EP1203395B1 - Device and method for ion beam acceleration and electron beam pulse formation and amplification - Google Patents

Description

The invention relates to an apparatus and method for ion beam acceleration and electron beam pulse shaping and amplification according to the independent claims.

For ion beam acceleration of heavy ions such as carbon ions, oxygen ions and the like in linear accelerators and cyclotron accelerators, powers in the range of several megawatts are required at frequencies around 300 MHz. For such high powers and at such frequencies, the conventional high-frequency power amplifiers such as cup-circuit amplifiers, which are generally usable in a frequency range of 50 to 200 MHz and in a power spectrum up to 50 kW, fail. For higher frequencies and higher powers, the principle of Klystron power amplification, which has prevailed in the frequency range from 350 MHz to 20 GHz. As in the case of traveling-wave tubes, this is a linear arrangement in which a beam emerging from an electron gun is divided into electron packets by means of longitudinal velocity modulation. This microstructure of the beam is in so-called Buncher cavities generated by directed longitudinal high-frequency electric fields. The thus structured electron beam then generates the desired high-frequency power in the output cavity or the output circuit. After deducting this high-frequency power, its residual energy is finally dumped or discharged in a collector. Power filters with operating frequencies of 200 MHz already have a length of 5 m. For operating frequencies including the lengths are unwieldy and the devices bulky and require a space required, which is associated with considerable costs. An essential reason for this enormous space requirement lies in the formation of the electron beam pulses or the electron packets in the tube, for which elongated, several hundred centimeters long drift paths are needed. For much lower frequencies, such as below 200 MHz, the pot circuit amplifiers in the form of power tubes are therefore used, but for the frequency range between 200 and 350 MHz, there are no economic solutions that allow a high power level of several megawatts and a corresponding operating frequency.

In recent years, a concept has prevailed that is called Klystrodenprinzip. This principle is a combination of elements of the tube-driven amplifier and the klystron. The electron pulses are generated by means of a control grid and the pulsed electron beam then passes successively through an exit cavity and a collector. Although this arrangement can be made very compact, but, as far as this concept has prevailed, it is used for television stations with a relatively low transmission power of up to 60 kW in the UHF band, so that this solution can be used in competition with the standard Topfkreisverstärkern however, does not provide the high performance required for ion beam acceleration.

The Klystroden principle is from the patent EP-A-587481 (THOMSON TUBES ELEKTRONICS), March 5, 1994, from the U.S. Patent US Pat. No. 5,497,053 (SWYDEN THOMAS ET AL) March 5, 1996 from Patent Abstract PATENT ABSTRACTS OF JAPAN March 11, 1983, from DATABASE WPI Section El, Week 198135, Derwent Publications Ltd, London GB Class V05, AN 1981-j1141D XP002185134 & SU 777 754 A (RYAZA WIRELESS ING INST), January 4, 1980 and from the document LORING C JR ET AL 2 The Clysterode, a new high power electron tube for UHF industrial application 'JOURNAL OF MICROWAVE POWER AND ELECTROMAGNETIC ENERGY', 1993 USA, BD 28 No. 3, pages 174-182 XP 001039895), known.

However, power strikes capable of delivering several megawatts of gain will lose their otherwise available advantages at frequencies from 100 MHz to 400 MHz due to the technical complexity and especially the size at these low frequencies. On the other hand, Klystroden, as mentioned above, due to the use of a control grid with respect to the maximum achievable high-frequency power and with respect to the achievable maintenance intervals are extremely limited use. Power tubes such as the cup circuit amplifiers remain in the considered frequency range well below 1 MW output power in continuous operation, and pulsed operation, the maximum power falls from about 3 MW in the lower frequency range to less than 1 MW in the upper frequency range, so that they can not be used for several megawatts , The overall efficiency of these power tubes is also reduced by the requirement that the cathode heating power of typically 10 kW be continuously applied at the required pulse repetition rates for amplifying ion beam pulses of several hertz up to 50 Hz.

The object of the invention is therefore to provide a high-performance high-frequency amplifier in the frequency range from 100 MHz to about 400 MHz, which reaches in pulsed operation with a 1 ms pulse length and a repetition rate of less than or equal to 50 Hz transmitter powers up to 10 MW. Moreover, it is an object of the invention to provide a technical solution that overcomes the current critical situation in the production of high-frequency power tubes, which is that fewer and fewer providers produce such power tubes, so that in addition to the above limitations of this type of amplifier and the supply situation long term not secured appears.

This object is achieved with the independent claims, advantageous developments of the invention will become apparent from the dependent claims.

According to the invention, there is provided an electron beam pulse shaping and amplification apparatus comprising an electron gun, a high frequency deflector, a DC deflector, a counter field collector, a post accelerator, a power coupler for coupling the power of the electron beam to a load and a main collector for receiving the residual power of the electron beam , For this purpose, the devices listed above are arranged one after the other in the direction of the electron beam.

The electron beam gun initially generates a continuous electron beam which is deflected in the high-frequency deflector excited by a high-frequency excitation signal, so that only in the region of the zero crossings of this signal, the electron beam can be passed periodically in the ion beam axis. The adjoining DC deflector amplifies this effect and the portion of the deflected electron beam is collected in a collector with opposing field and this current is fed back to the cathode of the electron gun. The electron beam, which is thus divided into electron packets, is accelerated in a post-accelerator and fed to a power coupler, which can couple the power of the electron beam to a load. The remaining non-decoupled residual power of the electron beam is fed to a main collector. Thus, advantageously, instead of the longitudinal velocity modulation used in the klystron in the present invention, transverse high frequency electric fields in the high frequency deflector and transversely directed static electric fields used in the DC deflector to shape and pre-amplify electron pulses.

