A thermal coherent scattering system for measuring the ion temperature of a magnetically confined fusion device

Abstract

This invention discloses a thermally coherent scattering system for measuring the ion temperature of a magnetic confinement fusion device, relating to the field of microwave diagnostic technology for magnetic confinement fusion plasma. The system includes: a gyrotron for generating a millimeter-wave beam; and a quasi-optical matching unit installed at the output end of the gyrotron for converting the millimeter-wave beam to a TEM. 00 Pattern, and with HE 11 The mode is coupled into a corrugated circular waveguide; three corrugated circular waveguides are used, one of which is installed at the output of the quasi-optical matching unit, and adjacent corrugated circular waveguides are connected by rotatable polarizer bends, which together form a rotatable polarizer; this is a thermal coherent scattering system for measuring the ion temperature of a magnetic confinement fusion device, and the invention uses corrugated circular waveguides for transmission. The advantage of using corrugated circular waveguides for transmission is that the waveguide itself has a shielding effect, eliminating the need for additional shielding methods.

Description

Technical Field

[0001] This invention relates to the field of microwave diagnostic technology for magnetic confinement fusion plasma, specifically to a thermal coherent scattering system for measuring the ion temperature of a magnetic confinement fusion device. Background Technology

[0002] The host ion temperature is a core parameter for studying fusion reactions because it is related not only to the Lawson criterion but also to the fusion reaction rate. It is generally believed that fusion requires an ion temperature of over 10 keV, or 100 million degrees Celsius. At such high temperatures, conventional contact measurements become ineffective, so researchers have developed a series of non-contact measurements to diagnose the ion temperature.

[0003] Currently, among known technologies, thermal coherent scattering (TCS) is the method for directly diagnosing the temperature of localized host ions. The principle of TCS diagnostics is that when high-power, highly monochromatic electromagnetic waves are incident on a plasma, electrons radiate photons under the influence of the electromagnetic wave's electric field, which is called scattered light. Ions influence the movement of electrons through the Debye shielding effect, thus allowing ion information to be extracted from the TCS spectrum. In magnetic confinement fusion devices, the wavelength of the probe beam (usually selected in the millimeter-wave band) and the scattering angle θ must be designed to meet coherence conditions.

[0004] Based on this, and according to the above measurement of the main ion temperature, there are three main difficulties:

[0005] 1. Low-loss transmission of high-power microwaves. The MW-level high-power microwave sources used in thermal coherent scattering systems place extremely high demands on the power handling capacity and loss of the transmission path. Commonly used microwave lens materials, such as high-density polyethylene, may face the risk of thermal damage or breakdown under such high power.

[0006] 2. Actively adjust the polarization direction of high-power microwaves. Depending on the experimental conditions (such as magnetic field configuration and plasma density), it is necessary to excite relatively pure X-mode or O-mode in the plasma for detection. The microwaves output by the gyrotron are usually linearly polarized waves, which need to be converted into the specific polarization state required for pure O-mode or X-mode to propagate effectively in the plasma.

[0007] 3. Receiving extremely weak scattered signals. Due to the extremely small scattering cross-section of thermal coherent scattering, the scattering power is usually only on the order of nW. Detecting and extracting scattered signals in complex plasma radiation backgrounds (especially electron cyclotron radiation) is an extremely challenging problem. Summary of the Invention

[0008] The purpose of this invention is to provide a thermal coherent scattering system for measuring the ion temperature of a magnetically confined fusion device, thereby overcoming the shortcomings of the prior art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a thermal coherent scattering system for measuring the ion temperature of a magnetic confinement fusion device, comprising a magnetic confinement fusion device for generating and confining high-temperature plasma; a gyrotron for generating a millimeter-wave beam; and a quasi-optical matching unit installed at the output end of the gyrotron for converting the millimeter-wave beam to a TEM. 00 Pattern, and with HE 11 The system consists of a mode-coupled metal corrugated circular waveguide; three sections of metal corrugated circular waveguide, one of which is installed at the output of the quasi-optical matching unit, and adjacent sections are connected by rotatable polarizer bends. The two rotatable polarizer bends together form a rotatable polarizer, which is used to arbitrarily adjust the beam polarization direction; an incident mirror system, which focuses the beam output from the metal corrugated circular waveguide and adjusts the beam waist position before incident into the vacuum chamber of the magnetic confinement fusion device; a receiving mirror system, which adjusts the circumferential angle of the received beam so that the beam waist of the received beam overlaps with the beam waist of the incident beam; and a heterodyne receiver, which receives the beam focused by the mirror system and records the thermal coherent scattering signal.

