EP2870115A1

EP2870115A1 - Device for producing an electron beam

Info

Publication number: EP2870115A1
Application number: EP13709095.7A
Authority: EP
Inventors: Vitalij Lissotschenko
Original assignee: Limo Patentverwaltung GmbH and Co KG
Current assignee: LILAS GmbH
Priority date: 2012-07-07
Filing date: 2013-03-12
Publication date: 2015-05-13
Also published as: JP2015522923A; JP6047654B2; US20150144800A1; CN104603078A; CN104603078B; US9773635B2; WO2014009028A1

Abstract

The invention relates to a device (20) for producing an electron beam (4), which comprises a hot cathode (1), a cathode electrode (2), an anode electrode (3) having an opening (6) through which an electron beam (4) produced by the device can pass, wherein during the operation of the device (20) a voltage for accelerating the electrons exiting from the hot cathode (1) is applied between the cathode electrode (2) and the anode electrode (3), and further comprising deflection means that can deflect the electron beam (4) that has passed through the opening of the anode electrode (3), wherein the deflection means comprise at least one deflection electrode (8, 12), which can reflect the electron beam (4) and/or which comprises a deflection surface (9) that is inclined towards the propagation direction of the electron beam (4).

Description

"Device for generating an electron beam"

The present invention relates to a device for generating an electron beam according to the preamble of claim 1 and an arrangement of two such devices.

Such devices are well known and can

For example, be designed as a Pierce electron gun. As deflecting means are generally used in the transverse direction of the beam two opposite electrodes, which can cause an electrostatic deflection of the electron beam. A disadvantage here it turns out that the maximum achievable deflection angle in such an electrostatic deflection in the range of about 7 °. Larger deflection angles would be desirable because it can reduce the size of a corresponding device.

Furthermore, it is desirable to have the beam profile of the

To be able to shape the electron beam with simple means.

The problem underlying the present invention is to provide a device of the type mentioned, which allows larger deflection angle and / or in the beam profile of the

Electron beam can be formed by simple means and / or works the low-maintenance and / or with a longer

or more intense line can be generated.

This is inventively achieved by a device of the type mentioned above with the characterizing features of claim 1 and / or claim 12 and / or claim 14 and / or claim 17 and / or claim 18. The

Subclaims relate to preferred embodiments of the invention. According to claim 1 it is provided that the deflection means a

Include deflection electrode, on which the electron beam can be reflected and / or has an inclined to the propagation direction of the electron beam deflection. Due to the reflection on the deflection electrode, which is a reflection on a

Mirror corresponds to very large deflection angle, for example, between 0 ° and 180 ° possible.

It can be provided that the normal on the deflection of the deflection electrode with the connecting line between the

Glow cathode and the opening in the anode electrode forms an angle between 0 ° and 90 °, preferably an angle between 20 ° and 70 °, in particular an angle between 30 ° and 60 °, for example an angle of 45 °. At an angle of 45 ° would result in a deflection angle of 90 °.

Preferably, the deflection electrode is at the same potential as the cathode electrode, in particular connected to the same voltage source as the cathode electrode. By connecting to the same voltage source can be ensured that the electrons are largely completely decelerated by the deflection.

Furthermore, it can be provided that the device comprises a further electrode which has a positive potential with respect to the deflection electrode and can accelerate the electrons after the interaction with the deflection electrode. In this way, the braked electrodes can be accelerated toward the additional electrode. This additional electrode should therefore be positioned so that the acceleration occurs at the desired deflection angle. According to claim 12 it is provided that the deflection means comprise two opposing electrodes, between which an alternating voltage is applied, through which the electron beam can be deflected so that thereby the beam profile of the electron beam can be designed specifically. The

AC voltage can have a frequency greater than 10kHz,

preferably between 25 kHz and 75 kHz, in particular between 40 kHz and 60 kHz, for example have a frequency of 50 kHz.

