JPH08185805A - High frequency electron gun - Google Patents

Abstract

PURPOSE: To provide a high frequency electron gun by which a large electric current can be obtained by eliminating a limit to electron emission due to restriction of a temperature. CONSTITUTION: This high frequency electron gun is provided with a first resonant cavity 2, a second resonant cavity 3, a drift space 61 to connect the first resonant cavity 2 and the second resonant cavity 3 to each other, an emitting port 62 connected to the second resonant cavity 3, a cathode tube 63 which is connected to the side opposed to the drift space 61 of the first resonant cavity 2 and houses a cold cathode chip 10 and a wave guide 4 connected to the first resonant cavity 2. The cold cathode chip 10 is arranged as an electron emitting source instead of a conventional hot cathode, and is supported by a support member 5. The wave guide 4 guides a wave of a high frequency electric field 41 supplied from an unillustrated high frequency generating source, and supplies it into the first resonant cavity 2. The cold cathode chip 10 is provided with a conductive or semi-conductive base board and conductive microscopic negative electrodes which are arranged in a large number on this board and have conical shapes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun used in an electron accelerator or the like, and more particularly to a high frequency electron gun which generates a high energy electron beam by utilizing high frequency resonance.

[0002]

2. Description of the Related Art Conventionally, in this type of high frequency electron gun, a hot cathode is used as an electron emission source, and the hot cathode is heated by a heater to extract thermoelectrons.

FIG. 11 shows a conventional high frequency electron gun together with a partial cross section. This high-frequency electron gun is connected to the first resonance cavity 2, the second resonance cavity 3, a drift space 61 connecting the first resonance cavity 2 and the second resonance cavity 3, and the second resonance cavity 3. And a cathode tube 63 that is connected to the side of the first resonance cavity 2 that faces the drift space 61 and that accommodates the thermal cathode 8, and a waveguide 4 that is connected to the first resonance cavity 2. ing. Hot cathode 8
Is supported by a support member 5 and is heated from behind by a heater 6 which generates heat by an electric current supplied from a DC power supply 7. The waveguide 4 is for guiding the high frequency electric field 41 supplied from a high frequency voltage generation source (not shown) and supplying the high frequency electric field 41 into the first resonance cavity 2.

The operation of the conventional high frequency electron gun having the above structure will be described with reference to FIG. A current is supplied from the DC power supply 7 to the heater 6 to heat the heater 6, and the hot cathode 8 is heated from the back to a predetermined temperature. Here, when the high frequency electric field 41 is supplied from the waveguide 4 into the first resonance cavity 2, a high frequency electric field 42 is generated between the nose 40 of the first resonance cavity 2 and the hot cathode 8, and thereby the hot cathode 8 is generated.
From which thermoelectrons are extracted to form a convergent electron beam, which is accelerated. The electrons accelerated in the first resonance cavity 2 pass through the drift space 61 and into the second resonance cavity 3 where they are further accelerated. Then, the high energy electron beam 43 is emitted from the emission port 62. This conventional example is disclosed in, for example, Japanese Patent Publication No. 58-20120.

[0005]

As described above, since the conventional high-frequency electron gun uses the hot cathode as an electron emission source, only "temperature-limited electrons" determined by the material and temperature of the hot cathode are extracted. I couldn't accelerate. For this reason, there is a problem that the extraction ability by the high frequency electric field cannot be fully utilized and a large current cannot be obtained.

The present invention has been made in view of the above problems, and an object thereof is to provide a high frequency electron gun capable of obtaining a large current without the limit of electron emission due to temperature limitation.

[0007]

A high frequency electron gun according to claim 1 is a high frequency electron gun having an accelerating tube for accelerating electrons, wherein electrons are extracted along the accelerating tube,
A cold cavity provided with a resonance cavity formed for converging and accelerating, a substrate provided at one end of the axis body of the acceleration tube in the resonance cavity, and a plurality of microcathodes formed on the substrate. A cathode chip and a high frequency electric field supply means for supplying a high frequency electric field for extracting electrons from the micro cathode of the cold cathode chip are provided in the resonance cavity.

A high frequency electron gun according to a second aspect is the first aspect.
In the high frequency electron gun described above, a gate electrode for controlling emitted electrons from the microcathode is further arranged on the substrate of the cold cathode chip.

