Apparatus for absorbing microwaves in the form of a high frequency, high power microwave beam, comprising a bolometer load and a deflection device

Abstract

The present invention relates to an apparatus for absorbing microwaves in the form of a high-frequency, high-power microwave beam. The apparatus (50) comprises a load (20) and a deflection device (10). The load (20) is a bolometer device having a receiving cavity and comprises a hollow body (21) with the receiving cavity. The receiving cavity has an opening (25). The deflection device (10) comprises a body with a cavity, a first opening (15) of the cavity, and a second opening (16) of the cavity. The second opening (16) is connected to a transmission line (30) of a microwave beam (100). The cavity of the deflection device (10) comprises at least two focusing mirrors (11, 12) therein. The at least two focusing mirrors (11, 12) are a first focusing mirror (11) and a second focusing mirror (12).

Description

[Technical Field] 【0001】 The present invention relates to an apparatus comprising a bolometer load and a deflection device for absorbing microwaves in the form of a high frequency, high power microwave beam. [Background technology] 【0002】 In the current state of the art, fusion energy research is carried out using magnetically confined thermonuclear plasmas through several different types of devices, the most promising of which appears to be the "tokamak," as described, for example, in Angelone G. et al., "Transmission lines for ECRH experiments on FTU tokamak," Fusion Engineering, 1997, 17th IEEE / NPSS Symposium San Diego, CA, USA, 6-10 October 1997, New York, NY, USA, IEEE, US, vol. 1, 6 October 1997. 【0003】 A tokamak consists of a vacuum toroidal chamber in which a thermonuclear plasma is magnetically confined and heated to maintain the plasma temperature at the value required for the fusion process. 【0004】 Tokamaks are equipped with an external heating system to support the fusion process in a stationary state. 【0005】 The heating system includes primary ohmic heating using induced currents, which is useful for confining the plasma, and a heating system involving the injection of an intense microwave beam, which carries high power, provided by a source, for example a gyrotron, and transmitted to the reactor by a waveguide or mirror transmission line. 【0006】 This high power is injected into the plasma and heats it using a wave-particle absorption process. The source and transmission line must be operated and tuned daily on a matched load that can absorb the power of the low-reflected microwave beam. 【0007】 Low reflection refers to components of the microwave beam that are reflected off the interior walls of the load, resulting in scattered radiation that diffuses outward from the load cavity through the load opening at any angle that allows it to pass through the load opening. 【0008】 Currently, the majority of gyrotrons and loads are designed for 170 GHz, the operating frequency of the most important experimental nuclear fusion reactor, the International Thermonuclear Experimental Reactor (ITER). Currently, only a few high-power loads are available on the market. 【0009】 Examples of loads are described in Bin et al., "Advances in high power calorimetric matched loads for short pulses and CW gyrotrons," Fusion Engineering and Design, Elsevier Science Publishers, Amsterdam, NL, vol. 82, no. 5-14, 1 October 2007. 【0010】 Unfortunately, the use of loads fitted to cavities with scattering mirrors, specifically designed and tested for high power and high frequency applications, cannot be extended to very different frequencies and microwave beams with characteristics different from those designed for them. Indeed, the spot size of the Gaussian beam (evaluated at the surface of the load scattering mirror) depends on the frequency of the radiation and is one of the main input parameters for the correct design of the load. Adapting a load designed for 170 GHz to a different frequency or even multi-frequency application is not straightforward and is only possible by introducing significant modifications to the load structure. However, such design changes would result in a significant loss of know-how. This know-how is closely related to the layout currently used for 170 GHz and is the result of many years of experience and experiments also carried out by the Institute for Plasma Science and Technology (ISTP) of the Italian National Research Council (CNR). In addition, deviations in the load design would also result in a significant increase in the costs of developing new prototypes with different characteristics (dimensions, scattering mirror geometry, cooling system, etc.) that have not been tested before. This lack of know-how and rising costs will pose serious limitations to the ability to supply loads to fusion laboratories where frequencies other than 170 GHz and / or multi-frequency operation are required. 