The two opposing electrodes can due to the relatively high frequency of the AC voltage the

Electron beam at high speed on a too

moving workpiece back and forth. In particular, the alternating voltage can be influenced in a targeted manner in order to make some areas of the surface of the workpiece longer with the

To apply electron beam as other areas. In particular, when changes are caused to the workpiece by the electron beam caused by the heat energy transmitted by the electron beam, the effective beam profile of the electron beam on the workpiece corresponds to an averaged intensity distribution of the electron beam reciprocating at high speed on the workpiece. This is especially because heat processes usually proceed more slowly than the movement of the electron beam on the workpiece. It is therefore possible to selectively select or design an effective beam profile of the electron beam by means of the two electrodes and the drive AC voltage.

According to claim 14 it is provided that the device comprises heating means which can heat the at least one deflection electrode. This proves to be particularly useful when with the Electron beam workpieces are processed so that they are partially melted so that they emit particle fumes. These particle fumes can affect the

Deflection electrodes, in particular on the output side

Deflect deflection electrode of the device. By the

Heating device is the at least one, in particular the

Output-side deflection electrode heated in such a way that the deposited on the deflection electrode particles of the workpiece are promptly evaporated again or removed again from the deflection.

The heating means, for example, a power source

include, for heating electricity through the at least one

Ablenkelektrode can flow. But there is also the

Possibility of other heating means, such as one adjacent to the at least one deflection electrode arranged

Provide radiant heating.

According to claim 17 it is provided that the device

Covering means arranged so that particle vapors from the workpiece to be machined not in the range of

Glow cathode, the cathode electrode, the anode electrode or the deflection electrode can pass.

According to claim 18 it is provided that the device is designed so that it can generate an electron beam, which divided into a single spaced apart strips

having a linear cross-section. This proves to be particularly advantageous when an arrangement according to claim 19 is created from two such devices, in which the

Devices are designed and arranged so that the strips of the first device relative to the strips of the second device so offset to each other, that in the work area a

continuous line, in which one strip of the first device alternates with a strip of the second device. In this way, longer or more intense lines can be generated.

Other features and advantages of the present invention will become more apparent from the following description

Embodiments with reference to the accompanying

Illustrations. Show in it

Fig. 1 is a schematic representation of a first

Embodiment of an inventive

Contraption;

Fig. 2 is a schematic representation in which the intensity I in a working plane of an electron beam to

different time intervals ti to t _N against

Location coordinate X is plotted;

Fig. 3 is a schematic representation corresponding to Fig. 2, which represents the time averaging of the intensity of the electron beam

4 shows a schematic partial plan view of a second

Embodiment of a device according to the invention;

Fig. 5 is a partial side view of the embodiment according to

Figure 4

Fig. 6 is a perspective view of a third

Embodiment of an inventive

Contraption;

Fig. 7 is a perspective view of a fourth

Embodiment of an inventive

Contraption;

8 is a side view of the embodiment of FIG .. 7 In the figures, the same or functionally identical parts or

Elements provided with the same reference numerals. 4 and 5 each show a Cartesian coordinate system.

In the described device some or in particular all parts may be arranged in a vacuum. That too

required housing is not or not fully shown in the figures.

The device 20 shown in Fig. 1 comprises a hot cathode 1, a cathode electrode 2 and an anode electrode 3. With regard to these parts, the device 20 is substantially equivalent to a Pierce type electron gun. It can generate an electron beam 4.

The hot cathode 1 is formed as a wire and extends into the plane of the drawing in FIG. 1 or in one

Longitudinal direction perpendicular to the propagation direction of the

Electron beam 4 is arranged. By this configuration, a line-shaped cross section of the electron beam 4 is achieved, wherein the longitudinal direction of the line-shaped cross-section parallel to

Longitudinal direction of the hot cathode 1 forming wire is aligned.

The hot cathode 1 is acted upon by voltage means, not shown, in such a way that a current flows through the hot cathode 1, which leads to a heating of the hot cathode 1. In this case, the hot cathode 1 may at least partially be at the same potential as the cathode electrode 2.