A high frequency electron gun according to a third aspect is the second aspect.
The high frequency electron gun described above further includes a DC power supply for applying a DC voltage between the microcathode and the gate electrode.

A high frequency electron gun according to a fourth aspect is the second aspect.
The high frequency electron gun described above further includes a pulse voltage generation source for applying a pulse voltage between the microcathode and the gate electrode.

A high frequency electron gun according to a fifth aspect is the second aspect.
The high-frequency electron gun described above further includes a high-frequency voltage generation source that applies a high-frequency voltage between the microcathode and the gate electrode.

A high frequency electron gun according to a sixth aspect is the second aspect.
The high-frequency electron gun according to claim 1, further comprising a phase difference providing unit that provides a phase difference between a high-frequency voltage applied between the microcathode and the gate electrode and a high-frequency electric field supplied into the resonant cavity. It is a thing.

A high frequency electron gun according to a seventh aspect is the second aspect.
In the high-frequency electron gun described above, further, frequency multiplication means for multiplying the frequency of the high-frequency voltage applied between the microcathode and the gate electrode to an integral multiple of the frequency of the high-frequency electric field supplied into the resonant cavity. Be prepared.

[0014]

In the high frequency electron gun according to the present invention, the cold cathode chip having a large number of microcathodes formed on the substrate by using vacuum microelectronics is used instead of the conventional hot cathode. There is no limit.

In the high frequency electron gun according to the second aspect, by arranging the gate electrode on the substrate, the amount of electrons emitted from the microcathode can be controlled.

In the high frequency electron gun according to the third aspect, the amount of emitted electrons is controlled by the DC voltage applied between the micro cathode and the gate electrode.

In the high frequency electron gun according to the fourth aspect, the amount of emitted electrons is controlled by the pulse voltage applied between the microcathode and the gate electrode.

In the high frequency electron gun according to the fifth aspect, the amount of emitted electrons is controlled by the high frequency voltage applied between the micro cathode and the gate electrode.

In the high frequency electron gun according to the sixth aspect, a pulse corresponding to a phase difference between a high frequency voltage applied between the microcathode and the gate electrode and a high frequency electric field supplied in the resonant cavity. A wide electron beam is obtained.

In the high frequency electron gun according to the seventh aspect, an electron beam having a pulse width corresponding to the multiplication order by the frequency multiplication means can be obtained.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a structure of a high frequency electron gun according to an embodiment of the present invention. The same components as those in the conventional example are designated by the same reference numerals. This high frequency electron gun is the first
The resonance cavity 2, the second resonance cavity 3, and the drift space 61 connecting between the first resonance cavity 2 and the second resonance cavity 3.
An emission opening 62 connected to the second resonance cavity 3, a cathode tube 63 connected to the side of the first resonance cavity 2 facing the drift space 61 and accommodating the cold cathode chip 10, and a first resonance cavity 2 And a waveguide 4 connected to. The cold cathode chip 10 is provided as an electron emission source instead of the hot cathode 8 of the conventional example (FIG. 11), and is supported by the support member 5. The waveguide 4 is for guiding the high frequency electric field 41 supplied from a high frequency generating source (not shown) and supplying the high frequency electric field 41 into the first resonance cavity 2.

FIG. 2 shows an enlarged cross section of the cold cathode chip 10 of FIG. The cold cathode chip 10 includes a conductive or semi-conductive substrate 11 and a large number of conductive micro-cathodes 12 arranged on the substrate 11 and having a conical shape. This micro cathode 12 is disclosed in, for example, Japanese Patent Laid-Open No. 6-3.
By using the vacuum microelectronics technology disclosed in Japanese Patent No. 6681, it is formed with an areal density of about 1.0 × 10 ⁷ pieces / cm ² .