【0011】 Thumm M. et al., "Progress in the 10-MW 140-GHz System for the W7-X Stellarator," IEEE Transactions on Plasma Science, IEEE Service Center, Piscataway, NJ, US, vol. 36, no. 2, 1 April 2008, describes a system of two confocal mirrors for off-axis phase readjustment. 【0012】 Jin Jianbo et al., "A new method for synthesis of beam-shaping mirrors for off-axis incident Gaussian beams," IEEE Transactions on Plasma Science, IEEE Service Center, Piscataway, NJ, US, vol. 42, no. 5, 1 May 2014, describes a system with two converging mirrors that reshapes a beam to maintain a Gaussian distribution. Summary of the Invention [Problem to be solved by the invention] 【0013】 The object of the present invention is to design a compact microwave absorbing device that overcomes the drawbacks of the prior art, allows the use of multiple frequencies of microwave beams, and allows the use of multiple loads designed with different operating frequencies and / or lower frequencies than those used in the prior art. [Means for solving the problem] 【0014】 According to the invention, this object is achieved by a microwave absorption device as claimed in claim 1. 【0015】 A further object of the present invention is to implement a process for making a compact microwave absorbing device that overcomes the drawbacks of the prior art, thereby allowing the use of multiple frequencies of microwave beams, and that allow the use of multiple frequencies that are different operating frequencies and / or lower frequencies than those used in the prior art. 【0016】 According to the invention, this object is achieved by a method as defined in claim 14. 【0017】 Other features are provided in the dependent claims. 【0018】 The characteristics and advantages of the present invention will become more apparent from the following description, which should be understood by way of example and not by way of limitation, with reference to the accompanying schematic drawings. [Brief explanation of the drawings] 【0019】 [Figure 1] Figure 1 is a schematic diagram of a high-frequency, high-power microwave beam absorption device according to the present invention. The device comprises a bolometer load and a deflection device. The deflection device is connected to the load aperture and the microwave beam transmission line. The edges of the microwave beam are shown as dashed lines. The deflection device comprises two off-axis focusing mirrors according to a first configuration. [Figure 2] 1 is a schematic diagram of an apparatus with an alternative deflection arrangement, which comprises two off-axis focusing mirrors in a first configuration cooled by a hydraulic circuit; [Figure 3] 1 is a schematic diagram of an apparatus with an alternative deflection device, which comprises two off-axis focusing mirrors and a plane mirror according to a second configuration; [Figure 4] 1 is a schematic diagram of an apparatus with an alternative deflection device, which comprises two off-axis focusing mirrors and a plane mirror according to a third configuration; [Figure 5] FIG. 10 is a schematic diagram of a detail of the device showing the connection flange between the load and the deflection device. DETAILED DESCRIPTION OF THE INVENTION 【0020】 Referring to the aforementioned figure, there is shown an apparatus 50 for absorbing microwaves in the form of a high frequency, high power microwave beam. The apparatus 50 comprises a load 20 and a low-reflection deflection device 10 for the microwave beam. The low-reflection deflection device 10 is connected to the load 20, which is adapted for high power for a microwave beam source and transmission line. 【0021】 The microwave beam is a beam of microwaves 100 that enters the load 20 along an incident direction Z. The microwave beam 100 is infinitely divergent. The divergence depends on the frequency of the beam. Figures 1, 3, and 4 show the edges of the microwave beam with dashed lines. The divergence has been exaggerated with respect to the measurement scale to make it easier to understand. 【0022】 The microwaves of the microwave beam 100 are in the frequency range of several tens to several hundreds of GHz, that is, so-called millimeter waves. 【0023】 High power refers to the order of magnitude of several MW, ie 0.1 to 4 MW, for example 1 MW. 【0024】 High frequency refers to an order of magnitude of several tens to several hundreds of GHz, ie, 30 to 300 GHz, for example, between 1 mm and 10 mm, for example, 170 GHz. 【0025】 The deflection device 10 is part of a microwave absorption system. 【0026】 The microwave absorption system is preferably part of a plasma heating system, which is part of a nuclear fusion reactor. 【0027】 The plasma heating system comprises a source generating a high power microwave beam 100, a microwave beam 100 transmission line 30 adapted to carry the microwave beam 100, and an absorber 50 of the present invention. The absorber 50 comprises a deflector 10 connected to the microwave beam 100 transmission line 30, and a load 20. The load 20 is adapted to receive the microwave beam 100 and distribute its power to an inner surface 22 of the load 20. The load 20 is connected to the deflector 10. 【0028】 The source is preferably a gyrotron. 