Device for impinging fluids and internal walls of hollow bodies with accelerated electrons

Abstract

The invention relates to a device for applying accelerated electrons to fluids and the inner walls of hollow bodies, comprising a cylindrical electron exit window (102) as part of a cylindrical housing (101) having a cylindrical axis (103) and enclosing an evacuable space; at least one wire-shaped, strand-shaped, rod-shaped, annular, helical, or cylindrical cathode (104a) arranged within the evacuable space and enclosed by the cylindrical electron exit window (102) and by a cylindrical control grid (104b), wherein the cylindrical control grid (104b) has a diameter smaller than the diameter of the cylindrical electron exit window (102), and wherein a first power supply device is electrically conductive between the wire-shaped, strand-shaped, rod-shaped, annular,a helical or cylindrical cathode (104a) and the cylindrical electron exit window (102) are connected, such that electrons can be emitted from the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) and accelerated radially away from the cylinder axis (103) of the cylindrical housing (101) in the direction of the cylindrical electron exit window (102), wherein a) a first hollow cylinder (107; 307) encloses the cylindrical electron exit window (102) and the first hollow cylinder (107; 307) and the electron exit window (102) are spaced apart from each other, so that a first annular free space is formed between the first hollow cylinder (107; 307) and the electron exit window (102); b) first support elements (105) of the cylindrical control grid (104b) and second support elements (106) of the concentrically arranged,cylindrical electron exit window (102) run centrally symmetrically to each other along the respective lateral surfaces and are arranged azimuthally within equal angular segments with an angle ω..

Description

[0001] The invention relates to a device for generating accelerated electrons, which can preferably be used to act on fluids and inner walls of hollow bodies.

[0002] Electron beam technology has been used on an industrial scale for several decades for the chemical modification, disinfection, and sterilization of a wide variety of materials and products. This treatment can be carried out economically at atmospheric pressure if the electrons are first released in a vacuum, then accelerated, and finally coupled into the treatment zone through a beam exit window, usually a thin metal foil. Acceleration voltages above 80 kV are typically required to penetrate sufficiently robust electron exit windows suitable for large-scale applications and to ensure adequate treatment depth within the product.

[0003] Various methods and beam sources are well-established for surface treatment of flat products such as plates and strips, while the all-around treatment of shaped bodies, bulk materials, the inner walls of hollow bodies, and fluids still presents challenges. For example, uniformly bombarding curved surfaces with electrons from all sides is geometrically problematic due to shadowing effects, variable absorption of electron energy in the gas path, and dose inhomogeneities resulting from differing projection ratios.

[0004] With existing source systems, such as axial emitters with a fast deflection unit or ribbon emitters (DE 196 38 925 C2) with an elongated cathode, both of which are usually operated with a heated thermionic cathode, all-round product treatment is only possible in a cumbersome manner, using additional equipment or with a high expenditure of equipment and / or technology and / or time.

[0005] For example, DE 10 2006 012 666 A1 describes a solution comprising three axial emitters with associated deflection control and three associated electron exit windows. The three electron exit windows are arranged such that they completely enclose a triangular space. If a substrate is passed through this space, its entire cross-section can be bombarded with accelerated electrons in a single treatment pass. However, if the substrate does not have the same triangular cross-section as the space enclosed by the three electron exit windows, the dose distribution from the bombardment with accelerated electrons on the substrate surface will be inhomogeneous. Furthermore, the equipment required for this embodiment is very complex, making this solution very expensive.

[0006] DE 4434 767 C1 discloses a device in which a bulk material stream falls between two area beam generators and can be actuated with accelerated electrons from both sides during this process. EP 0513 135 B1 describes such bilateral actuation of the freely falling bulk material stream using two mirror-image axial beam sources with scanners. Both solutions share the requirement of using two electron beam sources along with all their supply and control components, which still represents a significant equipment complexity.

[0007] DE 199 42 142 A1 discloses a device in which bulk material is passed in multiple free falls past a single area beam generator and bombarded with accelerated electrons. Due to the multiple passes, combined with intermediate mixing of the bulk material and the application of only a fraction of the total required target dose per pass, the probability is statistically higher in this embodiment that the particles of the bulk material are bombarded uniformly on all sides with accelerated electrons. However, the multiple passes require a considerable amount of time to carry out the treatment process.

[0008] A ring-shaped device for generating accelerated electrons is disclosed in DE 10 2013 111 650 B3, in which all essential components, such as the cathode, anode, and electron exit window, are ring-shaped, so that a ring-shaped electron beam can be generated by such a device, in which the accelerated electrons move towards the interior of the ring. Using just such a ring source, for example, bulk materials (DE 10 2013 113 688 B3) and gaseous media (DE 10 2019 134 558 B3) can be completely exposed to accelerated electrons from the outside. Likewise, strand-shaped substrates or medical packaging moved through the ring opening of the device, wherein the controllability of the dose transfer along the circumference (DE 10 2017 104 509 A1) and devices for stabilizing and online control of the processes (DE 10 2022 114 434 A1) are of particular importance.However, a disadvantage is that such ring sources are large in their construction due to the external cold cathodes, insulators and vacuum containers, and electron treatment of substrates can only be carried out in the relatively small volume of the ring interior and on external product surfaces.

[0009] DE 10 2018 111 782 A1 describes devices with cold cathodes that can also generate a ring of accelerated electrons, but in this case, the electrons move radially outwards. This arrangement, inverted with respect to the direction of electron propagation compared to DE 10 2013 111 650 B3, achieves a more favorable ratio between the size of the electron source and the volume of the treatment zone.

[0010] A disadvantage remains that the cold cathodes described in DE 10 2018 111 782 A1 emit electrons only as a result of stimulation by high-energy ions, which must be provided by an integrated plasma source, which always requires increased effort and larger installation space, especially at the very low pressures necessary for a plasma source to maintain the insulating capacity of the vacuum against gas breakdowns at the technologically required acceleration voltage.

[0011] Furthermore, this ring source is also affected by the weakness of all treatment setups equipped with only one electron source, namely the tendency for the energy dose to be deposited unevenly in the different surface areas of the material being treated (facing the electron exit window or those facing away from it). Improvement is to be achieved by the (time-consuming) multiple passes already described above or by electron reflectors on the back side of the material facing away from the electron exit window (although their dose contribution is several times lower than that applied by the primary beam electrons on the front side). Both methods can only mitigate the problem of insufficient dose homogeneity, but not solve it satisfactorily.