Thus, within a high frequency period, about 80% of the continuously delivered electron beam is deflected and trapped in a negative biased collector with reverse voltage. The continuing on the beam axis remaining electron beam pulses in the form of electron packets then pass through the main acceleration of several hundred kilovolts and reach so accelerates the output cavity of the power coupler, which couples the power of the electron beam to a consumer. The undocked residual power is collected in the main collector. The pure electron beam pulse shaping can be accommodated in this concept in a frequency range between 100 and 400 MHz within a length of only 0.5 m. This is an improvement by reducing the length by more than tenfold, especially since a Klystron for 350 MHz at the required power consumption is already 5 m long. Thus, there is no significant impediment to using the klystron for low frequencies. In the solution according to the invention, the efficiency of the klystron for the generation of high-frequency power is achieved on a much shorter length.

In a preferred embodiment of the invention, the consumer is an antenna of a coaxial cable end, which projects into a resonator, which is coupled to the electron beam via an annular gap surrounding the electron beam. This embodiment extracts with its antenna a substantial portion of the resonant energy from the resonator, and thus the electrons are braked in the electron beam, so that only a small remaining non-decoupled residual power must be collected in the main collector.

In a further preferred embodiment of the invention, the consumer is an antenna coupler of a waveguide, which is designed as a coaxial feedthrough through the wall of the resonator chamber. For this purpose, the antenna coupler protrudes into the resonator chamber, which surrounds the electron beam with an annular gap, so that energy from the electron beam can be coupled into the resonator and is then conducted away via the antenna coupler feedthrough to the waveguide.

In a further preferred embodiment of the invention, the consumer is a coupling window to a waveguide, the coupling window opening towards the resonator. Also in this embodiment, the electron beam is surrounded by the resonator with an annular gap.

Another solution according to the invention is an ion beam acceleration apparatus comprising an ion accelerator tank having a central tank axis for guiding and accelerating a pulsed ion beam of heavy ions in the tank axis. This device further comprises an electron beam pulse shaping and amplifying device with electron beam axis for microstructuring and amplifying current pulses for the supply of the device for ion beam acceleration with high frequency power.

This solution is characterized in that the Elektronenstrahlimpulsformungs- and -verstärkungseinrichtung is arranged with its electron beam axis transversely and offset from the container axis and outside of the Ionenbeschleunigertanks an electron gun, a Hochfrequenzdeflektor, a Gleichspannungsdeflektor, an opposing collector and a Nachbeschleuniger, while within the Ionenbeschleunigertanks the Device a power coupler for coupling the power of the electron beam to a consumer and a Main collector for receiving the residual power of the electron beam has. The listed device components of the Elektronenstrahlimpulsformungs- and -verstärkungseinrichtung are arranged one behind the other in the direction of the electron beam.

This solution has the advantage that the ion accelerator tank itself is simultaneously used as the output circuit for the power amplification stage. A power transfer from the amplifier to the tank is eliminated. A coupling of the power level to the tank volume is thus possible. Thus, a structure for ion beam acceleration for ion beams for heavy ions is achieved, which can be produced extremely manageable and extremely inexpensive.

For coupling between the driving electron beam and the ion accelerator tank, a spot suitable for potential is inserted along the drift tube holder of the ion beam. A transverse alternating electric field with a suitable time structure deflects electrons which are unfavorable in terms of time immediately after the pre-acceleration of the electron beam, so that only electron pulses having the desired frequency for amplifying the ion beam pulses undergo the main acceleration and are then decelerated in the field of the ion accelerator tanks because their energy is applied to the Ion beam is coupled.

Thus, in a preferred embodiment of the invention, the load is directly the pulsed ion beam.

In a further preferred embodiment of the invention, the power coupler has a resonator with an upper annular gap surrounding the electron beam radially and a lower annular gap radially surrounding the electron beam in the ion accelerator tank on. Passing through the electron beam from two annular gaps, namely an upper and a lower annular gap in the tank, appears advantageous since the electron beam must reach the cooled hanger to release its residual energy in the main collector. For this purpose, the drift distance between the gaps is advantageously kept as short as possible in order to achieve a favorable geometry, which does not significantly affect the stress distribution over the drift tube foot. In addition, advantageously, the electrons, regardless of their phase position in the pulse when passing through the two annular gaps, the same energy to the ion beam, so that the residual energy in the main collector or collector is less than 10% of the pulse energy.

To place such matched annular gaps in the ion accelerator tank, the power coupler further includes a coupling step between the annular gaps that coaxially surrounds the electron beam and is radially offset and disposed transversely to the ion beam within the ion accelerator tank, the coupling stage being attached to a drift tube mount of the ion beam.

In a further preferred embodiment of the invention, the electron beam gun is a Piercetyp electron beam gun. With such a cannon, a high-permeant electron beam with correspondingly high space charge constant according to the Child Langmuir equation is advantageously generated at pulse lengths of 1 ms, which achieves a beam current of, for example, 40 A at an acceleration voltage of 40 kV.