【0029】 The transmission line 30 for the microwave beam 100 may be, for example, an optical or quasi-optical transmission line, or a waveguide. 【0030】 The load 20 is a bolometer device having a receiving cavity, and comprises a hollow body 21 having the receiving cavity. The receiving cavity has an opening 25 for allowing the microwave beam 100 to enter the receiving cavity. Preferably, the opening 25 is arranged along the incident direction Z of the incident microwave beam 100. 【0031】 The load 20 preferably comprises a scattering mirror 23 disposed on a portion of the inner surface 22 of the receiving cavity, opposite the cavity opening 25, and aligned along the direction of incidence Z of the microwave beam 100, as shown in Figures 1 to 4. 【0032】 The divergent scattering mirror 23 reflects multiple components of the aforementioned incident microwave beam 100 at multiple angles of reflection towards the inner surface of the cavity, which is coated with an absorbing material. 【0033】 The reflected microwave beam is absorbed by the absorptive coating of the cavity. The cooling system is located outside the load 20. 【0034】 This microwave absorption process is particularly suitable when the load 20 is associated with a nuclear fusion reactor. 【0035】 Advantageously, a load 20 based on a scattering mirror 23 and a spherical vacuum cavity is one of the most compact and currently considered optimal for use in ITER, and is therefore the preferred configuration of the present invention. 【0036】 The ISTP design load 20 is preferably a hollow copper sphere with electrically formed cooling channels and an inner surface 22 coated with a partially reflective ceramic absorber deposited by plasma spraying. It is based on the insertion of a microwave beam 100 through an aperture 25 and scattering using a suitably shaped scattering mirror 23 on the opposite side. The scattered radiation is absorbed on the inner wall 22 of the cavity upon subsequent reflection. The desired uniform heat load on the load wall 22 is achieved by the precise shape of the scattering mirror 23, the deposited thickness of the coating, and multiple reflections within the cavity. For the injection of linearly polarized radiation, such as that typically emitted by a gyrotron, there are physical limitations to the possibility of achieving a uniform distribution due to differential absorption by the coating for reflections in and out of the polarization plane. 【0037】 Circularly polarized light, on the other hand, does not have this limitation. 【0038】 The incident microwave beam 100 is preferably transmitted along a transmission line by a HE 11 The beam travels in a propagation mode called 【0039】 During propagation in the load 20, the microwave beam 100 expands at an angle inversely proportional to the frequency of the radiation. The size and shape of the scattering mirror 23 is based on the size of the microwave beam 100 and the curvature of the phase front at the location of the mirror 23. 【0040】 The load 20 with a spherical cavity shown in the figure has already been used successfully at international fusion laboratories (EPFL, Lausanne, Switzerland and QST, Naka, Japan) at a frequency of, for example, 170 GHz. 【0041】 The deflection device 10 comprises a body with a cavity, a first cavity opening 15 connected to a cavity opening 25 of the load 20, and a second cavity opening 16. The second opening 16 is connected to a microwave beam 100 transmission line 30 adapted to carry the microwave beam 100 from a source to the deflection device 10. 【0042】 The deflection device 10 advantageously blocks scattered radiation resulting from the reflection of the reflected component of the microwave beam on the inner walls of the load 20 . 【0043】 The deflection device 10 reflects back any residual scattered radiation that escapes the cavity of the load 20 without interfering with the incoming microwave beam 100 . 【0044】 The cavity of the deflection device 10 comprises therein at least two converging mirrors 11, 12 arranged off-axis. 【0045】 Off-axis means that the focal axes are not on the same axis as each other, or are in the same direction but along different directions. 【0046】 The two focusing mirrors 11, 12 are placed between the incident directions of the microwave beam coming from the transmission line 30. As a result, the microwave beam leaving the transmission line is not directed directly into the cavity of the load 20, but must be deflected by at least the two focusing mirrors 11, 12 before entering the cavity of the load 20. 【0047】 The deflection device 10 is advantageously adapted to block high angle scattered radiation exiting the opening 25 of the load 20, advantageously preventing scattered radiation from returning to the source which could cause damage to the source itself. 【0048】 1 to 4, there are two focusing mirrors 11, 12, which are positioned off-axis such that the first focusing mirror 11 intercepts the incident microwave beam 100 exiting the transmission line 30 along an output direction W, and the second focusing mirror 12 intercepts the incident microwave beam 100 by deflecting it along an input direction Z. 