[0012] An additional requirement for a vertically elongated opening area of ​​an electron exit window arises from treatment technologies with high dose requirements, such as sterilization applications and the degradation of contaminants in fluids. This requirement stems from the fact that the electrons, accelerated inside the beam source, transfer some of their energy to the metal foil and the supporting grid as they pass through the electron exit window, causing them to heat up. Electron exit windows are therefore generally cooled, but to prevent thermal damage, the electron current density must still be limited. Given a technology-specific acceleration voltage, this corresponds to a similarly limited dose rate per unit area of ​​the electron beam source.An increase in the dose transferred to the material being treated is therefore only possible by a longer exposure time of the electrons, i.e. either by reducing the substrate velocity, which is undesirable for productivity reasons, or by extending the opening area of ​​the electron exit window in the transport direction of the substrates, for example the vertical falling direction of bulk material particles.

[0013] However, the latter cannot be achieved with the device described in DE 10 2018 111 782 A1, as it conflicts with the horizontal arrangement of cooling channels above and below the opening area of ​​the electron exit window, which is implicitly assumed in the cross-sectional drawings. It is known that the distance between these cold surfaces, to which the absorbed portion of the electron energy must be dissipated by heat conduction through the support grid, must not be too large (in practically implemented arrangements, it is limited to only about 7 to 10 cm), since the temperature rise of the metal foil and support grid increases linearly with the heat flux density and quadratically with the distance to the heat sink (i.e., the actively cooled edge of the opening area). The resulting limitation of the vertical extent of the uninterrupted opening area restricts not only the achievable uniformity but also the dose that can be applied to the material in a single pass.

[0014] Especially when processing fluids containing solid particles (such as exhaust gases), protecting the metal foils from the solid particles themselves is of paramount importance. Larger particles can directly damage the foil mechanically, while dust accumulation would impair electron transmission (thus reducing the dose transferred to the product) and increase the locally absorbed fraction of electron energy (thus promoting localized thermal damage to the metal foil and consequently vacuum leaks). Therefore, it is clear that process-related components for protecting the electron exit window are essential, but DE 10 2018 111 782 A1 does not disclose any technical teaching in this regard.

[0015] The invention is therefore based on the technical problem of creating a device for generating accelerated electrons that overcomes the disadvantages of the prior art. In particular, a device with a compact design is to be created with which both fluids and the inner walls of hollow bodies can be treated with accelerated electrons, achieving high dose values ​​in the treatment medium as well as a long continuous operating time.

[0016] The solution to the technical problem is achieved through objects having the features of claim 1. Further advantageous embodiments of the invention are set out in the dependent claims.

[0017] An inventive device for applying accelerated electrons to fluids and the inner walls of hollow bodies comprises a cylindrical electron exit window as part of a cylindrical housing having a cylindrical axis and enclosing an evacuable space; and at least one wire-shaped, strand-shaped, rod-shaped, annular, helical, or cylindrical cathode, which is arranged within the evacuable space and enclosed by the cylindrical electron exit window and by a cylindrical control grid. The cylindrical control grid has a diameter that is smaller than the diameter of the cylindrical electron exit window.Furthermore, a first power supply device is electrically connected between the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode and the cylindrical electron exit window, so that electrons can be emitted from the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode and accelerated radially away from the cylindrical axis of the cylindrical housing in the direction of the cylindrical electron exit window.

[0018] After the accelerated electrons have passed through the cylindrical electron exit window, a medium can be acted upon by the accelerated electrons outside the cylindrical electron exit window and in a ring-shaped manner around the cylindrical electron exit window. A device according to the invention further comprises a first hollow cylinder that encloses the cylindrical electron exit window, wherein the first hollow cylinder and the cylindrical electron exit window are spaced apart from each other. Thus, a first annular free space is formed between the first hollow cylinder and the cylindrical electron exit window, through which a fluid to be acted upon with accelerated electrons flows. Such a fluid can contain liquid, vaporous, and / or gaseous components.

[0019] Alternatively, the inner wall of a tube or hose to be bombarded with accelerated electrons, or at least partially and approximately, the inner wall of an arbitrarily shaped hollow body, can be associated with the first hollow cylinder. The area throughput required for a large-area, uniform dose application can be achieved by relative motion, whereby either the tube (or hose or arbitrarily shaped hollow body) or the beam source, or both, move.

[0020] Both a cylindrical electron exit window and a cylindrical control grid typically include support elements that provide the necessary mechanical stability. However, a disadvantage of such support elements is that they negatively affect the trajectory of accelerated electrons striking them, or in the worst case, completely absorb their energy. This energy, previously supplied by the high-voltage power supply, is thus diverted from the treatment process, impairing its energy efficiency and leading to thermal stress on the electron source.In a device according to the invention, a further essential feature is that the first support elements of the cylindrical control grid and the second support elements of the concentrically arranged cylindrical electron exit window are aligned centrally with each other along their respective lateral surfaces and arranged azimuthally within equal angular segments with an angle ω. In a preferred embodiment, the first support elements of the cylindrical control grid and the second support elements of the cylindrical electron exit window run parallel to the cylinder axis and are arranged within equal first angular segments with an angle ω.

[0021] Such first angular segments with angle ω are hereinafter also referred to as shading angle segments or shading angle regions. A device according to the invention comprises several of these shading angle segments, which in a preferred embodiment are spaced apart from one another by the same angular dimension. In a device according to the invention, second angular segments are thus formed between the shading angle segments, in which the accelerated electrons are not obstructed by support elements of the cylindrical electron exit window and the cylindrical control grid running parallel to the cylinder axis. This results in a higher electron dose in these angular segments compared to the prior art, with which a fluid or the inner wall of a hollow body can be impinged.

[0022] In a device according to the invention, electrons are emitted from a centrally arranged cathode, which may be wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical, or cylindrical and extends along the axis of the cylindrical housing. The cathode can be configured, for example, as a thermionic cathode or a plasma cathode. As a plasma cathode, it is preferably rod-shaped or cylindrical. In a preferred embodiment, the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical, or cylindrical cathode carries an electric current, is thereby heated, and thus acts as a thermal emitter, i.e., a thermionic cathode. For this purpose, the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical, or cylindrical cathode is electrically connected to the negative terminal of a first power supply unit.The positive terminal of the first power supply is electrically connected to the cylindrical electron exit window, so that it has an electrically positive potential relative to the control grid and cathode.

[0023] In a simple embodiment, the electron exit window is at ground potential. More complex technological applications, which will be described below, can benefit from electrically isolating the electron exit window from ground and defining or varying its electrical potential using an intermediate (DC, AC, or pulsed) voltage source.

[0024] Due to the positive potential applied to the cylindrical electron exit window relative to the cathode, the electrons emitted from the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical, or cylindrical cathode are accelerated radially outwards towards the cylindrical electron exit window. After passing through the cylindrical control grid and exiting the cylindrical electron exit window, the accelerated electrons traverse the first ring-shaped free space and strike the inner wall of the first hollow cylinder.