In a further preferred embodiment, the high-frequency deflector has a homogeneous transversely directed alternating field, with the short electron beam packets in the area The operating frequency of 100 to 400 MHz are created while the electron beam is deflected in the pulse intervals and is supplied to a collector with opposing field, which in turn provides the current of the cathode of the electron beam gun.

In a further preferred embodiment of the invention, the DC deflector has an inhomogeneous, time constant transverse electric field, while the electron beam is transversely stabilized simultaneously by means of a longitudinal magnetic field, so that the Brillouin equilibrium condition remains satisfied.

In a further preferred embodiment, the power coupler has in its output circuit a resonator which communicates with the electron beam via an annular gap. The resonator, in turn, the energy through a consumer, which is coupled via a coaxial line, a waveguide or directly, as in the case of the ion beam, be withdrawn, so that the electron packets are decelerated in the electron beam and only with low energy, which is partially below 10 % of the total electron beam energy is to be collected in the main collector.

In addition to the solution found for direct coupling to an ion beam consumer, the output circuit also has a single-column annular cavity as the resonator, the cavity surrounding the ion beam. With this solution, it is possible to connect any consumer via coaxial cable or waveguide to the power amplifying device according to the invention.

The pulse length and the repetition rate of the electron beam, the so-called macrostructure, are in the case of the invention Solution freely selectable, so that pulse lengths of one millisecond at repetition frequencies of less than 50 Hz and a power of 10 MW can be realized with the inventive device and the method according to the invention.

• Erzeugen eines Elektronenstrahls mittels einer Elektronenstrahlkanone;
• Beaufschlagen des Elektronenstrahls mit einem transversalen hochfrequenten Wechselfeld unter gleichzeitig hochfrequenter Auslenkung des Elektronenstrahls;
• Hochfrequentes Ausblenden von bis zu 80 % der Elektronenstrahlenergie zu einem Kollektor mit Gegenfeld mittels eines Hochfrequenzdeflektors und eines Gleichspannungsdeflektors;
• Nachbeschleunigen des hochfrequenzmodulierten Elektronenstrahls zu verstärkten Elektronenstrahlimpulsen;
• Auskoppeln der Hochfrequenzenergie über einen Leistungskoppler.

Since a narrow-band RF resonator, as indicated in the preferred embodiments of the invention as an annular cavity with annular gap, can only be effectively excited with an electron beam when the beam has an intensity modulation at the corresponding operating frequency, this so-called microstructure of the electron beam generated by the method according to the invention. This method according to the invention for electron beam pulse shaping and amplification has the following method steps:

• Generating an electron beam by means of an electron beam gun;
• Impinging the electron beam with a transverse high-frequency alternating field with simultaneous high-frequency deflection of the electron beam;
• Radiofrequency masking of up to 80% of the electron beam energy to a counter field collector by means of a high frequency deflector and a DC deflector;
• Post accelerating the high frequency modulated electron beam to amplified electron beam pulses;
• Decoupling the high-frequency energy via a power coupler.

Thus, the beam first passes through a homogeneous transversely directed alternating electric field, then an inhomogeneous time constant transverse electric field. In this case, about 80% of the electron beam is deflected by the beam axis and collected at a nearly constant electron energy of 40 keV in a prestressed collector with eg U = -40 kV + x. The energy of these electrons can largely be returned to the cathode of the electron gun and serves as a charging current.

The undeflected beam portion, which is present in particles or electron packets at a time interval according to the operating frequency, moves along the beam axis and passes through the main acceleration voltage, which may be for example at 300 kV, and then enters the output circuit of the resonator. Such a resonator may have a single-column annular cavity, as is common in other solutions. Such a resonator is excited by the passing electron packets, and the high-frequency fields generated in the resonator brake the electrons and simultaneously feed the output line of the amplifier, which may preferably be a coaxial line or a waveguide with corresponding coupling antennas or a corresponding coupling window. Finally, the remaining electron energy is delivered in the main collector, wherein in particular the formation according to the invention of the electron beam microstructure for a shortening of the length of otherwise usual for higher operating frequencies Klystronleistungsverstärkern provides.

Thus, in a preferred embodiment of the method, the radio frequency energy is decoupled via a coaxial cable which projects with an antenna into a ring resonator space which communicates with the high-frequency, high-energy electron beam via an annular gap surrounding the electron beam.

In a further preferred embodiment of the method, the decoupling of the high-frequency energy over a Waveguide reaches, which protrudes with a coupling antenna in a Ringresonatorraum, which communicates via a surrounding the electron beam annular gap with the high-frequency, high-energy electron beam.

In a further preferred implementation example of the method, the decoupling of the high-frequency energy via a waveguide is effected, which is connected via a coupling window to a ring resonator, wherein the ring resonator communicates with the electron beam via an annular gap surrounding the electron beam.

Another preferred embodiment of the method provides that a high space charge constant electron beam according to the Child Langmuir equation is obtained from an electron beam gun having a beam current of 20 A to 60 A, preferably between 30 to 50 A, at an acceleration voltage (U _c ) of 20 kV to 60 kV, preferably from 30 kV to 50 kV is generated.

A further preferred embodiment of the method provides that the electron beam is stabilized transversally in the Brillouin equilibrium by means of a longitudinal magnetic field. It is further provided that the intensity-modulated electron beam excites a narrow-band high-frequency resonator in the output circuit at an operating frequency. For this purpose, the electron beam passes through a homogeneous transversely directed alternating electric field, wherein between 50 and 80% of the electron beam energy are deflected by the beam axis.