【0049】 The focusing mirrors 11, 12 can be said to have curved surfaces that can focus, ie redirect and shape, the incident microwave beam (100) in terms of spot size and phase front curvature. 【0050】 Preferably, the focal axis of the first focusing mirror 11 is arranged along the output direction W, and the focal axis of the second focusing mirror 12 is arranged along the input direction Z. 【0051】 Preferably, the converging mirrors 11, 12 are elliptical mirrors. 【0052】 Preferably, the optical path length of the microwave beam 100 between the two mirrors 11,12 is equal to the sum of the focal lengths of the two mirrors 11,12. 【0053】 As shown in the embodiment of Figures 3 and 4, a further non-focusing mirror can be inserted along the optical path between the first two mirrors 11, 12 to change the direction to achieve a more compact layout and to obtain the advantage of changing the polarization of the microwave beam 100 to improve the power distribution inside the load 20. 【0054】 3 shows an embodiment in which a first mirror 11 focuses the microwave beam down the cavity of the deflection device 10. A third mirror 13 is arranged as a plane mirror whose geometric normal is perpendicular to the input direction Z and the output direction W, and reflects the microwave beam towards a second mirror 12, which then directs it along the input direction Z towards an opening 25 of the cavity of the load 20. 【0055】 4 shows an embodiment in which the third mirror 13 is planar and rotated at an angle relative to the focal direction of the first mirror 11. The normal to the third planar mirror 13 forms an acute angle with the input direction Z. Again, the third mirror 13 reflects the microwave beam 100 back to the second mirror 12, which then deflects it along the input direction Z toward the opening 25 of the cavity of the load 20. 【0056】 Preferably, the cavity of the deflection device 10 has metal walls and is advantageously under vacuum to avoid arcing. 【0057】 The deflection device 10 advantageously allows the use of a scattering mirror 23 and a cavity-adapted load 20, preferably with a multi-frequency absorbing coating. 【0058】 Advantageously, the deflection device 10 makes it possible to use a microwave beam 100 that contains multiple frequencies. 【0059】 Advantageously, the deflection device 10 makes it possible to use both beams containing frequencies in the range of 140 and 300 GHz, as used in the prior art, and beams containing lower frequencies, for example frequencies on the order of tens of GHz, for example between 30 and 140 GHz. 【0060】 Advantageously, deflection apparatus 10 allows for the use of multiple frequencies even when apparatus 10 is associated with an existing load 20 that is designed to optimize only one particular frequency, for example, a frequency of 170 GHz. Advantageously, deflection apparatus 10 allows for the use of multiple different frequencies without having to modify structural components of existing load 20 and therefore without having to redesign the existing load 20. 【0061】 The deflection device 10 requires additional distance from the entrance 25 of the beam 100 to the mirror 23 of the load 20. This increases the size of the incident microwave beam 100. 【0062】 The deflection device 10 can be used to reduce reflections of the load 20 and also has the advantage of providing side access for auxiliary systems such as pumping systems and arc detection safety systems, and for additional absorbing flanges. 【0063】 Thus, the deflection device 10 may house on its body a flange for connection to the transmission line 30, a flange for connection to the opening 25 of the cavity of the load 20, and one or more accesses for arc detection. The detector may be either optical fiber and / or line of sight through a vacuum window for a visible camera. 【0064】 An additional flange housed in the body of the deflection device 10 can be dedicated to the connection of a vacuum line for pumping, so as to keep the cavity of the deflection device 10 under vacuum. 【0065】 The body of the deflection device 10 can accommodate additional flanges to accommodate additional instrumentation, for example, additional microwave absorption instruments to reduce the level of scattered (dispersed) radiation power that necessarily propagates backward in the direction of the input line Z escaping the opening 25 of the load 20. 【0066】 The flange refers to the standard vacuum opening of the cavity of the deflection device 10. Preferably, the flange uses a metal gasket (e.g., metal gaskets manufactured under the brand names ConFlat® or Helicoflex®). 【0067】 Advantageously, the deflection device 10 is a separate system from the load 20 and can be easily separated, if necessary, by disconnecting the flange 35 which is connected to the entrance of the opening 25 of the load 20 and which communicates with the opening 15 of the cavity of the deflection device 10. 