[0025] If a fluid within the first annular space is to be bombarded with accelerated electrons, it is advantageous if at least the inner surface of the first hollow cylinder, at least in the region opposite the electron exit window, consists of a material that reflects electrons well. In this way, the electrons that reach the inner surface of the first hollow cylinder can be reflected by the cylinder and contribute again to bombarding the fluid with accelerated electrons. The aforementioned region of the first hollow cylinder can consist entirely of an electron-reflecting material, or the inner surface of this region can be coated with such a material.A suitable material for reflecting electrons is, for example, a temperature-resistant metal with a high atomic number, such as tungsten or a tungsten alloy. It is advantageous if at least the electron-reflecting area of ​​the first hollow cylinder is cooled so that it does not heat the air in the treatment zone of the first annular free space. Such cooling can, for example, be implemented as water cooling.

[0026] In a further embodiment of the invention, the cylinder axis of the cylindrical housing is aligned perpendicular to the Earth's surface, so that, for example, a liquid film to be charged with accelerated electrons can run down the inner wall of the first hollow cylinder. Since it is not always possible, particularly in the case of a mobile system, to align the system so that the cylinder axis is perfectly perpendicular, the alignment of the cylinder axis of the cylindrical housing can also deviate from a perpendicular to the Earth's surface by an angle of approximately 10° or less.

[0027] The invention is described in more detail below with reference to exemplary embodiments. The figures show: Fig. 1 a schematic representation of a horizontal section of a device according to the invention; Fig. 2 a schematic representation of a vertical section of the device according to the invention. Fig. 1 Fig. 3 a schematic representation of a horizontal section of a first alternative device according to the invention; Fig. 4 a schematic representation of a vertical section of the first alternative device according to the invention. Fig. 3 Fig. 5 a schematic representation of a horizontal section of a second alternative device according to the invention; Fig. 6 a schematic representation of a vertical section of the second alternative device according to the invention. Fig. 5 Fig. 7 a schematic representation of a horizontal section of a third alternative device according to the invention; Fig. 8 a schematic representation of a vertical section of the third alternative device according to the invention. Fig. 7 ; Fig. 9 a component 900 of a device according to the invention.

[0028] In the Fig. 1 and 2 is one and the same device according to the invention 100 schematically represented, wherein Fig. 1 a horizontal section and Fig. 2 The figure shows a vertical section. The device 100 comprises a cylindrical housing 101, which encloses an evacuable space. A vacuum can be maintained within the evacuable space by means of at least one vacuum pump, which is not shown in the figures for clarity but is known from the prior art. A wall region of the housing 101 is designed as a cylindrical electron exit window 102. The cylindrical housing 101 has a circular cross-section and a cylinder axis 103 oriented perpendicular to the Earth's surface and encloses a centrally arranged cathode 104a.

[0029] It should be noted that in this embodiment and the embodiments described below, the cylinder axis 103 is only oriented perpendicular to the Earth's surface by way of example. In a device according to the invention, the cylinder axis 103 can alternatively have any other angle to the Earth's surface. In a preferred embodiment, however, the cylinder axis (103) of the cylindrical electron exit window (102) is oriented perpendicular to the Earth's surface or at an angle of approximately 10° or less from the vertical.

[0030] The cathode 104a is rod-shaped, extends along the cylinder axis 103, and consists of a wire through which an electric current flows. In one embodiment, the thermionic cathode comprises a ceramic rod around which a wire is wound helically. The material of the cathode 104a can, for example, contain at least one of the chemical elements tungsten or tantalum. Due to the current flow, the cathode 104a is heated, which in turn leads to the thermal emission of electrons. The cathode 104a is thus designed as a thermionic cathode. The electrons emitted by the cathode 104a are accelerated radially outwards towards the cylindrical electron exit window 102 because the cylindrical electron exit window 102 has an electrical anode potential.For this purpose, the cylindrical electron exit window 102 is electrically connected to the positive terminal of a first power supply unit, and the cathode 104 is connected to the negative terminal of the first power supply unit. For the sake of clarity, the first power supply unit is not shown in the figures. The device 100 is thus designed as a cylindrical electron beam generator, which generates a ring of accelerated electrons whose movements are directed radially outwards.

[0031] However, forming the cathode of a device according to the invention as a thin wire, as in cathode 104a, also entails additional requirements. The high operating temperature of the wire, required for thermal emission of electrons, leads to recrystallization of the wire material and changes in the wire's length. If the wire is made of metal, an increase in temperature generally results in elongation. However, the elongation of a vertically clamped wire leads to its compression and bending, so that it no longer runs exactly along the cylinder axis 103. This can negatively affect the homogeneity of the overall electron emission and ultimately the dose distribution on the material being treated. The embrittlement of a metal wire, also associated with recrystallization, can even lead to breakage as a result of this compression, especially under thermal cycling.As an alternative to a metal wire, carbon fibers can also be used as the filament, so that the filament is formed in strand form. However, such carbon fibers contract when the temperature increases. If rigidly clamped, this results in high tensile stresses that would lead to the filament cracking.

[0032] Therefore, in a device according to the invention, it is advantageous to clamp a wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical, or cylindrical annealing cathode firmly only at its upper end, while it is guided radially at the bottom but mounted to be axially movable. When the device is operated vertically, the upper end corresponds to the end furthest from the direction of the Earth's gravity vector. It is advantageous to connect the annealing cathode at its lower end with a clamping element that, by means of its weight, always maintains a moderate tensile stress sufficient to tighten the cathode wire without causing it to slip or break. Alternatively, the annealing cathode can also be clamped or supported only at its lower end and connected at its upper end with an axially movable clamping element.When the device is operated vertically, the lower end corresponds to the end that is closer to the direction of action of the Earth's gravity vector.

[0033] When a thermionic cathode is heated directly by an electric current, an electrical potential gradient inevitably develops along its length. This gradient leads to a change in the electric field strength and thus in the electron emission along the length of the cathode. To achieve a more uniform distribution of electron emission along the length of the cathode, the potential gradient must be minimized. This can be accomplished by heating the cathode indirectly (for example, by conduction, radiation, or electron impact).

[0034] In a suitable embodiment, a rod-, strand-, or wire-shaped heating element is arranged inside a cylindrical annealing cathode, centrally along the cylinder axis and electrically insulated from the cylinder wall. This element is heated by passing an electric current through it. The heating element must operate at a high temperature to heat the cathode to its emission temperature and is therefore made of a material with a high melting point (greater than 1500 K). Suitable materials include refractory metals (such as tungsten, tantalum, or molybdenum) or carbon fibers.