In a further preferred embodiment of the method is at approximately constant electron energy of 30 keV to 60 keV in a biased collector with opposing field from -30 kV to -40 kV the deflected portion of the electron beam is collected. In this case, the energy of the collected electrons is collected in the collector with opposing field and fed as a charging current of the cathode of the electron gun.

In a further preferred implementation example of the method, the undeflected electron packets are moved and guided at a time interval of an operating frequency along the beam axis and enter a output circuit of the device, which is designed as a resonator, with a main acceleration voltage between 200 kV and 400 kV. In this case, the resonator jumps in the output circuit of the device, with high-frequency fields in the resonator receive the energy of the electrons, these decelerate and feed an output line, preferably a coaxial cable and / or a waveguide.

The remaining residual energy of the electrons is preferably released in a main collector. For electrical beam deflection in the high-frequency deflector, in a preferred embodiment of the method for an operating frequency f, the driving radio-frequency signal is set from a main component at a frequency of f / 2 and a superposition at the frequency 5f / 2 in an amplitude ratio of 5: 1. In this case, the operating frequency between 100 and 400 MHz and per period about 20% of the electron beam particles are passed in pulses, since the overlapping of the two frequencies, a corresponding zero crossing for a corresponding period of time per period is achieved.

• Fig. 1 zeigt eine Prinzipskizze einer ersten Ausführungsform einer Vorrichtung zur Elektronenstrahlimpulsformung und -verstärkung.
• Fig. 2 zeigt ein Diagramm einer Periode eines Hochfrequenzspannungssignals, das an einem Hochfrequenzdeflektor angelegt wird.
• Fig. 3 zeigt die Ablenkwirkung auf Elektronen in einem Hochfrequenzdeflektor.
• Figuren 4a und 4b zeigen Prinzipskizzen möglicher elektrischer Felder in einem Gleichspannungsdeflektor.
• Fig. 5 zeigt einen Querschnitt durch einen asymmetrischen Gleichspannungsdeflektor mit eingezeichneten Äquipotentiallinien.
• Fig. 6 zeigt mehrere Intensitätsprofile entlang der Elektronenstrahlachse für unterschiedliche Blendenöffnungen des Kollektors mit Gegenfeld.
• Fig. 7 zeigt eine Skizze der Elektronendichteverteilung nach Durchlaufen des Hochfrequenzdetektors.
• Fig. 8 zeigt eine Skizze der Elektronendichteverteilung nach Durchlaufen des Hochfrequenzdeflektors und des Gleichspannungsdeflektors.
• Fig. 9 zeigt eine Prinzipskizze einer Vorrichtung zur Elektronenstrahlimpulsformung und -verstärkung.
• Fig. 10 zeigt eine Prinzipskizze einer Vorrichtung zur Ionenstrahlbeschleunigung.

The invention will now be explained in more detail with reference to figures.

• Fig. 1 shows a schematic diagram of a first embodiment of an apparatus for electron beam pulse shaping and amplification.
• Fig. 2 FIG. 12 is a diagram showing a period of a high frequency voltage signal applied to a high frequency deflector. FIG.
• Fig. 3 shows the deflection effect on electrons in a high frequency deflector.
• FIGS. 4a and 4b show schematic diagrams of possible electric fields in a DC voltage deflector.
• Fig. 5 shows a cross section through an asymmetrical DC deflector with drawn equipotential lines.
• Fig. 6 shows several intensity profiles along the electron beam axis for different apertures of the collector with opposing field.
• Fig. 7 shows a sketch of the electron density distribution after passing through the high frequency detector.
• Fig. 8 shows a sketch of the electron density distribution after passing through the high-frequency deflector and the DC deflector.
• Fig. 9 shows a schematic diagram of an apparatus for electron beam pulse shaping and amplification.
• Fig. 10 shows a schematic diagram of an apparatus for ion beam acceleration.

Fig. 1 shows a schematic diagram of a first embodiment of an apparatus for electron beam pulse shaping and amplification. This consists essentially of a vacuum-tight Housing 28, in the cascaded an electron gun 6, a Hochfrequenzdeflektor 7, a DC deflector 8, a collector with opposing field 9 and a Nachzeleuniger not shown, the reference numeral 10 in Fig. 9 is shown housed. In the Fig. 1 The schematic diagram shown serves essentially to explain the functional principle of the transverse deflection unit for microstructuring the electron beam. The corresponding many particle calculations for forming electron packets in this device were performed by means of suitable software program packages.

The in Fig. 1 The section shown from the electron gun 6 to the collector with opposing field 9, which captures the deflected electrons shown hatched in the beam cross section shown in the x / z plane, contains the essential parts of the electron beam shaping device according to the invention. The two deflection systems 7 and 8 arranged directly behind one another can be clearly seen, wherein the second electrostatic deflection unit 8 can be supplied by the cathode potential U _c . The electric field direction E _y , which is arranged perpendicular to the plane of representation, must be oriented inversely for x> 0 than for x <0 in order to further increase the electron deflection of the upstream high-frequency deflection unit. The environment of the z-axis, as illustrated in the illustration, is kept almost field-free in the direct-voltage deflector 8 by overlapping the electrodes lying on ground in order to disturb the passing electron packets as little as possible.