【0068】 5, flange 35 may preferably include a vacuum compatible bellows and / or may preferably include a rearwardly reflecting inner wall 351. Rearwardly means in the direction towards load 20. 【0069】 Additionally, scattered radiation returning into the cavity of deflection device 10 may be reflected multiple times within the cavity of deflection device 10 to form scattered radiation, some of which is partially captured by transmission line 30 on its way back to the source. 【0070】 To avoid this situation by reducing scattering of the reflected components of the microwave beam inside the cavity of the deflection device 10, the inner walls of the cavity can be covered with a coating that absorbs the scattered radiation and an integrated, preferably active, cooling circuit can be provided on the outside. 【0071】 The inner walls of the cavity of the deflection device 10 refer to the surfaces that are not occupied for the connection of external components. 【0072】 Preferably, said cavity of the deflection device 10 comprises an inner wall comprising a layer of radiation absorbing material, the absorbing material being adapted to absorb microwave radiation at a frequency compatible with microwave radiation. 【0073】 As shown in FIG. 2, a sufficient flow of water must also be injected into the circuit to cool the mirrors 11, 12. 【0074】 All mirrors 11-13 inside the deflection device 10 must preferably be actively cooled with water during the gyrotron pulse when used for long pulses and CW operation at high microwave power. To prevent the tubes of the cooling circuit 40 from coming into direct contact with the vacuum volume inside the deflection device 10 or to prevent welds from forming a boundary between the cooling means and the vacuum (usually a necessary constraint in most fusion plants), the mirrors 11-13 of the deflection device 10 are designed according to techniques already used to cool the scattering mirror 23 behind the load 20. 【0075】 This cooling technique for the mirrors 11-13, 23 consists of a hollow copper cylinder mounted on a metal-sealed vacuum flange (such as those manufactured under the brand name ConFlat®), the diameter of which depends on the diameter of the mirrors 11-13, 23. The side of the cylinder under vacuum is machined to obtain a suitable reflective surface to act as a quasi-optical mirror 11-13, 23 for the incident rays of the microwave beam 100. A gap accommodates a water injection system 40 installed to provide sufficient water cooling from the outside to extract heat from the internal reflective surface (vacuum) by efficient heat exchange through the copper thickness of the cylinder. 【0076】 More generally, as shown in Figure 2, the mirrors 11, 12, the first mirror 11 and the second mirror 12, as well as the third mirror 13, if present, consist of a cylinder 45 made of a thermally conductive material. The cylinder 45 has a hollow part (not under vacuum) that opens outwards from the deflection device 10 and is provided with an external cooling system 40, preferably active, preferably using water, adapted to exchange heat with the thermally conductive material. 【0077】 The cylinder 45 has an outer portion enclosed inside the cavity of the deflection device 10. The outer portion of the cylinder 45 has a surface that is in direct contact with the vacuum of the cavity of the deflection device 10. One surface of the outer wall of the cylinder 45 is shaped to form the mirrors 11, 12, 13. 【0078】 The conductive cylinder is preferably made of copper. 【0079】 Alternatively, the microwave absorption system may be applied in other technical fields and not necessarily in heating systems for nuclear fusion reactors. 【0080】 Alternatively, the optical path length of the microwave beam 100 between the two mirrors 11, 12 is essentially equal to the sum of the focal lengths of the two mirrors 11, 12. Essentially means a variation of about 10%. 【0081】 Advantageously, the device 50 according to the present invention having a spherical load 20 tested by ISTP for 170 GHz can also be used for multi-frequency applications and / or at a single frequency below 170 GHz, or at frequencies above 170 GHz if a lower reflection coefficient or higher power handling is required without substantial modification. 【0082】 Advantageously, positioning the load 20 off-axis with respect to the beam coming from the transmission line 30 entails that the amount of radiation that can be reflected directly back into the output direction W is very low. 【0083】 Advantageously, the relatively large volume added by installing the deflection device 10 instead of the prior art pre-load, combined with the large absorption surface of the inner walls of the deflection device 10 cavity and / or the additional cooling flange 35, results in a lower local thermal load on all heated internal parts of the deflection device 10 cavity. 【0084】 Advantageously, the accuracy of the calorimetric measurement of a system consisting of a cavity 20 with a deflection device 10 is improved, since the cooling circuits of the walls of the deflection device 10 and / or the absorbing flanges installed together with the body of the deflection device 10 are included in the balance of the power transferred to the cooling circuits, which increases the measurement accuracy. 