode from the push electrode. A pull electrode, which is disposed substantially parallel to the ground electrode and to which a pulse voltage output from the second external power supply is applied, and a pulse voltage applied to the push electrode and the pull electrode. A vertical acceleration time-of-flight mass spectrometer comprising a time-of-flight spectroscopic unit that measures the time of flight until ions accelerated in the direction orthogonal to the ion beam introduction direction reach the ion detector, A high-speed switch is provided between the first external power supply and the push electrode, between the push electrode and the ground electrode, between the ground electrode and the pull electrode, and between the pull electrode and the second external power supply. A vertical acceleration time-of-flight mass spectrometer, wherein a diode is connected in parallel with the high-speed switch. 2. The diode has a forward direction from a second external power supply toward a pull electrode, a forward direction from a pull electrode to a ground electrode, and a forward direction from a ground electrode to a push electrode. 2. The vertical acceleration time-of-flight mass spectrometer according to claim 1, wherein the vertical acceleration type time-of-flight mass spectrometer is connected to the first external power supply from the push electrode. 3. A high-speed switch provided between the first external power supply and the push electrode and a high-speed switch provided between the push electrode and the ground electrode are turned on / off at timings opposite to each other. The high-speed switch provided between the ground electrode and the pull electrode and the high-speed switch provided between the pull electrode and the second external power supply are turned on / off at opposite timings. The high-speed switch that performs an OFF operation and is provided between the first external power supply and the push electrode, and the high-speed switch that is provided between the pull electrode and the second external power supply are the same as each other. The high-speed switch provided between the push electrode and the ground electrode and the high-speed switch provided between the ground electrode and the pull electrode are turned on / off at the same timing. / Off vertical acceleration type according to claim 1 or 2, wherein it is configured to the operation of the time-of-flight mass spectrometer. 4. The method according to claim 1, further comprising the step of:
And a ringing preventing resistor is provided between the pull electrode and the high-speed switch.
4. The vertical acceleration time-of-flight mass spectrometer according to 2 or 3. 5. The high speed switch according to claim 1, wherein said high speed switch is a field effect transistor (FET).
5. The vertical acceleration time-of-flight mass spectrometer according to 3 or 4. 6. A method according to claim 6, wherein said push electrode and said high-speed switch are provided between:
A switch is provided between the pull electrode and the high-speed switch for switching the polarity of the pulse voltage applied to the push electrode and the polarity of the pulse voltage applied to the pull electrode. Claim 1,
6. The vertical acceleration time-of-flight mass spectrometer according to 2, 3, 4, or 5. 7. The vertical acceleration time-of-flight mass spectrometer according to claim 6, wherein a ringing preventing resistor is provided at both the front and rear stages of the changeover switch.