JPH02230638A - Progressive wave deflecting electrode - Google Patents

Abstract

PURPOSE:To eliminate voltage distribution in a beam running direction, in a deflecting direction and in a lateral direction by propagation deflecting voltage, at a propagation speed almost the same as the beam running speed, from an input side end face in the beam running direction of a plate electrode to an output side end face. CONSTITUTION:When the beam of a charged particle 30 is deflected by a progressive wave magnetic field in vacuum, connecting leads 36, 38 are provided each of which has homogeneous structure in a lateral direction X that is orthogonal to a beam running direction Z and to a deflecting direction Y, and by which deflecting voltage is applied to a pair of plate electrodes 32, 34 opposed to one another being continuously formed in the beam running direction as well as to the end face in the beam running direction of the plate electrode 32. The deflecting voltage from a deflecting voltage generator 40 is propagated at a propagation speed almost the same as the beam running speed from an input side end face 32A in the beam running direction of the plate electrode 32 to an output side end face 32B. Voltage distribution in a beam running direction of a deflecting electrode, in a deflecting direction, and in a lateral direction are thus eliminated.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a traveling wave type deflection electrode for deflecting a charged particle beam in a vacuum using a traveling wave electric field, and in particular, the present invention relates to a traveling wave type deflection electrode for deflecting a charged particle beam in a vacuum using a traveling wave electric field. This invention relates to a traveling wave type deflection electrode that can apply voltage in accordance with the traveling speed of particles.

[Conventional technology]

There are various methods for deflecting charged particles using an electric field in a vacuum device, for example, an electron tube such as a streak tube or an oscilloscope. The simplest configuration is one in which two plain conductive electrodes (deflection plates) are placed facing each other. However, high frequency
Speed》When deflecting charged particles using an electric signal, the frequency characteristics of the deflection system are limited by υ1 to a band determined by the time for electrons to pass through the deflection plate (N-element transit time). In order to reduce this electron transit time effect, it is possible to shorten the deflection plate or increase the acceleration voltage to increase the electron transit speed, but this greatly reduces the deflection sensitivity and effective deflection range, making it practical for practical use. Not on point. In order to widen the frequency band without reducing the deflection sensitivity and effective deflection range, the propagation speed of the deflection voltage, which is faster than the speed of electrons, must be slowed down by providing some kind of delay structure to the deflection plate, so that the deflection voltage passes through the deflection plate. It is necessary to obtain a traveling wave deflection electric field approximately equal to the electron traveling speed. As shown in Television Vol. 18, No. 6, pages 46 to 51, one of the deflection 'R poles for obtaining this traveling wave deflection electric field is to divide the deflection plate into small pieces in the beam traveling direction, and divide them into small pieces. By connecting the divided deflection plates with a small inductance, a lumped constant deflection i! by the divided deflection plates is provided with a delay structure consisting of a constant K-type low-pass filter circuit balanced by L and C lumped constants. There are poles. Furthermore, a method in which the traveling speed (component) of the deflection voltage in the beam traveling direction is delayed by a delay line having a zigzag shape in the width direction orthogonal to the beam traveling direction and the deflection direction is disclosed in Japanese Patent Publication No. 37-13684, for example. As shown, comb-shaped electrode wires are combined with different phases,
The so-called meander type traveling wave deflection system, in which a prismatic linear electrode is bent in a zigzag shape in the width direction perpendicular to the beam travel direction and the deflection direction, and the 1-rough type traveling wave deflection system, which is an improved version of this, are available. It has been devised. Furthermore, systems in which a dielectric material is mounted on one side (non-electron beam side) of a linear electrode bent in a zigzag pattern have been devised in the meander type traveling wave deflection system and the trough type traveling wave deflection system. Furthermore, a system in which the traveling speed (component) of the deflection voltage in the beam traveling direction is delayed using a spiral delay line is disclosed in Japanese Patent Publication No. 44-1 6697, Japanese Patent Publication No. 53-26475, and Japanese Patent Publication No. 56-27984. There is. On the other hand, in a vacuum device such as a streak tube or an oscilloscope that has a charged particle deflection electrode and an output surface, the charged particles are focused on one point on the output surface by a focusing system within the vacuum device. Therefore, when a charged particle beam is deflected by applying a time-varying voltage to the deflection electrode, charged particles that are simultaneously incident on the deflection electrode must be deflected to the same position on the output surface.