The cathode electrode comprises parts 5, which extend away from the hot cathode 1 and an angle between 70 ° and 110 °, For example, include an angle of about 90 ° with each other. The two parts 5 extend into the plane of the drawing of FIG. 1, in particular without changing their cross section.

However, there is also the possibility that the cathode electrode 2 or the parts 5 of the cathode electrode 2 in the

Longitudinal direction of the hot cathode 1 forming wire a

Have structuring that can cause a modulation of the electron beam 4 in the longitudinal direction of the line-shaped cross-section.

The anode electrode 3 has an opening 6, through which the electron beam 4 emanating from the hot cathode 1 can pass. The opening 6 is in particular rectangular and can in its longitudinal direction, which in the drawing plane of FIG

extends, have a substantially larger dimension than in their transverse direction to pass the line-shaped electron beam.

During operation of the device 20, a voltage generated by a voltage source 7 schematically indicated in FIG. 1 is present between the cathode electrode 2 and the anode electrode 3

Acceleration of emerging from the hot cathode 1 electrons. The voltage may be, for example, between 1 kV and 10 kV. In this case, the cathode electrode 2 is connected to the negative pole and the anode electrode 3 to the positive pole of the voltage source 7

connected, in particular, the anode electrode 3 is additionally connected to ground.

The device 20 furthermore comprises a deflection electrode 8 serving as deflection means, which is arranged behind the anode electrode 3 in the beam path of the electron beam 4. The electron beam 4 facing side of the deflection 8 serves as a deflection 9. This deflection surface 9 encloses an angle β with the direction of propagation of the electron beam 4, which is shown in FIG

Embodiment is approximately equal to 45 °. As a result, the angle of incidence γ between the incidence solder and the electron beam is 45 °.

The deflection electrode 8 is likewise at a negative potential, in particular at the same negative potential as the cathode electrode 2. It is preferably connected to the negative pole of the same voltage source 7 as the cathode electrode 2

Electron beam at the deflection electrode 8 come to a standstill.

The device 20 further comprises in the propagation direction of the electron beam 4 behind the deflection electrode 8 another

Electrode 10 having an opening 11 for the passage of the

Electron beam 4, which corresponds to the opening 6. The further electrode 10 is connected to ground and therefore has a positive potential with respect to the deflection electrode 8. Therefore, the electrons of the electron beam 4 braked at the deflecting electrode are accelerated by the further electrode 10 toward the further electrode 10 and pass through the opening 11.

Due to the orientation of the deflection surface 9 of the deflection electrode 8 at an angle of 45 °, the further electrode 10 to the

Deflection electrode 8 also aligned at an angle of 45 °. Overall, so that the further electrode 10 perpendicular to

Anode electrode 3 aligned. The electron beam 4 is thus deflected at the deflection surface 9 by an angle of 90 °. In particular, the deflection electrode 8 acts together with the further electrode 10 like a mirror for the electron beam 4, as in a Reflection on a mirror of the angle of incidence γ is equal to the angle of divergence δ.

The deflection surface 9 of the deflection electrode 8 may be oriented at angles other than the imaged 45 ° angle to the electron beam 4. Then, accordingly, the further electrode 10 must be aligned and positioned differently, so that the angle of incidence γ corresponds to the angle of reflection δ.

Furthermore, it is possible to make the deflection electrode 8 pivotable, so that during operation another

Direction of deflection can be selected. For example, stepper motors or piezoelectric elements can be used for this purpose. According to the pivoting of the deflection 8, the further electrode 10 would then have to be pivoted and moved.

There is also the possibility that the deflection surface 9 of the deflection electrode 8 is curved, in particular concavely curved, in order to focus the electron beam 4.

In FIG. 1, a further deflection electrode 12 is arranged behind the further electrode 10 by way of example, behind which an additional further electrode 13 having an opening 14 is provided. By the further deflection electrode 12 and the additional additional electrode 13, the electron beam 4 is deflected once again by 90 °. On the further deflection electrode 12 and the additional additional electrode 13 can also be omitted. On the other hand, more than two deflection units may also consist of one deflection electrode and another

Electrode be provided.