Fig. 2 FIG. 12 is a diagram showing a period of a high frequency voltage signal applied to the high frequency deflector 7. FIG. For this purpose, the time in nanosecond units is entered on the abscissa and the high-frequency deflection voltage is plotted on the ordinate kV. Within a high-frequency period at an operating frequency f is given by corresponding excitation frequencies of the Hochfrequenzdeflektors 7 a recurring plateau 51 at the voltage 0 V. This recurring plateau 51 at the voltage 0 V defines the passing beam portion, which is not deflected. Furthermore, the diagram of the Fig. 2 the steeply rising voltage edges 53 and 54 at the beginning and at the end of the plateau 51, causing a strong deflection of the electron beam, which in turn defines the pulse pauses. The plateau itself corresponds approximately to a beam component of 20% or a phase width of 70 ° in units of the operating frequency. Accordingly, the driving RF signal consists of a main component at the frequency f / 2 and a superposition with the frequency 5f / 2. At an amplitude ratio of about 5: 1 and the corresponding phase relationship, this arises in Fig. 2 shown and desired waveform, which is composed of the components V = sin (πft) - 0.2 V · sin (5πft).

Fig. 3 shows the deflection effect on the electrons in a Hochfrequenzdeflektor 7. Here, the electrons in the x / y plane under the influence of the electric and magnetic field describe the tracks shown there. The advantage of crossed electrical and magnetic fields is that the deflection by means of the ExB drift essentially takes place in the x / y plane, so that the deflector plates of the high-frequency deflector 7 represent no limitation as long as the gyroradius rg is suitably selected.

The FIGS. 4a and 4b show schematic diagrams of possible electric fields in a DC voltage deflector 8. In the embodiment discussed here, the asymmetrical Gleichspannungsdeflektor the Fig. 4b in a slightly modified form as the Fig. 5 shows, applied. The unbalanced Gleichspannungsdeflektor 8 has compared to the symmetrical DC deflector of Fig. 4a the advantage of a simpler design by only four baffles 36 to 38 against six baffles 30 to 35 of the Fig. 4a ,

Fig. 5 shows a cross section through an asymmetrical DC deflector 8 with drawn equipotential lines 29. It can be clearly seen from this illustration that the center between the baffles 40 to 43 is kept free of field, so that electrons that fly through these cover plates in the center, not or only slightly in addition to get distracted. Furthermore, the modification according to the embodiment Fig. 5 compared to the schematic diagram 4b in that the baffles 41 and 42 lying at ground (0 V) are initially parallel and then partially angled with respect to the center line 44 and the baffles subjected to a negative voltage of -40 kV in this embodiment are completely angled away from the center line 44.

Fig. 6 shows several intensity profiles along the electron beam axis in the z direction for different apertures of a collector 9 with opposing field. In this representation, the z-direction is entered in centimeters on the abscissa, and the electron beam density is comparatively plotted in arbitrary units on the ordinate. The curves were recorded for three different apertures of the collector 9 with opposing fields of ≤ 5 mm, ≤ 6 mm and ≤ 7 mm. The pulse packet or electron packet periodically outputted through this shutter has a length of not quite 10 cm, the length increasing slightly with increasing diameter of the opening in the counter field collector 9. However, the intensity maximum does not depend on the aperture in this pulse width, but the intensity maximum is evident by the Gleichspannungsdeflektor with an acceleration voltage U _c determines and is equally intense at constant DC voltage.

Fig. 7 shows a sketch of the distribution of the electron density after passing through the high-frequency deflector. In this representation, the abscissa represents the x-position in mm and the ordinate the electron density in arbitrary units. After passing through the Hochfrequenzdeflektors 7 are still 37% of the electrodes in the central pass band of electron beam forming device, while large portions of the electron beam are deflected downward or upward by the high-frequency alternating field and are not available for further acceleration. The DC electron beam, as it comes from the electron gun 6, is therefore already cut into electron packets. Even more clearly shows this the Fig. 8 ,

Fig. 8 shows a sketch of the electron density distribution after passing through the high-frequency deflector 7 and the Gleichspannungsdeflektors 8. On the abscissa again the x-position in mm is entered, and on the ordinate the electron density in any comparative units. After the DC deflector, the maxima of the deflected electrodes are concentrated at a significant distance from the center of the beam, which is 0.0 mm. Only 20% of the electrons remain in the center of the beam and can be further accelerated in the following high accelerator. These 20% result from electron packets or electron pulses, as in spatial extension in Fig. 6 were presented. The cross section of the particle packages to be transported results in its density distribution to about 13 mm in the x-direction and about 11 mm in the y-direction. From this cross section, the aperture of the collector with opposing field cuts out a corresponding electron pulse beam.

Fig. 9 shows a schematic diagram of an apparatus for electron beam pulse shaping and amplification. In Fig. 9 Like reference numerals define like device components as in FIG Fig. 1 , A discussion of these device components is therefore largely omitted. In Fig. 9 is in addition to the in Fig. 1 shown device components to see a frequency converter f ₁ , which oscillates at half the operating frequency f and is supplied via a phase shifter 45 to an amplifier 48, which amplifies the signal of the frequency converter f ₁ to about 50 kW. This signal is superimposed on a signal which is supplied by a second frequency converter f ₂ , which generates a frequency of 5f / 2 and superimposes this signal on the signal of the first frequency converter at the crosspoint 50. In this case, an amplitude adjustment is set by the amplifier 49 in addition to the correct phase, so that the amplitude of the signal of the frequency converter f _{2 is} only 1/5 of the amplitude of the frequency converter f ₁ . This signal, which for a period takes the form of in Fig. 2 is applied to the plates of the high-frequency deflector 7. Superimposed on the signal is a magnetic field which is generated by the coil 47 within the housing 28.