【0085】 Advantageously, the deflection device 10 allows for a larger wall on which the flange can be placed, thereby improving the positioning of optical fibers for monitoring the arc, as well as cameras for detecting visible light from the evacuated volume, compared to the placement possible with preloads currently used in the prior art. 【0086】 Advantageously, the deflection device 10 also allows greater flexibility in terms of the placement of vacuum pumping lines. Indeed, said pumping lines can be placed in locations where the pumps are relatively protected from direct radio frequency reflections. 【0087】 Regarding the manufacture of the device 50, it is possible to define a process for manufacturing the device 50 for absorbing microwaves in the form of a high-frequency microwave beam 100. The device 50 comprises a load 20. The load is a bolometer device having a receiving cavity and comprises a hollow body 21 having the receiving cavity. The receiving cavity comprises an opening 25 for allowing the incident microwave beam 100 to enter the receiving cavity. The scattering element 23 is adapted to reflect multiple components of the incident microwave beam 100 towards multiple reflection angles by directing the multiple components of the reflected microwave beam 100 towards an inner surface 22 of the cavity. The process comprises the step of connecting a deflection device 10 for the microwave beam 100 to the opening 25 of the load 20. 【0088】 The deflection device 10 comprises a body with a cavity, a first opening 15 of the cavity connected to the opening 25 of the cavity of the load 20, and a second opening 16 of the cavity. The second opening 16 is connected to a transmission line 30 of the microwave beam 100 adapted to carry the microwave beam 100 from a source to the deflection device 10. 【0089】 The cavity of the deflection device 10 described above comprises therein at least two converging mirrors 11, 12 arranged off-axis. 【0090】 Alternatively, the load 20 may include a cavity having a shape other than a sphere, such as a cylindrical shape or other shape. 【0091】 Alternatively, and more generally, the load 20 may comprise scattering means other than the scattering mirror 23 shown in FIGS. 1 to 4, which may more generally be referred to as a scattering element 23. 【0092】 More generally, loads 20 other than those shown in FIGS. 1-4 can be used in the above-described embodiments. The main differences between different types of loads 20 lie in the scattering concept, method, and absorbing material, as well as the size and shape of the main body 21. The load developed by ISTP, such as that shown in FIGS. 1-4, is the only load with a spherical design and is a 170 GHz prototype developed at ISTP in recent years primarily for application in the testing and development of the European gyrotron for ITER. More generally, loads 20 must comply with several basic characteristics essential for their suitability in high-power systems. Because back reflections toward the transmission line along the incident direction Z can be a significant problem for the safety of gyrotron-type sources and their stable operation, as well as for the accuracy of power measurements, the load 20 must ensure a low reflectivity (on the order of 1% or less) for the safe operation of the source. Additionally, the load 20 must be spatially compact, occupying as little space as possible, allowing for flexible integration with the test facility and / or tokamak environment. Consuming a large amount of space is usually unacceptable. Installing numerous components in close proximity to the tokamak can be a major problem. Because the intense microwave beam 100 in air can create arcs—plasma points fed by microwave power returning to the source—the load 20 must be compatible for use under vacuum. Arcs have high reflectivity and hinder source use. The load 20's need for compatibility with vacuum operation means that, when connected to the reactor, all internal materials must be adequately conditioned and highly qualified to be suitable for the nuclear environment. The design of the load 20 must ensure as efficient heat exchange as possible with the external cooling water for measuring the calorific power output. This prevents even a small percentage of heat from being distributed to uncooled parts, which would otherwise be transferred to the water and measured, resulting in overheating and unwanted heat accumulation. 【0093】 Alternatively, other types of rods 20 include similar "cavity" concepts (e.g., a cylindrical cavity with or without an internal absorbing cover) but differ in cover material (e.g., titanium dioxide) and scattering method (e.g., the scattering element 23 can be understood as one or more cones or one or more rotating mirrors), as well as "lossy waveguide" concepts, in which partial absorption is achieved on the inner surface of a waveguide with properly shaped inner walls. These rods 20 are typically less compact than spherical rods and may have more reflections. 