[0010] Preferably, both the incident reflector system and the receiving reflector system are arranged on an external support and located on the midplane of the magnetic confinement fusion device.

[0011] Preferably, the incident reflector system includes a first ellipsoidal reflector, a first plane reflector, a second plane reflector, and a second ellipsoidal reflector arranged sequentially along the incident direction of the light beam. Both the first ellipsoidal reflector and the first plane reflector are mounted on an external support, and the distance between them is relatively fixed. The first set of reflectors, consisting of the first ellipsoidal reflector and the first plane reflector, can synchronously translate along the optical axis of the light beam on the external support. The mirror surfaces of the first ellipsoidal reflector and the first plane reflector are arranged opposite each other to expand the light beam. Both the second plane reflector and the second ellipsoidal reflector are mounted on the external support. The second ellipsoidal reflector can rotate around the optical axis to focus the light beam and adjust the direction of the light beam incident into the vacuum chamber of the magnetic confinement fusion device. When the second ellipsoidal reflector rotates around the line connecting its minor axis vertex and the focal point, the mirror surface of the second ellipsoidal reflector mates with the mirror surface of the first set of reflectors to control the focusing position of the light beam in the plasma of the magnetic confinement fusion device.

[0012] Preferably, the receiving reflector system includes a third plane reflector and a third ellipsoidal reflector. The third ellipsoidal reflector is rotatably connected to an external support, allowing it to rotate about the line connecting its minor axis vertex and the focal point to adjust the circumferential angle of the received beam.

[0013] Preferably, both ends of each rotatable polarizer bend are fixedly connected to the corresponding corrugated metal waveguide.

[0014] Preferably, each of the rotatable polarizer bends is equipped with a grooved metal reflector for adjusting the polarization direction of the beam.

[0015] Preferably, the rotatable polarizer is rotated by grooved metal mirrors within two rotatable polarizer bends to achieve continuous adjustment of the polarization direction.

[0016] Preferably, the background radiation generated by the plasma itself in the magnetic confinement fusion device is collected by a receiving mirror system and then recorded by a heterodyne receiver.

[0017] Preferably, during the gyrotron's on period, the heterodyne receiver records the superposition signal of the thermal coherent scattering signal and the plasma background radiation for a first duration; during the gyrotron's off period, the heterodyne receiver records the plasma background radiation signal for the same duration; the two signals are time-domain aligned and differentially processed to eliminate background radiation noise and extract the pure thermal coherent scattering signal.

[0018] In the above technical solution, the present invention provides a thermal coherent scattering system for measuring the ion temperature of a magnetic confinement fusion device. 1. The present invention uses a corrugated metal circular waveguide for transmission. The advantages of using a corrugated metal circular waveguide for transmission are that the waveguide itself has a shielding effect, eliminating the need for additional shielding methods; the power transmission capacity is also relatively high, capable of transmitting microwaves in the MW range.

[0019] 2. This invention employs rotatable polarizers to adjust the polarization direction. By mounting two rotatable polarizers on a commutated waveguide, the groove orientation of the two polarizers can be adjusted to achieve arbitrary polarization of high-power microwaves.

[0020] 3. This invention employs a heterodyne receiver to measure the scattered signal, verifying the scattered signal by adjusting the direction of the receiving antenna. Specifically, the receiving antenna is adjusted from a position far from the probe wave to a position gradually approaching and then moving away from the probe wave. If the received signal is observed to change from weak to strong and then back to weak, it proves that the signal originates from thermal coherent scattering. To extract the scattered signal from the high-intensity plasma background radiation, the heterodyne receiver acquires the scattered signal when the gyrotube is on and acquires a background signal of equal duration when it is off, then subtracts the two signals to extract the scattered signal. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0022] Figure 1 This is a top view of a thermal coherent scattering system provided in an embodiment of the present invention;