[Problem to be achieved by the invention]

However, since the charged particle beam spreads due to the different initial velocities of the individual charged particles themselves, it always has a finite spread in the width direction even after passing through the deflection electrode. For a charged particle beam that spreads in the width direction, a conventional meander-type deflection electrode 10 (two overlapped in the direction perpendicular to the plane of the paper in FIG. 6), like the streak tube shown in FIG. 6, is used. , trough-type deflection electrode, spiral deflection electrode, etc.
The electrons are not uniform in the width direction perpendicular to the beam running direction and the deflection direction, but the electrons travel in the Z direction and are deflected in the Y direction (direction perpendicular to the plane of the paper in Figure 6) on the output (sweep) plane 20. If the line 10A of one bit is arranged as shown in FIG.
As we greatly ``increase the frequency'' of the temporal change of
As shown in FIG. 8, a voltage distribution is created in the X direction of the deflection electrode 10. In FIG. 6, 12 is a photocathode, 14
is a mesh acceleration ill, 16 is a focus electrode, and 18 is an anode. That is, when two temporally varying ramp voltages Vl and V2 are applied to the deflection electrode 10 as shown in FIG. 9, the electron beam is deflected in a direction perpendicular to the plane of the paper in FIG. . Here, if the temporal change in the voltage applied to the deflection electrode 10 is increased, a voltage distribution as shown in FIG. 7 will be created in the X direction of the deflection electrode 10. Incident electrons a, b that spread in the X direction
, C will be deflected by receiving different voltages, and since the amount of deflection will be different, they will be output to different positions in the Y-axis direction,
This results in blurring on the output surface 20. In reality, in the next line in Figure 7, the phase of the voltage applied to each electron a, b, and c is opposite to that in Figure 7, so the amount of blurring is considerably corrected, but the focus of the beam is As can be seen from the behavior (see FIG. 6), the distance between electrons a, b, and c becomes narrower as the output approaches 20, so it is not completely corrected and a phase shift actually occurs. Therefore, on the output 20, a sharp difference in deflection occurs between the a, b, and c@electrons, which causes the beam to become blurred. This blur in the Y-axis direction is caused by applying a high-speed voltage to the deflection electrode 10, and for example, femtosecond FRI1! In a streak tube having J resolution, this becomes a problem even in a practical range. Note that a simple deflection system consisting of only two opposing deflection plates or a split type deflection plate has a low bandwidth to begin with.
It was not possible to apply a fast deflection voltage. The present invention has been made to solve the above-mentioned conventional problems.The present invention has been made in order to solve the above-mentioned problems of the conventional art. An object of the present invention is to provide a traveling wave type deflection electrode that can apply an electric current.

[Means to achieve the task]

The present invention provides a traveling wave type deflection electrode for modifying a charged particle beam in a vacuum by a traveling wave electric field, which has a uniform configuration in the width direction perpendicular to the beam travel direction and the deflection direction, and A pair of plate-shaped electrodes facing each other are formed continuously in the beam running direction, and a connection lead for applying a deflection voltage to at least one end face of the plate-shaped electrode in the beam running direction is provided. The above object is achieved by causing the beam to propagate from the input side end face in the beam travel direction of the plate-shaped electrode to the output side end face at a propagation speed substantially equal to the beam travel speed. Further, at least one of the plate-shaped electrodes has a three-layer structure consisting of a dielectric and two electrode plates sandwiching the dielectric, and the deflection voltage is applied to the beam-side electrode plate, and the outside (lI1 The electrode plate is grounded. Also, both of the plate forest electrodes have the three-layer structure, and both have the following:
Deflection voltages of equal amplitude and opposite signs are applied to each other. Further, the connection portion between the plate-shaped electrode and the connection lead is approximately 2 mm, with the connection point of the connection lead being the apex, and the end surface of the plate-shaped electrode being the base.
It has an equilateral triangular shape. Further, the plate-shaped electrode is bent in a zigzag shape in the deflection direction.