【0094】 Alternatively, and more generally, the load 20 is a bolometer device having a receiving cavity, and comprises a hollow body 21 having the receiving cavity. The receiving cavity comprises an opening 25 for allowing the microwave beam 100 to enter the receiving cavity. The load 20 comprises a scattering element 23 adapted to reflect multiple components of said incident microwave beam towards multiple reflection angles directed towards an inner surface 22 of the cavity. 【0095】 Alternatively, the converging mirrors 11, 12 may be mirrors with a cross section of another shape, including an elliptical mirror, a parabolic mirror, a hyperbolic mirror, a spherical mirror, or any cross section of a geometric cone that makes it possible to have a converging mirror. 【0096】 One mirror can have one shape and the other another, for example, first mirror 11 can be elliptical and second mirror 12 can be parabolic, or vice versa, or any of the shapes listed in the previous paragraph. 【0097】 Alternatively, the at least two focusing mirrors 11, 12 are a first focusing mirror 11 suitable for capturing the incident microwave beam 100 emerging from the transmission line 30, the focal axis of which is not necessarily aligned with the output direction W, and a second focusing mirror 12 suitable for capturing the incident microwave beam 100 by deflecting it towards the opening 25 of the load 10, the focal axis of which is not necessarily aligned with the input direction Z. 【0098】 Alternatively, the third mirror 13 may be a convex mirror and therefore non-focusing. 【0099】 Alternatively, the third mirror 13 may be a diffractive element, such as a diffraction grating. 【0100】 Alternatively, the third mirror is a polarizing mirror. 【0101】 Alternatively, said cavity of said deflection device 10 comprises within itself at least one third non-converging mirror 13 inserted along the optical path between said at least two converging mirrors 11, 12. 【0102】 Further alternatively, the cavity of the deflection device 10 comprises within itself a number of non-converging third mirrors 13 inserted along the optical path between the at least two converging mirrors 11, 12. 【0103】 Alternatively, the outer walls of the cavity of the deflection device 10 are cooled using an integrated cooling circuit, which may be active or passive. 【0104】 Alternatively, the cylinder 45 can be made of other thermally conductive materials that are capable of exchanging heat with the cooling system 40 . 【0105】 Alternatively, the entire inner surface of the cavity of the deflection device 10 is not entirely covered with absorbing material, but only a portion of the surface. 【0106】 Alternatively, the inner wall of the additional flange for the further instrumentation is also coated with the scattered radiation absorbing material. 【0107】 These additional flanges, which have an inner surface coated with an absorbent material, can be considered as at least one part of the inner wall of the cavity of the deflection device 10 . 【0108】 Alternatively, the flange may be removable. 【0109】 The invention thus conceived is susceptible to many modifications and variations within the scope of the same inventive concept, and in fact the materials used and their dimensions can be of any type depending on the technical requirements.

Claims

[Claim 1] A microwave absorption device (50) in the form of a high-frequency, high-power microwave beam (100), The apparatus (50) includes a load (20) and a deflection device (10) for a microwave beam (100), The load (20) is a bolometer device having a receiving cavity, and also, It comprises a hollow body (21) having a receiving cavity, the receiving cavity having an opening (25) for allowing an incident microwave beam (100) to enter the receiving cavity, In a microwave absorption device (50), the scattering element (23) is configured to reflect multiple components of the incident microwave beam (100) at multiple reflection angles by directing multiple components of the reflected microwave beam (100) toward the inner surface (22) of the cavity, The deflection device (10) comprises a body having a cavity, a first opening (15) of the cavity connected to the opening (25) of the load cavity (20), and a second opening (16) of the cavity, the second opening (16) being adapted to be connected to a transmission line (30) for the microwave beam (100) adapted to transport the microwave beam (100) from the source to the deflection device (10). The cavity of the deflection device (10) comprises at least two focusing mirrors (11, 12) inside itself. The at least two focusing mirrors (11, 12) are, A first focusing mirror (11) is fitted to capture the incident microwave beam (100) exiting the transmission line (30), The system includes a second focusing mirror (12) adapted to capture the incident microwave beam (100) by deflecting the incident microwave beam (100) toward the opening (25) of the load (10), A microwave absorber (50) characterized in that the length