[0023] Figure 2 This is a front view of the incident light path of the thermal coherent scattering system provided in an embodiment of the present invention;

[0024] Figure 3 This is a front view of the receiving optical path of a thermal coherent scattering system provided in an embodiment of the present invention;

[0025] Figure 4 This is a signal flow diagram of a heterodyne receiver provided in an embodiment of the present invention;

[0026] Figure 5 This is a top view of a heterodyne receiver provided in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of MOS transistor turn-off provided in an embodiment of the present invention;

[0028] Figure 7 The MOS transistor conduction diagram is provided for an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Gyroscope; 2. Quasi-optical matching unit; 3. Corrugated circular waveguide; 4. Rotatable polarizer; 5. Incident mirror system; 5.1. First ellipsoidal mirror; 5.2. First plane mirror; 5.3. Second plane mirror; 5.4. Second ellipsoidal mirror; 6. Magnetic confinement fusion device; 7. Receiver mirror system; 7.1. Third ellipsoidal mirror; 7.2. Third plane mirror; 8. Heterodyne receiver; 8.1. Notch filter; 8.2. Bandpass filter; 8.3. RF low-noise amplifier; 8.4. Isolator; 8.5. Mixer; 8.6. Local oscillator; 8.7. Intermediate frequency low-noise amplifier; 8.8. Low-pass filter. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Please see Figure 1-7 The present invention provides a thermal coherent scattering system for measuring the ion temperature of a magnetic confinement fusion device, comprising a magnetic confinement fusion device for generating and confining high-temperature plasma, and a gyrotron 1, a quasi-optical matching unit 2, a three-section metal corrugated circular waveguide 3, a rotatable polarizer 4, an incident mirror system 5, a receiving mirror system 7, and a heterodyne receiver 8.

[0033] In the technical solution provided by the embodiments of the present invention, the above-mentioned device is based on Figure 1 The components are arranged sequentially in the middle. Furthermore, the gyrotron 1 is used to generate a millimeter-wave beam; the quasi-optical matching unit 2 is installed at the output end of the gyrotron 1 and is used to convert the millimeter-wave beam to a TEM. 00 Pattern, and with HE 11 The mode is coupled into the corrugated metal waveguide 3; one section of the corrugated metal waveguide 3 is installed at the output end of the quasi-optical matching unit 2; the incident mirror system 5 is used to focus the beam output from the corrugated metal waveguide 3 and adjust the beam waist position before incident into the vacuum chamber of the magnetic confinement fusion device 6; the receiving mirror system 7 is used to adjust the circumferential angle of the receiving beam so that the beam waist of the receiving beam overlaps with the beam waist of the incident beam; the heterodyne receiver 8 is used to receive the beam focused by the mirror system 7 and record the thermal coherent scattering signal.

[0034] It should be noted that the lengths of the three sections of corrugated metal waveguide 3 can be changed according to the specific spatial arrangement. Each of the two adjacent sections of corrugated metal waveguide 3 is provided with a rotatable polarizer 4 bend. These two rotatable polarizer 4 bends together constitute a rotatable polarizer 4 that can arbitrarily adjust the polarization direction.

[0035] Furthermore, both ends of each rotatable polarizer 4 bend are fixedly connected to the corresponding corrugated metal waveguide 3. Each rotatable polarizer 4 bend contains a grooved metal mirror for adjusting the beam polarization direction. Specifically, addressing the problem of high-power microwave polarization direction adjustment, this invention uses grooved metal mirrors to adjust the polarization direction. Two rotatable polarizer 4 bends are installed between three corrugated metal waveguides 3, and arbitrary polarization of the high-power microwave is achieved by rotating the two rotatable polarizer 4 bends and adjusting the groove direction of the two grooved metal mirrors.

[0036] In this embodiment, the rotatable polarizer 4 is rotated by grooved metal mirrors inside the bends of the two rotatable polarizer 4 to achieve continuous adjustment of the polarization direction.