[0035] In a first variant of this embodiment, a high-temperature resistant, electrically low conductive material (such as boron nitride or zirconium oxide) is introduced between the central heating element and the cylindrical annealing cathode, and the heat from the central heating element is transferred to the cylindrical annealing cathode by thermal conduction.

[0036] In a second variant of the aforementioned embodiment, the heating element and the cathode are mounted without contact, and the heat from the central heating element is transferred to the cylindrical cathode by thermal radiation. A particularly advantageous embodiment of this variant is achieved by connecting the central heating element and the cylindrical cathode at one end via an electrical conductor and returning the current through the heating element via the cylindrical wall of the cathode. This compensates for the magnetic field associated with the heating current, which undesirably influences electron propagation (i.e., its cancellation in the external environment of the cathode). The cylindrical wall of the cathode is made sufficiently thick so that it has low electrical resistance, thus ensuring that the longitudinal potential gradient remains as low as desired.This results in a more homogeneous extraction field around the emission surface of the cylindrical annealing cathode and thus a more uniform electron emission distribution along the longitudinal axis of the annealing cathode.

[0037] In a third variant of the aforementioned embodiment, the heating element and the cathode are also mounted without contact and are completely electrically insulated from each other. The cathode can then be connected to the positive terminal and the heating element to the negative terminal of an additional power supply. When the heating element is heated to its emission temperature, the electrons it emits are attracted to the inner wall of the cathode and heat it through electron collisions.

[0038] In all three described variants, it is advantageous to make the cylindrical cathode from a material with a high melting point (greater than 1,500 K) and a moderate to low work function (less than 5 eV). Suitable materials include, for example, refractory metals (tungsten, tantalum, molybdenum, niobium), as well as titanium, zirconium, or stainless steel, all of which can also be coated with compounds (such as oxides) to lower the work function, and ceramics with a high melting point (such as rare-earth borides, with lanthanum hexaboride being the best-known example).

[0039] Even the indirect heating of a cylindrical annealing cathode leads to a change in its length. With such a geometry, it is advantageous to clamp or support the annealing cathode at its lower end and to enable stress-free length compensation through an axially movable, radially guided upper clamping and contact.

[0040] Furthermore, for all embodiments of a thermionic cathode, it is advantageous to provide radial adjustability of the upper and lower clamping and contacting points in order to achieve optimal alignment of the thermionic cathode along the vertically oriented cylinder axis 103 and thus a uniform field strength as well as a resulting uniform electron emission along the entire cathode circumference.

[0041] In a device according to the invention, such as device 100, the cathode 104a is further enclosed by a cylindrical control grid 104b, which has a diameter smaller than the diameter of the cylindrical electron exit window 102. The grid structure of the cylindrical control grid 104b is fully developed. The cylindrical control grid 104b consists of an electrically conductive material, is electron-transparent, and has an electrical potential that is slightly more positive than the electrical potential of the cathode 104a. In one embodiment, the cylindrical control grid 104b has a voltage difference relative to the cathode 104a of approximately +20 V to approximately +2,000 V.The voltage potential for the cylindrical control grid can be supplied by a separate second power supply unit or, alternatively, by a separately adjustable second channel of the first power supply unit. The cylindrical control grid 104b, as an electron-transparent gauze cylinder, reduces the electric field strength inside the cylinder, allows for the installation of optional supports for the cathode wire along its longitudinal extent, and ensures uniform, all-around electron extraction, tolerant to certain positional deviations of the cathode wire, independent of the accelerating voltage acting externally. Furthermore, the adjustable voltage difference between the control grid and the cathode, in addition to varying the heating current flowing through the cathode wire, offers a second, highly dynamic means of controlling the emitted electron current.A similar cylindrical control grid in combination with a cathode wire is already known from prior art bandpass radiators. Therefore, for base elements for clamping the cathode wire and the cylindrical control grid 104b in a device according to the invention, design solutions known from prior art bandpass radiators, such as those from DE 196 38 925 C2, can also be used.

[0042] To provide mechanical stability to the cylindrical control grid 104b and the cylindrical electron exit window 102, both components have support structures. Such support structures can include support elements running parallel to the cylinder axis 103 and also support elements that run in a ring around the cylinder axis. A disadvantage of such support structures, which are also known from the prior art, is that accelerated electrons striking a support structure transfer at least some of their energy into the support structure, which is then no longer available to impinge a fluid.According to the invention, first support elements 105 of the cylindrical control grid 104b, extending parallel to the cylinder axis 103 of the cylindrical housing 101, and second support elements 106 of the electron exit window 102, extending parallel to the cylinder axis 103, are arranged within the same first angular segments with an angle ω. Adjacent first angular segments are spaced apart from each other by the same angular measure. If a device according to the invention also includes means for cooling the control grid 104b and / or for cooling the electron exit window 102, then cooling elements extending parallel to the cylinder axis 103 are preferably arranged within the first angular segments. The same applies to signal or control lines that extend through or within the cylindrical housing parallel to the cylinder axis 103.

[0043] A device according to the invention, such as device 100, thus has first angular segments (the so-called shadowing angle regions) within which no medium can be exposed to accelerated electrons, but such a device also has second angular segments between the first angular segments within which no support elements of the control grid 104b and the electron exit window 102 running parallel to the cylinder axis 103 negatively influence the trajectory of accelerated electrons and within which therefore a medium with a high density of accelerated electrons can be exposed.

[0044] The device 100 according to the invention further comprises a first hollow cylinder 107, which encloses the cylindrical electron exit window 102, wherein the first hollow cylinder 107 and the electron exit window 102 are spaced apart from each other. The cylinder axis of the hollow cylinder 107 and the cylinder axis of the cylindrical electron exit window are identical and correspond to the cylinder axis 103 of the cylindrical housing 101, so that a first annular free space 108 is formed between the hollow cylinder 107 and the cylindrical electron exit window 102.

[0045] As previously explained, the cylindrical electron exit window 102 has a positive electrical potential relative to the control grid and cathode, so that the electrons emitted from the current-carrying cathode 104a are initially accelerated towards the cylindrical electron exit window 102. After exiting the cylindrical electron exit window 102, the accelerated electrons traverse the first annular free space 108 and thereby impinge upon a liquid, gaseous, or vaporous fluid that is moving through the first annular free space 108. A liquid, gaseous, or vaporous fluid is subsequently referred to as the material to be treated. Furthermore, the region of the first annular free space 108 within which a material to be treated can be impinged upon by accelerated electrons is subsequently also referred to as the treatment zone.