Between the plates, an electron beam 14 is generated in the electron beam axis 5 from an electron beam gun 6, which in this embodiment is a Pierce type electron gun. This electron gun produces a high-energy electron beam with high space charge constant according to the Child Langmuir equation and is transversely stabilized by means of a longitudinal magnetic field of the coil 47 and kept in Brillouin equilibrium.

After the denomination of the electron beam in the high frequency deflector 7, both the deflected electron packets become as well as remaining in the axis center electron packets passed through the DC voltage deflector 8. The time interval of the packets is determined by the operating frequency f, which is between 100 and 400 MHz. While the deflected electron beam packet portions are received by the collector 9 with opposing field and supplied via a connecting line of the cathode of the electron beam gun 6, located in the center about 20% of the electron of the electron beam reach the post-accelerator 10, which with an acceleration voltage in this embodiment of 300 kV Electron beam pulses or electron packets energetically amplified so that they can interact with the subsequent annular resonator 15 through the annular gap 25 in interaction.

In this case, the resonator, excited by the frequency of the electron beam, withdraws energy from the electron packets, which in this embodiment is fed via an antenna 23 to a coaxial output line 12. This coaxial cable can be connected to a consumer. In other embodiments of the invention, the load is directly an ion beam of an accelerating chamber or an ion accelerator tank, for example an ion beam therapy system or an ion beam material inspection system, which is operated substantially with heavy ions such as carbon and oxygen ions.

The output line 12 may also be a waveguide which communicates with the resonator 15 via a coupling window or is connected to the resonator 15 via a coaxial feedthrough. The energy not withdrawn from the resonator 15 and thus from the electron beam 14 through the output line is absorbed by the main collector 13. This main collector 13 preferably has water-cooled walls in order to dissipate the residual energy, which in this embodiment is less than 10%. lies. At a maximum power of 10 MW, however, a high cooling capacity is required to prevent melting of the housing of the main collector.

Fig. 10 shows a schematic diagram of an apparatus for ion beam acceleration. The principle of the invention has the advantage that it can be introduced directly into a system for ion beam acceleration. Accordingly, the shows Fig. 10 an apparatus 51 for ion beam acceleration, which has an ion accelerator tank 1 with a central container axis 2 for guiding and accelerating a pulsed ion beam 3 in the container axis 2. For this purpose, a Elektronenstrahlimpulsformungs- and -verstärkungseinrichtung 4 with electron beam axis 5 for microstructuring and amplification of current pulses for the supply of the device 51 for ion beam acceleration with high frequency power is arranged such that the electron beam pulse forming and amplifying device 4 with its electron beam axis 5 arranged transversely to the container axis 2 and and outside of the ion accelerator tank 1 has an electron beam gun 6, a Hochfrequenzdeflektor 7, a DC deflector 8, an opposing collector 9 and a Nachbeschleuniger 10 and within the Ionenbeschleunigertanks 1 a power coupler 11 for coupling the power of the electron beam 14 to a consumer 12, the In this case, the pulsed ion beam 3, wherein a main collector 13, the residual power of the electron beam 14 receives and said device components successively in the direction of I. onenstrahls 14 are arranged.

For decoupling the energy of the electron beam 14 from the Elektronenstrahlimpulsformungs- and -verstärkungseinrichtung 4 are an upper annular gap 16 and a lower annular gap 17 with interposed therebetween the ion beam coaxially surrounding Coupling stage arranged. The coupling stage 18 is held by the drift tube holder 19 which simultaneously surrounds the ion beam 3 in the region of the center of the ion accelerator tank 1. The gap size and the gap distance as well as the offset distance between the electron beam axis and the ion beam axis are matched to one another such that the volume of the ion accelerator tank 1 can serve as a resonator for the pulsed electron beam, the resonator acting directly on the pulsed ion beam guided in the center.

Half the operating frequency f of the ion beam 3 is supplied in the frequency converter f ₁ via a phase shifter 45 and an amplifier 48 to a crosspoint 50, at the same time the f5 / 2 operating frequency f with the frequency converter f ₂ via the amplifier 49 is applied. With these superposed frequencies of the high-frequency deflector 7 is operated, which modulates the ion beam from the electron beam gun 6.

Subsequently, in a DC deflector 8, the deflection and the separation between deflected ion beam sections and thus pulse intervals and in the center continued ion beam sections and thus pulse lengths amplified, so that the deflected ion beam sections can be picked up by the collector 9 with the opposing field. The electron packets, which are continued centrally on the ion beam axis 5, are brought to a correspondingly high energy in the post-accelerator 10, so that they can resonate with the volume of space of the ion accelerator tank 1. In this case, a substantial part of the electron beam energy is transferred to the ion beam pulses, while a small residual amount of less than 10% of the electron beam energy is supplied to the main collector 13. In contrast to Fig. 9 this solution according to the invention has an upper annular gap 16 and a lower annular gap 17, the Surround the electron beam while a coupling piece 18 is disposed therebetween.