The operation of the high frequency electron gun having the above configuration will be described. When a high-frequency electric field 41 output from a high-frequency generator (not shown) is supplied from the waveguide 4 into the first resonance cavity 2, the TM01 resonance mode causes the high-frequency electric field in the axial direction in the first resonance cavity 2, that is, a half cycle of high frequency. An acceleration electric field and a deceleration electric field are alternately generated every time. Cold cathode chip 10
Emits electrons during the accelerated electric field. Specifically, a high electric field is generated at the tip of the microcathode 12, and electrons (current) of several tens of μA (microamperes) are emitted per microcathode 12. The electrons emitted from each microcathode 12 become a focused electron beam and are accelerated in the first resonance cavity 2. First
The electrons accelerated in the resonance cavity 2 are transferred to the drift space 61.
Through and into the second resonant cavity 3, where it is further accelerated. Then, the high energy electron beam 43 is emitted from the emission port 62.

Here, assuming that the electrons emitted from one microcathode 12 are, for example, 30 μA, the current I per unit area is given by the following equation (1), and the space charge limiting region is almost limited. A large current close to is obtained.

I = 30 [μA / piece] × 1 × 10 ⁷ [piece / cm ² ] = 300 [A / cm ² ] ... (1) FIG. 3 shows high frequency electrons according to the second embodiment of the present invention. It shows the configuration of the main part of the gun. The same components as those in the above embodiment (FIG. 2) are designated by the same reference numerals. This high frequency electron gun includes a conductive or semi-conductive substrate 11 and the substrate 11.
Conductive micro-cathode 1 having a large number of cones and having a conical shape
2 and a cold cathode chip 1 provided with a large number of minute gate electrodes 14 arranged on the substrate 11 via minute insulating layers 13.
It has 0 '. Each gate electrode 14 is formed between adjacent microcathodes 12 so as to maintain an insulating state between the substrate 11 and the microcathode 12. The formation of the gate electrode 14 is also performed by utilizing the vacuum microelectronics technology. Gate electrode 14 of cold cathode chip 10 '
Is connected to the positive side of the DC power supply 15 and the substrate 11 is connected to the negative side,
A direct current voltage is applied between the gate electrode 14 and the substrate 11. Other configurations are the same as those in FIG.

The operation of the high frequency electron gun configured as described above will be described. Also in this high-frequency electron gun, the basic operation is the same as in the above embodiment. That is, the high frequency electric field 41
Is supplied from the waveguide 4 into the first resonance cavity 2, a high-frequency electric field is generated in the first resonance cavity 2 in the axial direction by the TM01 resonance mode, and a high electric field is generated at the tip of the microcathode 12 of the cold cathode chip 10 '. Occurs. Therefore, electrons are emitted from the tip of the microcathode 12 during the high-frequency acceleration electric field.

On the other hand, the gate electrode 1 of the cold cathode chip 10 '
Since 4 is held at a positive potential by the DC power supply 15, some of the electrons emitted from the microcathode 12 are captured by the gate electrode 14. Since the trapped amount in this case depends on the potential of the gate electrode 14 with respect to the substrate 11 (that is, the microcathode 12), by appropriately setting the voltage of the DC power supply 15, the voltage can be passed between the gate electrodes 14 and the first resonance cavity. Two
The amount of electrons emitted inside (that is, the size of the electron flow 50)
Can be adjusted.

The electrons passing between the gate electrodes 14 become a focused electron beam and are accelerated in the first resonant cavity 2 and then further accelerated in the second resonant cavity 3 to generate a high-energy electron beam from the emission port 62. It is emitted as 43.

Thus, according to this embodiment, the substrate 11
By applying an appropriate DC voltage between the gate electrode 14 and the gate electrode 14, a required amount of current can be taken out. Therefore, if the DC power supply 15 is a variable voltage power supply, the magnitude of the extracted current can be freely adjusted from a small current to a large current. Furthermore, by drawing out electrons by a high frequency electric field, an electron gun with low emittance can be constructed.

FIG. 4 shows the essential structure of a high frequency electron gun according to the third embodiment of the present invention. The same components as those in the above embodiment (FIG. 3) are designated by the same reference numerals. This high frequency electron gun includes a cold cathode chip 10 'having the same structure as the cold cathode chip 10' shown in FIG. However, in this embodiment, a pulse generator 16 for generating a pulse voltage is provided instead of the DC power supply 15 of FIG. The pulse generator 16 uses a 50Ω transmission line 17 to cool the cold cathode chip 10 '.
Of the substrate 11 and the gate electrode 14. 5
The 0 Ω transmission line 17 is for transmitting the voltage and the waveform of the pulse generated by the pulse generator 16 without damaging the pulse, so that the pulse is generated between the substrate 11 of the cold cathode chip 10 ′ and the gate electrode 14. The pulse voltage of the waveform as it is output from the generator 16 is applied. Other configurations are the same as those in FIG.