[0046] To improve the homogeneity of the dose of accelerated electrons introduced into a treatment material, the radial distance between the cylindrical electron exit window 102 and the first hollow cylinder 107 is set smaller than the electron range in the treatment material to be penetrated, so that only a section of the entire depth dose distribution with thereby defined limited variability acts on the area filled with treatment material.

[0047] Depending on the temperature regime required by the technology within the treatment zone, the first hollow cylinder 107 can optionally be water-cooled or thermally insulated. In the latter case, the energy of the electrons it absorbs or the thermal contact with the material being treated leads to its heating until it reaches temperature equilibrium with its surroundings through heat radiation.

[0048] In addition, for further optimization of the radial dose compensation, it is advantageous to design the first hollow cylinder 107 as a so-called electron reflector, which backscatters at least some of the electrons not absorbed by the material being treated into the treatment chamber and onto the outer surface of the material being treated (facing away from the electron exit window 102). An electron reflector typically consists of a temperature-resistant metal with a high atomic number, preferably tungsten, which exhibits a particularly high backscattering coefficient, or of a less expensive construction material, which is provided on the inner wall of the first hollow cylinder 107 with a layer of the aforementioned ("refractory") metals or a compound such as tungsten carbide, the thickness of which is dimensioned such that the incident and non-reflected electrons can be completely decelerated within it.

[0049] If, on the other hand, minimizing parasitic X-ray radiation is pursued as a further optimization goal in a device according to the invention, it is more advantageous to design the first hollow cylinder 107 as a so-called electron absorber, i.e., to construct it from a temperature-resistant material of low atomic number, such as carbon or light metal carbides, which (at the cost of a similarly low backscattering coefficient for electrons) release only a few and also low-energy X-ray photons when the electrons are slowed down.

[0050] In a device according to the invention, such as device 100, the electrons absorbed by the first hollow cylinder 107 must be dissipated in a defined manner to prevent the first hollow cylinder 107 from becoming electrically charged. In the simplest case, it is sufficient to make the first hollow cylinder 107 electrically conductive and to connect it to ground potential.

[0051] More complex technological tasks, which will be described below, can benefit from electrically isolating the first hollow cylinder from ground and defining or varying its electrical potential by means of an intermediate (DC, AC or pulsed) voltage source.

[0052] In a further embodiment, the first hollow cylinder is advantageously used as an inline quality control system for the spatially and temporally resolved measurement of the electron current density incident from the electron exit window 102. For this purpose, a number of sensors (for example, designed as sheets) are arranged electrically insulated from ground and from each other on the inner wall of the first hollow cylinder 107 and distributed across its circumference and height. These sensors act as electron collectors and make the locally absorbed electron current individually accessible to an evaluation unit. The spatial resolution, but also the measurement effort, increases with the number of sensors. Therefore, the achievable precision of such an inline quality control system and the associated effort must be weighed against each other depending on the application.If such a measuring device first records values ​​without and then with the material being treated, the evaluation of these values ​​allows conclusions to be drawn about the vertical and azimuthal uniformity of the output current density emitted by the electron source, its temporal constancy, and the resulting dose homogeneity on the material being treated in the subsequent process. During technological operation, i.e., with the material being treated, the change in the leakage current distribution measured on the inner wall of the first hollow cylinder 107, compared to the output current density determined without the material being treated, is a measure of the amount of energy absorbed by the material being treated, again with spatial and temporal resolution. A change in the absolute value due to a change in the beam parameters, either manually by an operator or automatically by a control program, can be taken into account and calculated back into the evaluation unit.

[0053] In one embodiment, the wall of the first hollow cylinder 107 is completely closed. With such a first hollow cylinder 107 and the features of the device 100 described above, fluid treatment can be achieved in the simplest case by allowing the fluid to flow (or be sprayed) across the entire cross-section of the treatment zone past the electron exit window in the direction of the cylinder axis, whereby the fluid is also in direct contact with the cylindrical electron exit window 102 and can additionally cool it.In an alternative approach, where the fluid to be treated with accelerated electrons is a liquid, it can, under the influence of adhesion and gravity, flow down the outer wall of the cylindrical electron exit window 102, the inner wall of the first hollow cylinder 107, or both simultaneously, as a thin, uniform film of liquid. A cooling gas must then flow through the resulting open cross-section of the annular free space 108. An inert cooling gas merely prevents overheating of the electron exit window 102 and / or the fluid, while a reactive cooling gas can simultaneously contribute to the chemical modification of the fluid.

[0054] For reasons of energy efficiency and to reduce the thermal load on the electron source, it is advantageous to prevent electrons from striking the electron exit window 102, its horizontal boundaries, and vertical support and cooling structures outside the upper and lower end faces of the opening regions, and especially within the shadowing angle regions. This is because electrons would be absorbed and thus contribute to the parasitic heating of the electron beam generator, but not to its technological dose rate. To this end, the cylindrical control grid 104b and / or the electron exit window 102 can be designed such that they are not completely transparent to electrons, but rather have defined opening regions that align with the angular regions of the electron exit window 102 not covered by shadowing angle regions with angle ω.Electrons emitted from the thermionic cathode that strike the control grid 104b in the closed shadowing angle region are absorbed there and do not reach the electron exit window 102. Since they only traverse a small potential difference and thus absorb little energy, this beam-shaping absorption at the control grid does not represent a significant loss factor.

[0055] In another alternative embodiment, the first hollow cylinder 107 is designed as part of a hollow body whose inner wall is to be bombarded with accelerated electrons. Because of the previously described shielding angle segments, it is advantageous in such an application if the first hollow cylinder 107 and / or the cylindrical housing 101 perform a rotational movement about the cylinder axis 103 in order to bombard the entire inner wall of the hollow cylinder 107 with accelerated electrons.

[0056] In the Fig. 3 and 4 A first alternative device 300 according to the invention is shown schematically, wherein Fig. 3 a horizontal section and Fig. 4 a vertical section is shown. Device 300 initially exhibits all features, feature variants, and technical functionalities of device 100 from the Fig. 1 and 2In contrast, the device 300 comprises a first hollow cylinder 307, the wall of which is not completely closed, but rather has a plurality of openings 309. These openings 309 can, for example, be configured as pores, holes, or slots. For the purpose of introducing a working gas into the fluid to be treated, the device 300 comprises a second hollow cylinder 310, which surrounds the first hollow cylinder 307 and defines a second annular space 311 between the first hollow cylinder 307 and the second hollow cylinder 310. The working gas can then be introduced into the second annular space 311 at overpressure, having passed through the openings 309 of the first hollow cylinder 307 into the first annular space 108.