LIST OF REFERENCE NUMBERS

1

Ion accelerator tank

2

Central container

3

pulsed ion beam

4

Electron beam pulse shaping and amplifying device

5

electron beam axis

6

electron gun

7

Hochfrequenzdeflektor

8th

Gleichspannungsdeflektor

9

Collector with opposing field

10

post-accelerator

11

power coupler

12

consumer

13

main collector

14

electron beam

15

resonator

16

Upper annular gap

17

lower annular gap

18

coupling stage

19

Inhomogeneous field

20

Homogeneous transversally directed alternating field

21

output circuit

22

annular cavity

23

antenna

24

coaxial

25

annular gap

26

single column cavity

27

Ring resonator chamber

28

casing

29

equipotential

30-35

Baffles of the symmetrical DC deflector

36-39

Baffles of the asymmetric DC deflector

40-43

Baffles of the DC deflector

44

center line

45

phase shifter

47

Kitchen sink

48

amplifier

49

amplifier

f ₁

frequency converter

f ₂

frequency converter

50

crosspoint

51

Apparatus for ion beam acceleration

52

plateau

53-54

flanks

Claims (33)

1. Apparatus for forming and amplifying electron beam pulses, comprising

   (a) an electron gun (6),

   (b) a high frequency deflector (7),

   (c) a direct voltage deflector (8),

   (d) a collector with opposing field (9),

   (e) an after-accelerator (10),

   (f) a power coupling (11) for coupling the power of the electron beam (14) to a consumer load (12), and

   (g) a main collector (13) for receiving the remaining power of the electron beam (14),

   wherein the components (a) to (g) of the apparatus are arranged in succession in the direction of the electron beam (14).
2. Apparatus according to claim 1, characterized in that the consumer load (12) is an antenna (23) of a coax cable head (24) extending into a resonator (15) which is coupled to the electron beam (14) by an annular gap (25) surrounding the electron beam (14).
3. Apparatus according to claim 1, characterized in that the consumer load (12) is an antenna coupling of a hollow conductor, wherein the antenna coupling extends into a resonator (15) which surrounds the electron beam (14) with an annular gap (25).
4. Apparatus according to claim 1, characterized in that the consumer load (12) is a coupling window to a hollow conductor, wherein the coupling window opens to a resonator (15), which surrounds the electron beam (14) with an annular gap (25).
5. Apparatus according to one of the claims 1 to 4, characterized in that the electron beam gun (6) is an electron beam gun of the Pierce type.
6. Apparatus according to one of the claims 1 to 5, characterized in that the high frequency deflector (7) comprises a homogeneous transversally aligned alternating field (20).
7. Apparatus according to one of the claims 1 to 6, characterized in that the direct voltage deflector (8) comprises an inhomogeneous transversal electric field (19) being constant in time.
8. Apparatus according to one of the claims 1 to 7, characterized in that the power coupling (11) comprises a resonator (15) in its output circuit (21).
9. Apparatus according to claim 8, characterized in that the output circuit (21) comprises a single-gap ringlike cavity (26) as a resonator (15).
10. Apparatus for accelerating ion beams, comprising:

    (A) an ion accelerator tank (1) with central recipient axis (2) for guiding and accelerating a pulsed ion beam (3) in the recipient axis (2),

    (B) a device (4) for forming and amplifying electron beam pulses according to one of the claims 1, 5 to 9 with electron beam axis (5) for microstructuring and amplifying of current pulses for the supply of the apparatus for accelerating ion beams with high frequency power, wherein

    the device (4) for forming and amplifying electron beam pulses is arranged with its electron beam axis (5) transverse and shifted to the recipient axis (2) and comprises outside of the ion accelerator tank (1)

    (a) an electron gun (6),

    (b) a high frequency deflector (7),

    (c) a direct voltage deflector (8),

    (d) a collector with opposing field (9) and

    (e) an after-accelerator (10)
    and comprises in the ion accelerator tank

    (f) a power coupling (11) for coupling the power of the electron beam (14) to a consumer load (12),

    (g) a main collector (13) for receiving the remaining power of the electron beam (14),

    wherein the consumer load (12) is the pulsed ion beam (3).
11. Apparatus according to claim 10, characterized in that the power coupling (11) comprises a resonator (15) with an upper annular gap (16) surrounding the electron beam (14) in a radial way and a lower annular gap (17) surrounding the electron beam (14) in a radial way in the ion accelerator tank (1).
12. Apparatus according to one of the claims 10 to 11, characterized in that the power coupling (11) comprises a coupling stage (18) being arranged between annular gaps (16, 17) which coaxially surrounds the electron beam (14) and is arranged radially shifted and transversal to the ion beam (3) in the ion accelerator tank (1), wherein the coupling stage (18) is affixed to a drift tube attachment (19) of the ion beam (14).
13. Apparatus for high frequency power amplification, in particular for supplying an apparatus with a cavity for ion beam acceleration with high frequency power, comprising:

    a vacuum tank with a central tank axis for generating and accelerating a pulsed ion beam (14) along the tank axis,

    wherein
    a device (4) for forming and amplifying electron beam pulses according to claim 1 is arranged with its electron beam axis (5) transverse and shifted to a recipient axis (2) of an ion accelerator tank (1) and comprises outside of the ion accelerator tank (1)

    (a) an electron gun (6),

    (b) a high frequency deflector (7),

    (c) a direct voltage deflector (8),

    (d) a collector (9) with opposing field and

    (e) an after-accelerator (10)
    and comprises in the ion accelerator tank

    (f) a first gap as well as a second gap for coupling the power of the electron beam (14) to the ion beam (3) and