The operation of the high frequency electron gun having the above configuration will be described. In this high frequency electron gun, the cold cathode chip 10 '
Since the gate electrode 14 has a positive potential in a pulsed manner, the electrons emitted from the microcathode 12 are captured in a pulsed manner by the gate electrode 14. Therefore, the pulse generator 1
By appropriately setting the magnitude and pulse width of the pulse voltage output from 6, the amount of electrons emitted into the first resonant cavity 2 can be determined.

As described above, in this embodiment, a required amount of current can be taken out with a required pulse width, and if the magnitude and pulse width of the pulse voltage are made variable, a small current to a large current can be freely set. The current can be extracted with a short pulse. Furthermore, a short pulse electron gun with low emittance can be constructed by drawing out electrons by a high frequency electric field.

FIG. 5 shows a main configuration of a high frequency electron gun according to a fourth embodiment of the present invention. The same components as those in the above embodiment (FIG. 4) are designated by the same reference numerals. This high-frequency electron gun includes a cold cathode chip 10 'having the same structure as the cold cathode chip 10' shown in FIG. However, in this embodiment, a high frequency generator 18 for generating a sinusoidal high frequency voltage is provided instead of the pulse generator 16 of FIG.
The high frequency generator 18 is connected to the substrate 11 and the gate electrode 14 of the cold cathode chip 10 ′ by the 50Ω transmission line 17. Then, the substrate 11 of the cold cathode chip 10 '
The high-frequency voltage having the waveform as output from the high-frequency generator 18 is applied between the gate electrode 14 and the gate electrode 14. Other configurations are the same as those in FIG.

The operation of the high frequency electron gun configured as described above will be described. In this high frequency electron gun, the high frequency generator 18
Cold cathode chip 1 by high frequency voltage applied by
Since the 0'gate electrode 14 has a positive potential alternately in a sinusoidal shape, the electrons emitted from the microcathode 12 are emitted from the gate electrode 1
4 is captured in a sinusoidal proportion. Therefore,
By appropriately setting the magnitude and frequency of the high frequency voltage output from the high frequency generator 18, the amount of electrons emitted into the first resonant cavity 2 can be determined.

As described above, according to the present embodiment, a required amount of current can be taken out in a sinusoidal waveform at a required frequency, and if the amplitude and frequency are variable, the sine current can be freely changed from a small current to a large current. The current can be taken out with a wave waveform. Furthermore, a short pulse electron gun with low emittance can be constructed by drawing out electrons by a high frequency electric field. Further, since the high frequency generator 18 can be constructed more simply and cheaper than the pulse generator 16 in the third embodiment (FIG. 4) described above, the cost increase of the high frequency electron gun can be suppressed.

FIG. 6 shows the essential structure of a high-frequency electron gun according to the fifth embodiment of the present invention. The same components as those in the above embodiment (FIGS. 1 and 5) are designated by the same reference numerals. This high frequency electron gun includes a reference signal generator 20 for generating a high frequency signal having a predetermined frequency, and the reference signal generator 20.
Of the high-frequency signal output from the reference signal generator 20, the phase shifter 22 connected to the output terminal of the high-frequency amplifier 21, and the output of the phase shifter 22. A circulator 23 connected to the end and a dummy load 24;
Of the cold cathode chip 10 ′ connected to the output end of the 50 Ω transmission line 17, the klystron 26 connected to the output end of the high frequency amplifier 25, and the dummy load 28 connected to the output end of the klystron 26. And a circulator 27.