[Action and effect]

The present invention provides a traveling wave type deflection electrode for deflecting a beam of charged particles 30 in a vacuum using a traveling wave electric field, as in the first embodiment shown in FIG.
A pair of opposing plates that have a uniform configuration in the width direction (X direction perpendicular to the paper surface) perpendicular to the deflection direction (Y direction) and the deflection direction (Y direction), and are continuously formed in the beam traveling direction. The plate-shaped electrodes 32 and 34 are provided with connection leads 36 and 38 for applying a deflection voltage to the end face of at least one of the plate-shaped electrodes (32) in the beam traveling direction, and for example, the deflection voltage generated by the deflection voltage generation 540 is , at a propagation speed substantially equal to the dome travel speed, the input side end surface 3 of the plate-like electrode 32 in the beam travel direction.
2A to the output side end face 32B. In this way, it is possible to eliminate the voltage distribution in the width direction of the deflection electrode, which is perpendicular to the direction of movement of the deflection electrode and the direction of deflection. Therefore, even if a high-velocity deflection voltage is applied to charged particles with a beam spread out, all the charged particles incident on the deflection electrode at the same time can be deflected to the same position on the output surface, and the beam can prevent blurring. Furthermore, since the velocity of the deflection voltage in the beam traveling direction and the velocity of the charged particles are substantially the same, the band can be made high.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. In the first embodiment of the present invention, as shown in FIG.
In a traveling wave type deflection electrode for deflecting charged particles 30 traveling in the Y direction by a traveling wave electric field, one of the plate electrodes includes a dielectric 50 and two plate shaped plates sandwiching the dielectric 50. The beam-side electrode plate 52 of the root-shaped electrode 32 is provided with a plate-shaped electrode 32 having a 3 m structure consisting of electrode plates 52 and 54.
From the direction in which the charged particles 30 are incident, the deflection voltage generator 40
, a deflection voltage is applied through the transmission line 56 and the connection lead 36, and the outer electrode plate 54 is connected to the transmission line 56 and 58.
The plate-shaped electrode 32 having a three-layer structure is connected to the ground line of the ground line, and has a structure similar to that of a transmission line. As the dielectric material 50, for example, LiTaOx can be used. Further, the electrode plates 52 and 54 are preferably highly conductive, and for example, copper plates can be used. Alternatively, a highly conductive material such as 8β may be directly vacuum-deposited on the dielectric 50, or Au@
A three-layer structure may be formed by vacuum deposition. The other plate-shaped electrode 34 is a normal flat plate and is grounded. In the figure, reference numeral 56 indicates that the deflection voltage generated by the deflection voltage generator 40 can be applied to the plate electrode 32 without distorting the voltage waveform.
A transmission line 58 consisting of a coaxial cable, a strip line, etc., is a transmission line for grounding the output side end face of the monopolar plate 52 via a terminating resistor 60, and the transmission line 56, A ground 58 is connected to the outer electrode plate 54. The operation of the first embodiment will be explained below. The charged particles 30 traveling in the Z direction are deflected in the Y direction by the voltage applied to the electrode plate 52 of the plate electrode 32. In this case, the electrode plate 52 through which the deflection voltage passes passes between the grounded electrode plate 54 and the opposing plate-like electrodes 34, forming a transmission line with a stripline structure as a whole. Here, since the electrode plate 52 is plate-shaped, the deflection voltage is not distributed in the X direction, but moves only in seven directions with time. The moving speed of the electric field can be adjusted to the initial moving speed of the charged particles 30 by the dielectric constant of the dielectric 50, the distance between the electrode plates 52 and 54, and the distance between the plate electrode 34 facing the electrode plate 52. Therefore, the deflection voltage advances at approximately the same speed as the charged particles 30, and the charged particles 30 that are incident on the deflection electrode at the same time and spread in the X direction are deflected by the same deflection voltage. No directional spread occurs. Moreover,
Since the deflection electrode is a traveling wave type in which the speed of the charged particles 30 matches the moving speed of the electric field, the band of the deflection electrode is wide, and a high-speed deflection voltage (high frequency voltage) can be applied to the deflection electrode. . At the output end of the electrode plate 52, a transmission line 58 is connected as well as at the input end.