When the cathode electrode 2 and the parts 5 of the cathode electrode 2 in the longitudinal direction of the hot cathode 1, respectively forming a structuring to a modulation of the electron beam 4 in the longitudinal direction of the linear

To effect cross-section, it can be provided that then the anode electrode 3 and / or the deflection electrode 8, 12 and / or the further electrode 10, 13 have a corresponding structuring in the longitudinal direction of the forming the hot cathode 1 wire.

Optionally, two electrodes 15, 16 acting as a plate capacitor are provided behind the two additional electrodes 12, 13, to which an alternating voltage is applied. The corresponding

Voltage source is not shown. The alternating voltage may for example have a frequency greater than 10 kHz, preferably between 25 kHz and 75 kHz, in particular between 40 kHz and 60 kHz, for example a frequency of 50 kHz. The two additional electrodes 12, 13 can also be omitted. They merely serve to shape the beam profile of the electron beam 4, as will be explained in more detail below. When a

Beam shaping is not desired, the two additional electrodes 12, 13 omitted.

The two acting as a plate capacitor electrodes 15, 16 can because of the relatively high frequency of the AC voltage, the electron beam 4 at high speed on a workpiece to be machined (not shown) back and forth. In particular, the AC voltage can be influenced in a targeted manner in order to apply some time to the electron beam 4 to some areas of the surface of the workpiece than to other areas.

FIG. 2 shows by way of example a narrow electron beam which is moved in a position coordinate X on a workpiece which

for example, corresponds to the direction perpendicular to the longitudinal extent of the cross section of the electron beam line. It is in Fig. 2 applied to the top of the intensity of the electron beam 4.

In particular, to t _N assigned in which the electron beam 4 is incident on the area having the corresponding spatial coordinates X the individual intensity distributions of the time intervals ti.

FIG. 3 shows a schematic representation corresponding to FIG. 2, which reproduces the time-averaging of the intensity of the electron beam. In particular, when changes are to be effected on the workpiece by the electron beam 4, by those of the

Electron beam transmitted thermal energy caused corresponds to the exemplary averaged in Fig. 3 illustrated

Intensity distribution 17 the effective beam profile of

Electron beam 4 on the workpiece. This is particularly because heat processes usually proceed more slowly than the movement of the electron beam 4 on the workpiece.

So there is the possibility of using the two as

Plate capacitor acting electrodes 15, 16 and the

Ansteuerwechselspannung targeted to select or design an effective beam profile of the electron beam 4. Fig. 3 shows only an arbitrary example. Other beam profile shapes are possible.

If a very long electron beam line is to be generated, it can be provided that the wire serving as the hot cathode 1 and / or the cathode electrode 2 and / or the anode electrode 3 and / or the deflection electrodes 8, 12 and / or the further electrode 10, 13 in FIG the longitudinal direction of the wire forming the hot cathode 1 is or are divided into segments. As a result, a modular construction of the device can be made possible.

The embodiment of a device 21 depicted in FIGS. 4 and 5 differs from the first embodiment in that the second deflection electrode 12 is oriented so that the electron beam 4 is reflected from the xy plane upwards in the z direction out of the device. The electron beam 4 is indicated here only schematically by a circle, but in particular should have a line-shaped cross section. The line extends before the reflection at the second

Deflection electrode 12 in the z-direction and after the reflection at the second deflection electrode 12 in the x-direction.

The only schematically indicated second deflection electrode 12 may be more extensive in the x-direction than in the y-direction. Furthermore, the second deflection electrode 12 may be a curved, in particular concavely curved electrode. The first deflecting electrode 8, which is shown only schematically, may also be more extensive in the z direction than in the x direction because of the linear cross section of the electron beam 4. Furthermore, the first deflecting electrode 8 may also be a curved, in particular concavely curved electrode.

In the embodiment of a device 21 according to the invention shown in FIGS. 4 and 5, heating means continue to be used

intended. For this purpose, the device 21 has a power source, not shown, which is connected to the second deflection electrode 12 in such a way that a current flows through the second deflection electrode 12. This current should be sufficiently large to heat the second deflection electrode 12 to a sufficiently high temperature to prevent any build-up of particulate matter

To evaporate machined workpiece.