The phase shifter 22 is for shifting the output of the high frequency amplifier 21 by a predetermined phase with respect to the input,
For example, it is composed of an LC phase shift circuit. Circulator 23
Is for rotating the plane of polarization of the output of the phase shifter 22, and a high frequency electric field applied to the cold cathode chip 10 'by the 50Ω transmission line 17 causes a reflected wave due to impedance mismatch in the cold cathode chip 10'. When it occurs, the reflected wave is returned toward the dummy load 24 so that the high frequency amplifier 21 is not affected. Further, the circulator 27 returns the reflected wave in the direction of the dummy load 28 when the high frequency electric field applied to the first resonance cavity 2 via the waveguide 4 causes the reflected wave due to impedance mismatch. This is to prevent the high frequency amplifier 25 from being affected. Dummy load 24,2
Reference numeral 8 is provided to consume the energy of the reflected wave. The klystron 26 is a kind of microwave vacuum tube, and is a large gain amplifier also called a velocity modulation tube.
The cold cathode chip 10 'is the cold cathode chip 10' shown in FIG.
The substrate 11 and the gate electrode 14 of this cold cathode chip 10 ′ are connected to the circulator 23 by the 50Ω transmission line 17 in the same structure as in FIG. Other configurations are the same as those in FIG.

The operation of the high frequency electron gun configured as described above will be described. The high frequency amplifier 21 amplifies the reference high frequency signal generated by the reference signal generator 20 and inputs it to the phase shifter 22. The phase shifter 22 controls the phase of the high frequency signal to be shifted by a preset phase, and the phase-shifted high frequency signal is transmitted through the circulator 23 to the 50Ω transmission line 1.
7 supplies to the cold cathode chip 10 'without loss of waveform. As a result, a high frequency voltage is applied between the micro cathode 12 of the cold cathode chip 10 'and the gate electrode 14 (FIG. 5). At this time, the reflected wave reflected by the cold cathode chip 10 ′ is sent to the dummy load 24 by the circulator 23 and is prevented from returning to the high frequency amplifier 21.

On the other hand, the high frequency amplifier 25 amplifies the reference high frequency signal generated by the reference signal generator 20 and inputs it to the klystron 26. The klystron 26 further amplifies the amplified reference high frequency signal, and supplies the high frequency high frequency electric field 41 into the first resonance cavity 2 by the waveguide 4. At this time, the reflected wave reflected by the first resonance cavity 2 is sent to the dummy load 28 by the circulator 27 and is prevented from returning to the klystron 26.

In this embodiment, the cold cathode chip 10 'is used.
Although the phase of the high-frequency voltage applied to the first resonance cavity 2 is shifted by the phase shifter to give a phase difference to the high-frequency electric field in the first resonance cavity 2, the present invention is not limited to this. The phase of the high frequency electric field supplied to the inside of 2 may be shifted. In this case, the phase shifter 22
6 may be removed from the position of FIG. 6 and may be provided between the high frequency amplifier 25 and the klystron 26, for example.

FIG. 8 shows the operation of this high-frequency electron gun. FIG. 8A shows the electric field waveform in the first resonance cavity 2,
(B) shows an electric field waveform between the micro cathode 12 and the gate electrode 14 of the cold cathode chip 10 ′, and (c) shows a current waveform accelerated and emitted from the first resonant cavity 2. As shown in this figure,
Both the electric field of the first resonance cavity 2 (Fig. (A)) and the gate-emitter electric field of the cold cathode chip 10 '(Fig. (B)) are positive electric fields (electric fields in the direction of emitting and accelerating electrons). Only during this period, electrons are emitted and accelerated from the first resonance cavity 2 ((c) in the figure). The electrons emitted from the first resonance cavity 2 in this way are further accelerated in the second resonance cavity 3 and emitted as a high-energy electron beam 43 from the emission port 62. The pulse width of this high energy electron beam 43 is
It is determined by the amount of phase shift by the phase shifter 22.

As described above, in this embodiment, the first resonance cavity 2
To the phase of the high frequency electric field 41 to the cold cathode chip 10 '
Since the pulse width of the current taken out from the cold cathode chip 10 'can be set by phase-shifting the high-frequency electric field between the gate and the emitter of, the phase shift amount in the phase shifter 22 is finely adjusted as shown in FIG. It becomes easy to output an electron beam having a shorter pulse width than the case.