and is finally terminated with a terminating resistor 60 to prevent voltage wave reflection. Note that it is also possible to omit the termination resistor 60 and leave the termination open. Next, a second embodiment of the present invention will be described in detail. In this second embodiment, as shown in FIG. 2, two deflection voltage generators 40A and 40B that generate deflection voltages are provided, with plate electrodes 32 having a three-layer structure facing each other, similar to those in the first embodiment. They are installed so close to the electrode plate 52 that there is no need to connect them with a transmission line, so that voltages of equal amplitude and opposite signs are generated. Also, the termination is done immediately after the output end of the electrode plate 52. The other points are the same as those of the first embodiment, so the explanation will be omitted. The operation of the second embodiment will be explained below. , when deflection voltages of equal amplitude and opposite signs are applied, the midpoint between the two self-directing electrodes can be regarded as a virtual ground potential.At this time, the distance between the deflection electrodes is set to the thickness of the D1 dielectric 50. If the relative permittivity of d1 is εr, then the equivalent relative permittivity ε' of the electrode plate 52 sandwiched between the virtual ground plane and the upper electrode plate 54 can be found by the following formula, ignoring end effects: εr − − (d + D - 5r /2) / (d
+D/2)・・・・・・・・・ (1) Here, the equivalent relative permittivity εr given by formula (1) is:
(Signal) electrode plate 52, virtual ground plane, (ground) electrode plate 54
It can be regarded as the relative dielectric constant of a transmission line with a slip line structure consisting of the following. Generally, the traveling speed of the electric field on the transmission line (■) is given by the following equation. V=ETT 700 pieces ・・・・・・・・・(2
) Therefore, in the transmission line of the deflection electrode, it can be considered that μ - μ0, ε - ε0・ε', so the following formula holds. ■1 μ0/ε0・εr′) − (1/Fr1− )' /-7o/5o
)= C/F ``= ・・・・・・・・・
...(3) Here, C is the speed of light. As a practical value, D-5m++, d-1mm, dielectric 50, εr-43 L! When Ta03 is used,
εr'-=31 roar, V=5.38X10Mm/sec)
bawl. This corresponds to the velocity when electrons are accelerated at 8.2 kV. Therefore, it can be seen that such a deflection electrode works effectively at a practical accelerating voltage for electron tubes such as oscilloscopes and streak tubes. As in this second embodiment, when the three-layered plate electrodes 32 are placed opposite each other and voltages of equal amplitude and opposite signs are applied to each other, the voltage required to apply the same electric field to the charged particles 30 is This embodiment has the advantage that the amplitude is only half that of the first embodiment. Next, another example of the plate-shaped electrode 32 having a three-layer structure will be described. The plate-shaped M pole 32 of the following embodiments may be used in combination with a normal plate-shaped electrode 34 as in the first embodiment, or may be used in combination with the three-layered plate-shaped electrode 34 as in the second embodiment. Two sheets can be used facing each other. As shown in FIG. 3, the plate-shaped electrode 32 according to the third embodiment of the present invention has an electrode plate 5 at the input and output ends of the electrode plate 52.
The width of the transmission line 56 connecting the deflection voltage generator 40 and the electrode plate 52 is as wide as, for example, 5 to 20 mm. In order to connect the two smoothly when the transmission line is as thin as 5 to 1 inch, the connection plate is approximately isosceles triangular with a taper of 0.5 to 20 inches on the transmission line m56 side and 5 to 20 inches on the electrode plate 52 side. 62 is used. In this third embodiment, the electrode plate 54 is arranged close to the connection plate 62 and extended by one length, and the ends of the rectangular extension plate 64 can be connected to the ground of the transmission lines 56 and 58. . As a result, the transmission lines 56 and 58 and the electrode plate 52
It is possible to eliminate the reflection of the deflection voltage due to the difference in size between the two. Next, a fourth embodiment of the present invention will be described in detail. As shown in FIG. 4, in this fourth embodiment, in a traveling wave type deflection electrode that deflects charged particles traveling in two directions in the Y direction, two electrode plates 52 and 54 are bent in a zigzag shape in the deflection direction. , both have a slow wave structure of voltage waves in the Z direction such as +Z→+Y→+Z→−Y→+2→+Y while keeping the interval constant, for example. In this fourth embodiment, it is possible to further reduce the speed of the electric field, which is determined by the dielectric constant and structure of the dielectric 50. Next, a fifth embodiment of the present invention will be described in detail. As shown in FIG. 5, this fifth embodiment is a root-like electrode with a bent structure similar to that of the fourth embodiment, but the gap in the concave portion of the outer electrode plate 54 is set to zero, and the outer surface thereof is made planar. It is. In this embodiment, since one electrode plate 54 is planar, it is easy to achieve shape accuracy. In all of the ship descriptions, the present invention was explained using a streak tube as an example, but the scope of the present invention is not limited to this, and may be applied to other electron tubes such as oscilloscopes, or general electron tubes other than electron tubes. It is obvious that the present invention can be similarly applied to a vacuum apparatus in which it is desired to deflect a charged particle beam using an electric field.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a first embodiment of a traveling wave deflection electrode according to the present invention, FIG. 2 is a sectional view showing the structure of a second embodiment of the present invention, and FIG. FIG. 4 is a perspective view showing the structure of a fourth embodiment of the present invention; FIG. 5 is a perspective view showing the structure of a fifth embodiment of the present invention. Figure 6 is a vertical cross-sectional view of a streak tube for explaining the problems of the prior art; Figure 7 is a cross-sectional view taken along line 1-2 of Figure 6; FIG. 3 is a miniature diagram showing an example of voltage applied to an electrode. 52, 54... Electrode plate, 56, 58... Transmission line, 62... Connection plate.