[0057] If a fluid to be treated with accelerated electrons is in the form of a liquid, the introduction of a working gas through pore-shaped openings 309 of the hollow cylinder 307 leads to the formation of microbubbles within the liquid and to its intensive turbulence. This in turn causes a statistical dose equalization within the liquid volume and leads to a decreasing density within the liquid and thus (given a minimum selectable accelerating voltage) to an increasing range of the accelerated electrons.

[0058] A reactive working gas (for example, oxygen) can be chemically converted under the influence of the accelerated electrons (for example, oxygen into ozone) and contribute to a further increase in the reactivity or the desired chemical effect of the irradiation process.

[0059] In the Fig. 5 and 6A second alternative device according to the invention 500 is shown schematically, wherein Fig. 5 a horizontal section and Fig. 6 a vertical section is shown. Device 500 initially exhibits all features, feature variants and their technical functionalities of device 100 from the Fig. 1 and 2 or alternatively, all features, feature variants and technical functionalities of the device 300 from the Fig. 3 and 4The device 500 additionally comprises a third hollow cylinder 512, the diameter of which is larger than the diameter of the cylindrical electron exit window 102, but smaller than the diameter of the first hollow cylinder 107. The cylinder axes of the first hollow cylinder 107, the third hollow cylinder 512, and the electron exit window 102 are identical. The third hollow cylinder 512 thus divides the first annular free space 108 into an inner annular free space 513 and an outer annular free space 514. A fluid to be subjected to accelerated electrons is guided through the outer annular free space 514, and a protective gas is guided through the inner annular free space 513.The protective gas, which also cools the cylindrical electron exit window 102, ensures that the fluid, which may contain dirt or other particles, does not exert any mechanical contact on the electron exit window, thus improving the service life of the cylindrical electron exit window 102.

[0060] Particularly when a fluid to be treated with accelerated electrons is gaseous and mixing of the gas to be treated with the protective gas is not critical, the third hollow cylinder 512 can be designed as a grid, for example as a gauze fabric. If, on the other hand, liquids or suspensions are to be treated with accelerated electrons and their mixing with the protective gas is to be avoided, it is advantageous if the third hollow cylinder 512 is designed as a completely closed, but thin film that reliably separates the fluid to be treated and the protective gas, but is sufficiently transparent to allow the passage of accelerated electrons. In alternative embodiments, such a film can also be perforated.

[0061] If, however, the treatment of the fluid flowing in the outer annular space 514 is to be deliberately supported by a (inert or reactive) working gas, the wall of the third hollow cylinder 512 can be provided with pore-, hole-, or slot-shaped openings, and an overpressure can be maintained in the inner annular space 513 relative to the outer annular space 514. This prevents the fluid to be treated from reaching the electron exit window 102, while simultaneously allowing the protective gas to enter the fluid flowing in the outer annular space 514 from the inner annular space 513. If the fluid is a liquid, this occurs in the form of microbubbles, which reduce the density of the liquid (thus increasing the electron range) and swirl it (thus promoting the uniformity of the applied dose).If an oxygen-containing working gas is used as a protective gas, ozone is already formed in the inner ring-shaped free space 513 (with increased yield compared to that associated with . Fig. 3 and 4 (described embodiment) and, for example, intensifies the pollutant removal in wastewater intended by electron treatment. Alternatively, the first hollow cylinder 107 can also be provided with openings for the addition of the working gas, and it can be forced from the outside into the outer annular free space.

[0062] If the electron treatment is intended to effect plasma-chemical reactions, such as the degradation of pollutants in (combustion or industrial) exhaust gases, the splitting of greenhouse gases (such as carbon dioxide or methane), or the conversion of multi-component gas mixtures (for example, for the synthesis of chemical energy storage media), then a further embodiment of the invention is advantageous, wherein the first hollow cylinder 107 is electrically insulated from the third hollow cylinder 512 and the latter is electrically connected to the electron exit window 102. An electrical voltage can be generated between the first hollow cylinder 107 and the third hollow cylinder 512 by means of a third power supply device, which is suitable for igniting and maintaining a plasma within the outer annular free space 514.A particularly advantageous choice of voltage difference is such that a non-self-sustaining glow discharge, supported by the beam electrons, forms in the outer annular free space 514. This discharge is characterized by the fact that it stabilizes as a large-area, uniform volume discharge even in rough vacuum or at atmospheric pressure (i.e., it prevents its conversion to a filament or arc discharge), and the energy of the plasma electrons can be selectively tuned to excite plasma-chemically active intramolecular vibrational states of the reactants. This requires a voltage of 1 kV to 5 kV per 1 cm of radial distance between the first hollow cylinder 107 and the third hollow cylinder 512. Particularly high power density and energy efficiency of this plasma are achieved when the energy supply is pulsed by the third power supply unit.

[0063] It is known that plasmas, while not having deep-penetrating effects, do exert at least near-surface chemical and disinfectant effects on media exposed to them. This enhances the effects of electron treatment, even if the first hollow cylinder 107 represents part of the inner wall of a hollow body, which must possess sufficient electrical conductivity for this purpose.

[0064] It is in principle possible to connect the third hollow cylinder 512, and with it the electron exit window 102, to ground potential and to apply the differential voltage supplied by the third power supply device to the first hollow cylinder 107. However, it appears advantageous to reverse this, i.e., to connect the first hollow cylinder 107 to ground potential and the third hollow cylinder 512, as well as the electron exit window 102, to the differential voltage potential.

[0065] The latter variant allows the first hollow cylinder 107 to be considered as the continuous wall of a long pipeline (for example, in a chemical plant or as the exhaust system of a ship's engine), into which the electron source (consisting of cathode 104a, control grid 104b, electron exit window 102) is electrically insulated and installed, protected by the third hollow cylinder 512, which acts as the counter electrode for the electron beam-supported hybrid plasma. Aerodynamically shaped end pieces above and below the cylindrical electron source, which is integrated with the third hollow cylinder 512, ensure a largely turbulence-free flow of the fluid to be treated around the components installed in the center of the surrounding pipeline.

[0066] In the Fig. 7 and 8 A third alternative device according to the invention 700 is shown schematically, wherein Fig. 7 a horizontal section and Fig. 8 Figure 700 shows a vertical section of the device 700. The device 700 initially exhibits all features, feature variants, and the corresponding technical functionalities of the device 500 described in the figure. Fig. 5 and 6 on.