The illustrated in Fig. 6 third embodiment of a

Device 22 according to the invention can produce an electron beam 4 with a linear cross-section. In Fig. 6 is a part of a Housing 18 shown, from which plate-shaped cover means 19 extend to the second deflection electrode 12. These

plate-shaped covering means 19 prevent particle vapors from the workpiece to be machined in the region of the hot cathode 1, the cathode electrode 2, the anode electrode 3 or the

Pass deflection electrode 8.

At the same time as in the second embodiment

be provided that heating means for the second deflection electrode 12 are provided. Also in this third embodiment, the second deflection electrode 12 can be heated to a sufficiently high temperature to evaporate any deposits of particles of the workpiece to be machined.

The illustrated in Fig. 7 and Fig. 8 fourth embodiment of a device according to the invention substantially corresponds to the arrangement of two devices 22, 22 'in FIG

Devices 22, 22 'are arranged so that their

Electron beams 4, 4 'on the workpiece to be machined 25 overlap. This is shown in detail in FIG. 8, which shows that both devices 22, 22 'generate electron beams 4, 4' with linear or strip-shaped cross sections.

The devices 22, 22 'are designed so that in

Line longitudinal direction of the linear cross-section of

Electron beams 4, 4 'each spaced-apart strips 23, 23' are arranged. The intermediate space 24, 24 'between the strips 23, 23' is in each case as large as a strip 23, 23 '. Furthermore, the strips 23 of the first device 22 relative to the strips 23 'of the second device 22' are offset from one another such that on the workpiece 25 results in a continuous line, in each case a strip 23 of the first device 22 alternates with a strip 23 'of the second device 22'.

Claims

claims:

1. Device (20, 21, 22, 22 ') for generating a

Electron beam (4, 4 ') comprising a thermionic cathode (1), a cathode electrode (2), an anode electrode (3) having an opening (6) through which one of the device (20, 21, 22, 22') generated Electron beam (4, 4 ') can pass, wherein in

Operation of the device between the cathode electrode (2) and the anode electrode (3) a voltage for

Acceleration of the thermionic cathode (1) exiting electrons,

Deflection means passing through the opening of the

Anode electrode (3) can be deflected electron beam (4, 4 '), characterized in that the deflection means comprise at least one deflection electrode (8, 12) on which the electron beam (4, 4') can be reflected and / or the one to the

Propagation direction of the electron beam (4, 4 ') inclined deflection surface (9).

2. Device (20, 21, 22, 22 ') according to claim 1, characterized

characterized in that the normal on the deflection surface (9) of the at least one deflection electrode (8, 12) with the

Connecting line between the hot cathode (1) and the opening (6) in the at least one anode electrode (3) includes an angle (ß) between 0 ° and 90 °, preferably an angle (ß) between 20 ° and 70 °, in particular an angle (ß) between 30 ° and 60 °, for example, an angle (ß) of 45 °.

3. Device (20, 21, 22, 22 ') according to one of claims 1 or 2, characterized in that the at least one

Deflection electrode (8, 12) at the same potential as the cathode electrode (2), in particular to the same

Voltage source (7) like the cathode electrode (2)

connected.

Device (20, 21, 22, 22 ') according to any one of claims 1 to 3, characterized in that the device (20, 21, 22, 22') comprises a further electrode (10, 13) facing the at least one deflection electrode (8, 12) a positive

Has potential and the electrons can accelerate after interaction with the at least one deflection electrode (8, 12).

5. Device (20, 21, 22, 22 ') according to one of claims 1 to 4, characterized in that the deflection surface (9) of the at least one deflection electrode (8, 12) is curved, in particular concavely curved.