Claims (5)

[Claims] (1) A traveling wave deflection electrode for deflecting a charged particle beam in vacuum using a traveling wave electric field, which has a uniform configuration in the width direction orthogonal to the beam traveling direction and the deflection direction, and Continuously formed, facing 1
comprising a pair of plate-shaped electrodes and a connection lead for applying a deflection voltage to at least one end face in the beam running direction of the plate-shaped electrode, and the deflection voltage is applied to the plate-shaped electrode at a propagation speed substantially equal to the beam running speed. A traveling wave deflection electrode characterized in that the beam propagates from an input side end face in a beam running direction of the electrode to an output side end face. (2) In the traveling wave deflection electrode according to claim 1, at least one of the plate-shaped electrodes has a three-layer structure consisting of a dielectric and two electrode plates sandwiching the dielectric, and A traveling wave type deflection electrode, characterized in that the deflection voltage is applied to the side electrode plate, and the outer electrode plate is grounded. (3) In the traveling wave deflection electrode according to claim 2, both of the plate-shaped electrodes have the three-layer structure, and deflection voltages of equal amplitude and opposite signs are applied to both. Traveling wave type deflection electrode. (4) In the traveling wave deflection electrode according to claim 1, the connection portion between the plate-shaped electrode and the connection lead has a substantially isosceles 3 whose apex is the connection point of the connection lead and whose base is the end face of the plate-shaped electrode.
A traveling wave type deflection electrode characterized by having a square shape. (5) The traveling wave type deflection electrode according to claim 1, wherein the plate-shaped electrode is bent in a zigzag shape in the deflection direction.