[0067] In addition, the device 700 also includes a number of gas tubes 715, which extend within the inner annular free space 513 parallel to the cylinder axis 103 of the cylindrical housing 101. The gas tubes 715, with their orientation described above, constitute, as an assembly, the component that enables the desired free scalability of the axial length (vertical extent) of the cylindrical electron source and its function-determining components for higher dose rates. In a preferred embodiment, all gas tubes 715 are spaced from the cylinder axis 103 of the cylindrical housing 101 by an identical first dimension and from each adjacent gas tube 715 by an identical second dimension. In the embodiment described in the exemplary embodiment, the gas tubes 715 have a rectangular cross-section.Alternatively, other geometric shapes for the cross-section of the gas tubes 715, such as a circular cross-section, are also possible. Each gas tube 715 has bores 716 on two opposite wall regions along its longitudinal extent, through which gas can be introduced into the inner annular free space 513. The bores 716, which are formed in the gas tubes 715 with a preferred diameter of about 1 mm or less, extend at least over a gas tube length region that is opposite the cylindrical electron exit window 102 and thus corresponds to the height of the cylindrical electron exit window 102.The bores 716 are preferably provided in the gas tubes 715 and the gas tubes 715 are oriented such that the direction of gas exit through a bore 716 runs within a horizontal plane of the device 700 and is perpendicular to a straight line 717 drawn from the cylinder axis 103 of the cylindrical housing 101 to the center point of a horizontal cross-sectional surface of an associated tube 715. The direction of gas exit through the bores 716 is in . Fig. 7 This is illustrated by arrows on the gas pipes 715. The gas can be, for example, air or an inert gas. For the sake of completeness, it should be mentioned that the gas pipes 715 are connected by means of a piping system to a reservoir containing the gas. The reservoir can also comprise the ambient air of a device according to the invention.

[0068] Instead of the individual bores 716, a vertical slot can alternatively be provided in the walls of the gas pipes 715 on the opposite wall sections, extending over the height of the electron exit window 102. The vertical slot has a width of approximately 1 mm or less, in any case such that its cross-section is smaller than that of the supplying gas pipe, thus achieving a uniformity of the hydrostatic pressure in the gas pipe and, consequently, of the gas outflow from the slot. (This consideration also applies to the total cross-section of the alternative bores in relation to that of the gas pipes.)

[0069] If a gaseous fluid is to be treated with accelerated electrons, flowing through the outer annular space 514, or a liquid fluid is to be treated, merely trickling down the inner wall of the first hollow cylinder 107 as a liquid film, the third hollow cylinder 512 can be designed as a grid. For this purpose, for example, a gauze material consisting of a wire mesh can be used. In such an embodiment of the device 700, the gas introduced into the inner annular space through the bores 716 escapes to the outside through the grid-shaped third hollow cylinder 512 and is discharged in the outer annular space 514 along with the flow of the fluid to be treated with accelerated electrons. The gas flowing through the bores 716 thus fulfills two functions.Firstly, the gas escaping outwards through the third hollow cylinder 512 prevents dust particles from passing through the third hollow cylinder 512 inwards towards the electron exit window 102, thus protecting the electron exit window 102 from a parasitic coating of dust particles. The gas is therefore subsequently referred to as a protective gas. Secondly, the flow of the protective gas within the inner annular free space 513 simultaneously cools the cylindrical electron exit window 102. Consequently, the water cooling system for a supporting grid for the electron exit window 102 can be made smaller.

[0070] It is advantageous if the gas pipes 715 have mechanical contact with the third hollow cylinder 512, or if the gas pipes 715 are mechanically connected to the third hollow cylinder 512. This mechanically stabilizes the third hollow cylinder 512 and holds it in position. The gas pipes 715 and the third hollow cylinder 512 are then, for example, designed as a compact assembly that can be removed as a single unit during maintenance work.

[0071] In another embodiment, the diameter of the third hollow cylinder 512 is selected such that its cylindrical wall is arranged centrally between the first hollow cylinder 107 and the cylindrical electron exit window 102.

[0072] In another embodiment, the ring width of the inner annular free space 513 is selected such that the gas tubes 715 fill at least 90% of the distance between the cylindrical electron exit window 102 and the third hollow cylinder 512.

[0073] However, a disadvantage of using the gas tubes 715 in a device according to the invention is that the gas tubes 715 are not sufficiently transparent to accelerated electrons. Therefore, according to the invention, the gas tubes 715 are also arranged in the shadowing angle regions with the angle ω.

[0074] In a further embodiment, if liquids, abrasive suspensions and / or sprayed aerosols are used as the fluid flowing through the outer annular free space, the third hollow cylinder 512 is preferably designed as a thin film that is sufficiently transparent to allow the passage of accelerated electrons. Such a film protects the cylindrical electron exit window 102 from mechanical impact by the fluid.

[0075] It has already been described that gas is introduced into the inner annular free space 513 by means of gas tubes 715. Particularly when the third hollow cylinder 512 is designed as a thin film, the gas tubes 715 can alternatively perform two different functions. In this case, gas is introduced into the inner annular free space 513 by means of a first group of gas tubes 715, and the gas is extracted from the inner annular free space 513 by means of a second group of gas tubes 715. Preferably, a gas tube 715 of the first group is always arranged adjacent to a gas tube 715 of the second group.

[0076] It has been explained repeatedly that it is not possible to apply a sufficient dose of accelerated electrons to a fluid within the shadowing angle regions with angle ω. Therefore, all previously described embodiments include mechanical means, so-called "dead zone shields," which prevent a fluid intended to be exposed to accelerated electrons from entering the shadowing angle regions. These mechanical means can include apertures that cover the shadowing angle regions on the inlet side, i.e., on the side where a fluid flows into the first annular free space 108 or the outer annular free space 514. Furthermore, these mechanical means can also include walls that extend parallel to the cylinder axis 103 through the first annular free space 108 or the outer annular free space 514.extend the outer ring-shaped free space 514 and separate the shadow angle areas from the second angle areas of the treatment zone located in the circumferential direction between them.

[0077] A further embodiment of the invention achieves a more uniform treatment dose in the flowing fluid without the need for dead-zone shielding in the treatment chamber. In this embodiment, the shading structural elements of the previously described devices (i.e., the first support elements 105 of the cylindrical control grid 104b; the second support elements 106 of the electron exit window 102; and, from device 700 onward, the gas tubes 715) are still aligned along their respective corresponding lateral surfaces and are centrally symmetrical, but no longer parallel to the common central cylinder axis, rather in the form of a helical curve. The slope of this curve is selected such that, after traversing the (approximately) vertical opening length of the electron exit window, an azimuthal rotation by an angle Ω is achieved.Where Ω is the angle whose vertex lies on the cylinder axis and whose legs pass through the midpoint of two adjacent shading structural elements. Regarding the aforementioned lateral surfaces, it should be noted that the control grid 104b is to be considered the lateral surface for the first support elements 105; the electron exit window 102 is to be considered the lateral surface for the second support elements 106; and the third hollow cylinder 512 is to be considered the lateral surface for the gas tubes 715. In . Fig. 9 Figure 900 schematically depicts a component of a device according to the invention, which comprises an electron exit window 102. The following is shown only by way of example: Fig. 9A single second support element 906 is shown, which is intended to illustrate the orientation of electron-shading structural elements such as first and second support elements, as well as gas tubes 715, in such an embodiment. The second support element 906, which is shown with dotted lines, extends in a helical curve along its associated surface, the electron exit window 102, from top to bottom, with the slope of the helical curve being very steep. It should be noted that, even in such an embodiment, the electron-shading structural elements, such as first and second support elements and, if applicable, gas tubes 715, are all arranged within the first angled elements at the angle ω, but the angle ω along the cylinder axis 103 rotates around the cylinder axis 103 with the helical curve of the electron-shading structural elements.