6. Device (20, 21, 22, 22 ') according to one of claims 1 to 5, characterized in that the hot cathode (1) is formed as a wire and extending in a longitudinal direction perpendicular to the propagation direction of the electron beam (4, 4th ')

is arranged, to obtain a line-shaped cross section of the electron beam (4, 4 '), wherein the

Longitudinal direction of the line-shaped cross section is aligned parallel to the longitudinal direction of the hot cathode (1) forming wire.

7. Device (20, 21, 22, 22 ') according to claim 6, characterized

in that the wire serving as the hot cathode (1) and / or the cathode electrode (2) and / or the

Anode electrode (3) and / or the at least one

Deflection electrode (8, 12) and / or the further electrode (10, 13) in the longitudinal direction of the hot cathode (1) forming the wire is divided into segments or are.

8. Device according to one of claims 6 or 7, characterized

in that the cathode electrode (2) and / or the anode electrode (3) and / or the at least one

Deflection electrode (8, 12) and / or the further electrode (10, 13) extending in the longitudinal direction of the hot cathode (1) forming wire without change in cross section.

9. Device (20, 21, 22, 22 ') according to one of claims 6 or 7, characterized in that the cathode electrode (2) and / or the anode electrode (3) and / or the at least one deflection electrode (8, 12) and / or the further electrode (10, 13) have in the longitudinal direction of the hot cathode (1) forming the wire at least one structuring, which can cause a modulation of the electron beam (4, 4 ') in the longitudinal direction of the line-shaped cross-section.

10. Device (20, 21, 22, 22 ') according to one of claims 1 to 9, characterized in that the deflection surface (9) of the at least one deflection electrode (8, 12) movable,

in particular tiltable.

11. Device (20, 21, 22, 22 ') according to one of claims 1 to 10, characterized in that the construction and / or the control of the hot cathode (1), the cathode electrode (2) and the anode electrode (3) of the structure and / or the

Control of a Pierce electron gun corresponds.

12. Device (20, 21, 22, 22 ') according to one of claims 1 to 11 or according to the preamble of claim 1, characterized

characterized in that the deflection means two each other

opposite electrodes (15, 16), between which an alternating voltage is applied, through which the electron beam (4, 4 ') can be deflected such that thereby the beam profile of the electron beam (4) can be designed specifically.

13. Device (20, 21, 22, 22 ') according to claim 12, characterized

characterized in that the alternating voltage has a frequency greater than 10 kHz, preferably between 25 kHz and 75 kHz, in particular between 40 kHz and 60 kHz, for example a frequency of 50 kHz.

14. Device (20, 21, 22, 22 ') according to one of claims 1 to 13 or according to the preamble of claim 1, characterized

characterized in that the device (20, 21, 22, 22 ')

Heating means which can heat the at least one deflection electrode (8, 12).

15. Device (20, 21, 22, 22 ') according to claim 14, characterized

characterized in that the output-side deflection electrode (12) can be heated by the heating means.

16. Device (20, 21, 22, 22 ') according to any one of claims 14 or 15, characterized in that the heating means a

Power source include, which can flow for heating current through the at least one deflection electrode (8, 12).

17. Device (20, 21, 22, 22 ') according to one of claims 1 to 13 or according to the preamble of claim 1, characterized

characterized in that the device (20, 21, 22, 22 ')

Covering means (19) arranged so that

Particle vapors of the workpiece to be machined (25) can not reach into the region of the hot cathode (1), the cathode electrode (2), the anode electrode (3) or the deflection electrode (8).

18. Device (20, 21, 22, 22 ') according to one of claims 1 to 13 or according to the preamble of claim 1, characterized

in that the device (20, 21, 22, 22 ') is designed such that it can produce an electron beam (4, 4') which has a line-shaped cross section which is subdivided into individual spaced-apart strips (23, 23 ').

19. arrangement of two devices (20, 21, 22, 22 ') after

Claim 18, characterized in that the devices (20, 21, 22, 22 ') are designed and arranged such that the strips (23) of the first device (22) relative to the

Strip (23 ') of the second device (22') so offset

to each other, that in the work area a

shows a continuous line in which one strip (23) of the first device (22) alternates with one strip (23 ') of the second device (22').