FIG. 7 shows a main structure of a high frequency electron gun according to a sixth embodiment of the present invention. The same components as those in the above embodiment (FIGS. 1 and 5) are designated by the same reference numerals. This high frequency electron gun includes a reference signal generator 20 for generating a high frequency signal having a predetermined frequency, and the reference signal generator 20.
30 which is connected to the output terminal of and outputs the frequency of the high frequency signal output from the reference signal generator 20 by an integer multiple
And the phase shifter 22 connected to the output terminal of the multiplier 30
And the high frequency amplifier 21 connected to the output end of the phase shifter 22.
A circulator 23 connected to the output end of the high frequency amplifier 21 and a dummy load 24, a cold cathode chip 10 'connected to the output end of the circulator 23 by a 50Ω transmission line 17, and a reference signal generator 20. Of the high frequency amplifier 25, a klystron 26 connected to the output terminal of the high frequency amplifier 25, and a circulator 27 connected to the output terminal of the klystron 26 and to which a dummy load 28 is connected. There is. Other configurations are the same as those in FIG.

The operation of the high frequency electron gun configured as described above will be described. The multiplier 30 multiplies the frequency of the reference high frequency signal generated by the reference signal generator 20 by an integer and inputs it to the phase shifter 22. The phase shifter 22 controls to shift the phase of the high frequency signal, which is an integral multiple, by a preset phase. The high frequency amplifier 21 amplifies the phase-shifted high frequency signal and supplies it to the cold cathode chip 10 'through the circulator 23 through the 50Ω transmission line 17 without loss of waveform. As a result, the micro cathode 12 and the gate electrode 1 of the cold cathode chip 10 'are
4 (FIG. 5) and a high frequency voltage is applied.

On the other hand, the high frequency amplifier 25 amplifies the reference high frequency signal generated by the reference signal generator 20 and inputs it to the klystron 26. The klystron 26 further amplifies the amplified reference high frequency signal, and supplies the high frequency high frequency electric field 41 into the first resonance cavity 2 by the waveguide 4.

The reflected wave reflected by the cold cathode chip 10 'is sent to the dummy load 24 by the circulator 23 and is prevented from returning to the high frequency amplifier 21, and the reflection reflected by the first resonance cavity 2 is prevented. The wave is sent to the dummy load 28 by the circulator 27 and is prevented from returning to the klystron 26, as in the case of FIG. 6.

FIG. 9 shows the operation of this high-frequency electron gun. FIG. 9A shows the electric field waveform in the first resonance cavity 2,
(B) shows an electric field waveform between the micro cathode 12 and the gate electrode 14 of the cold cathode chip 10 ′, and (c) shows a current waveform accelerated and emitted from the first resonant cavity 2. As shown in this figure,
Both the electric field of the first resonance cavity 2 (Fig. (A)) and the gate-emitter electric field of the cold cathode chip 10 '(Fig. (B)) are positive electric fields (electric fields in the direction of emitting and accelerating electrons). Only during this period, electrons are emitted and accelerated from the first resonance cavity 2 ((c) in the figure). Then, the electrons emitted from the first resonance cavity 2 are further accelerated in the second resonance cavity 3 and emitted from the emission port 62 as a high energy electron beam 43. The pulse width of this high energy electron beam 43 is
The phase difference between the high frequency voltage between the gate and the emitter and the high frequency electric field supplied to the first resonance cavity 2 (that is, the phase shifter 2
Under the condition that the phase shift amount by 2) is zero,
As shown in FIG. 9, it is determined by the frequency of the high-frequency voltage applied between the gate and the emitter of the cold cathode chip 10 '(that is, the multiplication order of the multiplier 30).

As described above, in this embodiment, the cold cathode chip 1 is used.
Since the pulse width of the current extracted from the cold cathode chip 10 'can be set by the frequency of the high frequency voltage applied to 0', it is possible to output an electron beam with a short pulse by increasing the multiplication order of the multiplier 30. Become.
For example, assuming that the multiplication order of the multiplier 30 is 3, as shown in FIG. 10, the cold cathode chip 10 ′ has a high frequency of 3 times the high frequency electric field of the first resonance cavity 2 ((a) in the figure).
Is given between the gate and the emitter (FIG. 2 (b)), and a shorter pulse width emission current can be obtained as shown in FIG. 2 (c). And the multiplication order is 4, 5, ...
.., the pulse width of the emission current can be further shortened.

Furthermore, if the phase shifter 22 is made variable so that the amount of phase shift can be finely adjusted, it is possible to output an electron beam having a shorter pulse width than in the case shown in FIG. 9C. Become.