    (g) a main collector (13) for receiving the remaining power of the electron beam (14).
14. Apparatus according to claim 13, characterized in that an output circuit comprises a power coupling for feeding into a wave guide.
15. Apparatus according to claim 14, characterized in that the output circuit is implemented as a single-gap cavity.
16. A method for forming and amplifying electron beam pulses comprising the following method steps:

    generating an electron beam (14) by means of an electron beam gun (5),

    supplying the electron beam (14) with a transversal high frequency alternating field (20) under simultaneous high frequency deflection of the electron beam (14),

    high frequency gating out of up to 80 % of the electron beam energy to a collector (9) with opposing field by means of a high frequency deflector (7) and of a direct voltage deflector (8),

    after-accelerating the high frequency modulated electron beam (14) to electron beam pulses,

    coupling out the high frequency energy via a power coupling (11).
17. Method according to claim 16, characterized in that the coupling out of the high frequency energy is effected via a coax cable head (24) which extends with an antenna (23) into a ring resonator space (27) which communicates with the high frequency energy-rich electron beam (14) via an annular gap (25) surrounding the electron beam (14).
18. Method according to claim 16 or claim 17, characterized in that the coupling out of the high frequency energy is effected via a hollow conductor which extends with a coupling antenna into a ring resonator space (27) which communicates with the high frequency energy-rich electron beam (14) via an annular gap surrounding the electron beam (14).
19. Method according to one of the claims 16 to 18, characterized in that the coupling out of the high frequency energy is effected via a hollow conductor which is connected to a ring resonator (27) via a coupling window,
    wherein the resonator (15) communicates with the electron beam (14) via an annular gap (25) surrounding the electron beam (14).
20. Method according to one of the claims 16 to 19, characterized in that an electron beam (14) with high space charge constant according to the child-langmuir-equation is generated with an electron beam gun (6) with an electron beam from 20 A to 60 A, preferably 30 A to 50 A, at an acceleration voltage (U_c) of 20 kV to 60 kV, preferably 30 kV to 50 kV.
21. Method according to one of the claims 16 to 20, characterized in that the electron beam (14) is stabilised transversally by means of a longitudinal magnetic field in the brillouin-equilibriun.
22. Method according to one of claims 16 to 21, characterized in that the intensity modulated electron beam (14) excites a narrow band HF-resonator in the output circuit at an operating frequency (f).
23. Method according to one of the claims 16 to 22, characterized in that the electron beam (14) passes trough a homogeneous transversally aligned electric alternating field (20).
24. Method according to one of the claims 16 to 23, characterized in that between 50 % and 80 % of the electron beam energy is deflected from the electron beam axis (5).
25. Method according to one of the preceeding claims 16 to 24, characterized in that the deflected part of the electron beam is catched in a biased collector (9) with opposing field from -30 kV to -40 kV at an approximately constant electron energy from 30 keV to 50 keV.
26. Method according to one of the claims 16 to 25, characterized in that the energy of the catched electrons is collected in a collector (9) with opposing field and delivered to the cathode of the electron beam gun (6) as charging current.
27. Method according to one of claims 16 to 26, characterized in that the none-deflected electron packets are moved along the electron beam axis (14) in the time distance of an operating frequency (f) and
    enter into an output circuit (21) of the apparatus, which is designed as a resonator (15), at a main acceleration voltage between 200 and 400 kV.
28. Method according to one of the claims 16 to 27, characterized in that a resonator (15) starts up in the output circuit (21) of the apparatus,
    wherein high frequency fields in the resonator (15) absorb the energy of the electrons, decelerate them and feed an output conduction, preferable a coax cable head (24), and/or a hollow conductor.
29. Method according to one of the claims 16 to 28, characterized in that a remaining energy of the electrons is delivered in a main collector (13).
30. Method according to one of the claims 16 to 29, characterized in that for an electronic deflection in the high frequency deflector (7) for an operating frequency (f) the controlled high frequency signal consists of a main component at the frequency (f/2) and superposition of the frequency (5f/2) with an amplitude ratio of 5:1.
31. Method for accelerating ion beams which is executed with an apparatus comprising

    - an ion accelerator tank (1) with a central recipient axis (2) for guiding and accelerating of a pulsed ion beam (14) in the recipient axis (2) and

    - a device (4) for forming and amplifying electron beam pulses with an electron beam axis (5) for microstructuring and amplifying of current pulses for the supply of the apparatus for ion beam acceleration with high frequency power, wherein

    - the device (4) for forming and amplifying electron beam pulses is arranged with its electron beam axis (5) transverse and shifted to the recipient axis (2) and generates outside of the ion accelerator tank (1) an electron beam (14) with an electron gun (6), and

    - deflects by means of a high frequency deflector (7) and of a direct voltage deflector (8) more than 50 % of the electron beam current in a collector (9) with opposing field at frequencies from 100 MHz to 400 MHz in a clocked way for microstructuring the electron beam (14), and

    - an after-accelerator (10) introduces the electron beam (14) in the ion accelerator tank (1) at an acceleration voltage of several 100 Kilovolt, preferably at 200 to 400 Kilovolt, and

    - accelerates the ion beam (3) via a power coupling (11).
32. Method according to claim 31, characterized in that the electron beam (14) is subject to an intensity modulation corresponding to the operating frequency (f) of the ion beam (3).
33. Method according to claim 31 or 32, characterized in that the collector (9) with opposing field receives up to 80 % of the electron beam energy.

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