of the optical path of the microwave beam (100) between the at least two mirrors (11, 12) is substantially equal to the sum of the focal lengths of the at least two mirrors (11, 12). [Claim 2] The apparatus (50) according to claim 1, wherein the first converging mirror (11) is provided with a focal axis oriented along the output direction (W), and the second converging mirror (12) is provided with a focal axis oriented along the input direction (Z). [Claim 3] The apparatus (50) according to claim 1, wherein the cavity of the deflection device (10) comprises, within itself, at least one third mirror (13) inserted along the optical path between the at least two converging mirrors (11, 12). [Claim 4] The apparatus (50) according to claim 3, wherein at least one third mirror (13) is of the non-converging type. [Claim 5] The apparatus (50) according to claim 3, wherein at least one third mirror (13) is a planar mirror having a geometric normal that forms an acute angle with the input direction (Z). [Claim 6] The apparatus (50) according to claim 3, wherein at least one third mirror (13) is a polarizing mirror. [Claim 7] The apparatus (50) according to claim 1, wherein the cavity of the deflection device (10) is provided with a metal wall and is under vacuum. [Claim 8] The apparatus (50) according to claim 1, wherein the cavity of the deflection device (10) includes at least a portion of the inner wall having a layer of diffuse radiation absorbing material. [Claim 9] The apparatus (50) according to claim 8, wherein the outer wall of the cavity of the deflection device (10) is cooled using an integrated cooling circuit. [Claim 10] In the apparatus (50) according to claim 3, at least one of the at least two converging mirrors (11, 12) or the at least one third non-converging mirror (13) is provided with a cylinder (45) made of a thermally conductive material. The cylinder (45) is The deflection device (10) comprises a hollow internal portion that opens to the outside, and an external cooling system (40) adapted to exchange heat with the thermally conductive material, and further, The apparatus (50) comprises an outer portion enclosed within the cavity of the deflection device (10), the outer portion of the cylinder (45) having a surface that is in direct contact with the vacuum of the cavity of the deflection device (10), and the surface of the outer wall of the cylinder (45) being shaped to form at least one mirror (11, 12, 13). [Claim 11] The apparatus (50) according to claim 1, wherein the flange (35) positioned between the opening (25) of the load cavity (20) and the opening (15) of the deflection device cavity (10) preferably comprises at least one flange having a vacuum-compatible bellow and / or rearward-reflecting inner wall (351), wherein rearward means in the direction toward the load (20). [Claim 12] The apparatus (50) according to claim 1, wherein the deflection device (10) is provided with a wall on which flanges for further equipment can be installed. [Claim 13] A process for realizing a microwave absorption device (50) in the form of a high-frequency microwave beam (100), The apparatus (50) comprises a load (20), the load (20) being a bolometer apparatus having a receiving cavity, and also, It comprises a hollow body (21) having a receiving cavity, the receiving cavity having an opening (25) for allowing an incident microwave beam (100) to enter the receiving cavity, The scattering element (23) is configured to reflect multiple components of the incident microwave beam (100) at multiple reflection angles by directing multiple components of the reflected microwave beam (100) toward the inner surface (22) of the cavity, The process includes connecting a deflection device (10) for a microwave beam (100) to the opening (25) of the load (20), The deflection device (10) comprises a body having a cavity, a first opening (15) of the cavity connected to the opening (25) of the load cavity (20), and a second opening (16) of the cavity, the second opening (16) being adapted to be connected to a transmission line (30) of the microwave beam (100) adapted to transport the microwave beam (100) from the source to the deflection device (10). The cavity of the deflection device (10) comprises at least two focusing mirrors (11, 12) inside itself. The at least two focusing mirrors (11, 12) are, A first focusing mirror (11) is fitted to capture the incident microwave beam (100) exiting the transmission line (30), The system includes a second focusing mirror (12) adapted to capture the incident microwave beam (100) by deflecting the incident microwave beam (100) toward the opening (25) of the load (10), The process wherein the length of the optical path of the microwave beam (100) between the at least two mirrors (11, 12) is substantially equal to the sum of the focal lengths of the at least two mirrors (11, 12). [Claim 14] The process according to claim 13, wherein the apparatus (50) is characterized by being described in any one of claims 1 to 12.

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