[0051]

As described above, according to the present invention, a cold cathode chip having a large number of microcathodes formed on a substrate by using vacuum microelectronics is used instead of the conventional hot cathode. There is no limit of electron emission due to, and it is possible to extract and accelerate electrons to the limit of the space charge limited region by a high frequency electric field, and it is possible to obtain an electron beam of large current and low emittance.

Particularly, according to the invention described in any one of claims 2 to 5, the amount of electrons emitted from the microcathode can be controlled by the gate electrode arranged on the substrate.

According to the sixth aspect of the invention, there is a phase difference between the high frequency voltage applied between the micro cathode and the gate electrode and the high frequency electric field supplied into the resonant cavity. Since the electron beam is given, an electron beam having a pulse width corresponding to this phase difference can be obtained. Therefore, an electron beam having a shorter pulse width can be obtained by setting the phase difference to be minute.

According to the invention described in claim 7, it is possible to obtain an electron beam having a pulse width according to the multiplication order by the frequency multiplication means.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing the configuration of a high frequency electron gun according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a sectional configuration of a cold cathode chip in the high frequency electron gun of FIG.

FIG. 3 is a sectional view showing a sectional configuration of a cold cathode chip of a high frequency electron gun according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a sectional configuration of a cold cathode chip of a high frequency electron gun according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a sectional configuration of a cold cathode chip of a high frequency electron gun according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing an overall configuration of a high frequency electron gun according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram showing the overall configuration of a high frequency electron gun according to a sixth embodiment of the present invention.

FIG. 8 is a waveform diagram for explaining the operation of the high frequency electron gun of FIG.

9 is a waveform diagram for explaining the operation of the high frequency electron gun of FIG.

FIG. 10 is a waveform diagram for explaining the operation of the high frequency electron gun of FIG. 7.

FIG. 11 is a partial cross-sectional view showing the configuration of a conventional high frequency electron gun.

12 is an explanatory diagram for explaining the operation of the high frequency electron gun in FIG. 11. FIG.

[Explanation of symbols]

2 first resonance cavity, 3 second resonance cavity, 4 waveguide, 1
0,10 'cold cathode chip, 11 substrate, 12 micro cathode, 13 insulating layer, 14 gate electrode, 15 DC power supply,
16 pulse generator, 1750 Ω transmission line, 18 high frequency generator, 20 reference signal generator, 21,25 high frequency amplifier, 22 phase shifter, 23,27 circulator, 26 klystron, 30 multiplier, 41 high frequency electric field, 62 emission mouth.

Claims (7)

[Claims] 1. A high frequency electron gun having an accelerating tube for accelerating electrons, comprising: a resonance cavity formed for extracting, converging and accelerating electrons along the accelerating tube, and the resonance cavity. A cold cathode chip provided at one end of the axis body of the accelerating tube and having a substrate and a large number of microcathodes formed on the substrate; and a microcathode of the cold cathode chip in the resonance cavity. A high-frequency electron gun, comprising: a high-frequency electric field supply means for supplying a high-frequency electric field for extracting electrons from the electron gun. 2. The substrate of the cold cathode chip, further comprising:
The high frequency electron gun according to claim 1, wherein a gate electrode for controlling electrons emitted from the microcathode is arranged. 3. The high frequency electron gun according to claim 2, further comprising a DC power supply for applying a DC voltage between the micro cathode and the gate electrode. 4. The high frequency electron gun according to claim 2, further comprising a pulse voltage generation source for applying a pulse voltage between the micro cathode and the gate electrode. 5. The high frequency electron gun according to claim 2, further comprising a high frequency voltage generation source for applying a high frequency voltage between the micro cathode and the gate electrode. 6. A phase difference providing means for providing a phase difference between a high frequency voltage applied between the microcathode and the gate electrode and a high frequency electric field supplied in the resonant cavity. The high frequency electron gun according to claim 2, wherein 7. A frequency multiplication means for multiplying the frequency of the high-frequency voltage applied between the microcathode and the gate electrode to an integral multiple of the frequency of the high-frequency electric field supplied to the resonance cavity. The high frequency electron gun according to claim 2, wherein