Claims

1. Device for impinging accelerated electrons on fluids and the inner walls of hollow bodies, comprising a cylindrical electron exit window (102) as part of a cylindrical housing (101) having a cylindrical axis (103) and enclosing an evacuable space; at least one wire-shaped, strand-shaped, rod-shaped, annular, helical, or cylindrical cathode (104a) arranged within the evacuable space and enclosed by the cylindrical electron exit window (102) and by a cylindrical control grid (104b), wherein the cylindrical control grid (104b) has a diameter smaller than the diameter of the cylindrical electron exit window (102), and wherein a first power supply device is electrically conductive between the wire-shaped, strand-shaped, rod-shaped, annular,a helical or cylindrical cathode (104a) and the cylindrical electron exit window (102) are connected, such that electrons can be emitted from the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) and accelerated radially away from the cylinder axis (103) of the cylindrical housing (101) in the direction of the cylindrical electron exit window (102), , characterized by the fact thata) a first hollow cylinder (107; 307) encloses the cylindrical electron exit window (102) and the first hollow cylinder (107; 307) and the electron exit window (102) are spaced apart from each other, so that a first annular free space (108) is formed between the first hollow cylinder (107; 307) and the electron exit window (102); b) first support elements (105) of the cylindrical control grid (104b) and second support elements (106) of the concentrically arranged cylindrical electron exit window (102) extend centrally symmetrically to each other along the respective lateral surfaces and are arranged azimuthally within equal angular segments with an angle ω.

2. Device according to claim 1, characterized by the fact that The cathode is rod-shaped or cylindrical and designed as a plasma cathode.

3. Device according to claim 1, characterized by the fact thatthe wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) is designed as a thermionic cathode.

4. Device according to claim 3, characterized by the fact that the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) is designed as a thermionic cathode heated directly by means of current flow.

5. Device according to claim 3, characterized by the fact that the cathode is cylindrical and has a wire-, strand- or rod-shaped heating element extending along the cylinder axis, wherein the cylindrical cathode can be heated by thermal conduction, thermal radiation or electron impact.

6. Device according to claim 5, characterized by the fact that one end of the cylindrical cathode is electrically connected to one end of the wire, strand or rod-shaped heating element.

7. Device according to claim 4, characterized by the fact thatThe annealing cathode comprises a ceramic rod around which a wire is wound in a helical fashion.

8. Device according to one of the preceding claims, characterized by the fact that the cylindrical control grid (104b) has a voltage difference relative to the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) of about +20 V to about +2000 V, wherein a second power supply device generates the electrical voltage potential for the cylindrical control grid (104b).

9. Device according to one of the preceding claims, characterized by the fact that the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) is only clamped at one end and contacted at the other end with an axially movable clamping piece.

10. Device according to one of the preceding claims, characterized by the fact thatthe radial position of the wire-shaped, strand-shaped, rod-shaped, ring-shaped, helical or cylindrical cathode (104a) is designed to be adjustable.

11. Device according to one of the preceding claims, characterized by the fact that a second hollow cylinder (310) surrounds the first hollow cylinder (307), so that a second annular free space is formed between the first hollow cylinder (307) and the second hollow cylinder (310).

12. Device according to claim 11, characterized by the fact that the wall of the first hollow cylinder (307) is completely closed or has openings (309).

13. Device according to one of the preceding claims, characterized by the fact thatA third hollow cylinder (512) is arranged between the cylindrical electron exit window (102) and the first hollow cylinder (107), which divides the first annular free space (108) into an inner annular free space (513) and an outer free space (514), wherein the third hollow cylinder (512) is designed as a grid or as a continuously closed or perforated film.

14. Device according to claim 13, characterized by the fact thata number of gas tubes (715) extend within the inner annular free space (513) parallel to the cylinder axis (103) of the cylindrical housing (101) and within the angular segments with the angle ω, wherein all gas tubes (715) are spaced apart from the cylinder axis (103) of the cylindrical housing (101) by an identical first dimension and from an adjacent gas tube (715) by an identical second dimension, and wherein each gas tube (715) has bores (716) or at least one slot along the longitudinal extent of the gas tube (715) on opposite wall regions, through which a gas can be introduced into the inner annular free space (513).

15. Device according to claim 14, characterized by the fact that the gas pipes (715) are attached to the third hollow cylinder (512).

16. Device according to one of claims 13 to 15, characterized by the fact thatthe first hollow cylinder (107) is electrically insulated from the third hollow cylinder (512) and a third power supply device generates an electrical differential voltage between the first hollow cylinder (107) and the third hollow cylinder (512) to ignite and maintain an electron beam-supported plasma within the outer annular free space (514).

17. Device according to one of the preceding claims, characterized by the fact that the cylinder axis (103) of the cylindrical housing (102) is aligned perpendicular to the Earth's surface or at an angle of 10° or less from the vertical.

18. Device according to one of the preceding claims, characterized by the fact thatthe first annular free space (108) or the outer annular free space (514) is covered on the inlet side in the angular ranges with the angle ω by means of mechanical apertures and that walls parallel to the cylinder axis (103) extend through the first annular free space (108) or through the outer annular free space (514), which separate the angular ranges with the angle ω from the angular ranges in between.

19. Device according to any one of claims 1 to 18, characterized by the fact that the first support elements (105) of the cylindrical control grid (104b) and the second support elements (106) of the cylindrical electron exit window (102) are formed parallel to the cylinder axis.

20. Device according to any one of claims 1 to 18, characterized by the fact thatthe first support elements (105) of the cylindrical control grid (104b) and the second support elements (106) of the electron exit window (102) run centrally symmetrically along the respective surface in the form of a helical curve.

21. Device according to one of the preceding claims, characterized by the fact that the first hollow cylinder (107) is designed as part of a hollow body.

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