[0037] The incident reflector system 5 is arranged after the last section of the corrugated metal waveguide 3, and consists of two sets of ellipsoidal reflectors and a plane reflector. Along the beam incidence direction, the components are arranged in sequence: first ellipsoidal reflector 5.1, first plane reflector 5.2, second plane reflector 5.3, and second ellipsoidal reflector 5.4. The first set consists of the first ellipsoidal reflector 5.1 and the first plane reflector 5.2, both mounted on an external support. The distance between the first ellipsoidal reflector 5.1 and the first plane reflector 5.2 is relatively fixed. The mirror surfaces of the first ellipsoidal reflector 5.1 and the first plane reflector 5.2 are arranged opposite each other to expand the beam. The second planar reflector 5.3 and the second ellipsoidal reflector 5.4 in the second group are mounted on an external support. The second ellipsoidal reflector 5.4 can rotate around the optical axis to focus the light beam and adjust the direction of the light beam incident into the vacuum chamber of the magnetic confinement fusion device 6. When the second ellipsoidal reflector 5.4 rotates around the line connecting its minor axis vertex and the focal point, the mirror surface of the second ellipsoidal reflector 5.4 mates with the mirror surface of the first group of reflectors to control the focusing position of the light beam in the plasma of the magnetic confinement fusion device 6. In addition, the first ellipsoidal reflector 5.1 and the first planar reflector 5.2 in the first group can be translated and adjusted along the optical axis as a whole to adjust the position of the beam waist. Translation and rotation work together to focus the light beam at different positions in the vacuum chamber of the confinement fusion device. The incident and receiving light paths are both arranged in the mid-plane of the magnetic confinement fusion device 6. This reduces the adjustment degrees of freedom of the incident reflector system 5.

[0038] The receiving reflector system 7 includes a third plane reflector 7.2 and a third ellipsoidal reflector 7.1. The third ellipsoidal reflector 7.1 is rotatably connected to an external support, so that the third ellipsoidal reflector 7.1 can rotate about the line connecting its minor axis vertex and the focal point to adjust the circumferential angle of the received beam.

[0039] In this embodiment, the joint adjustment of the incident reflector system 5 and the receiving reflector system 7 can realize the measurement of the main ion temperature at any location within the plasma.

[0040] Among them, the background radiation generated by the plasma itself in the magnetic confinement fusion device 6 is collected by the receiving mirror system 7 and then recorded by the heterodyne receiver 8.

[0041] During the period when gyrotube 1 is open, the heterodyne receiver 8 records the superposition signal of thermal coherent scattering signal and plasma background radiation for a first duration; during the period when gyrotube 1 is closed, the heterodyne receiver 8 records the plasma background radiation signal for the same duration; the two signals are time-domain aligned and differentially processed to eliminate background radiation noise and extract the pure thermal coherent scattering signal.

[0042] Specifically, the millimeter-wave beam generated by gyrotron 1 is transformed into high-purity TEM light after passing through quasi-optical matching unit 2. 00 Pattern, and then HE 11 The mode is coupled into the corrugated circular waveguide 3, and after being adjusted to the required polarization direction by the rotatable polarizer 4, it is recoupled into a TEM at the waveguide outlet. 00 The plasma, after being focused and its waist position adjusted by the incident reflector system 5, is incident into the vacuum chamber of the magnetic confinement fusion device 6, where it undergoes thermal coherent scattering. The thermal coherent scattering signal generated within the scattering volume propagates outside the magnetic confinement fusion device 6 and is then focused by the receiving reflector system 7 and coupled into the heterodyne receiver 8, which records the thermal coherent scattering signal. During the period when the gyrotube 1 is closed, the background radiation generated by the plasma itself in the magnetic confinement fusion device 6 is collected by the receiving reflector system 7 and recorded by the heterodyne receiver 8 for the same duration. By subtracting the two recorded signals, the thermal coherent scattering signal can be extracted from the plasma background radiation. Furthermore, the extracted thermal coherent scattering signal can be used to extract parameters such as the main ion temperature using algorithms such as least squares fitting.

[0043] It should be noted that in the thermal coherent scattering diagnostic system, the output mode of the emission source gyrotron 1 is TEM. 00 Model, we need to convert this microwave energy into HE 11 The mode propagates in a corrugated circular waveguide, and a mirror antenna is used at the waveguide end near the plasma boundary to deliver microwave energy into the plasma. Specifically:

[0044] HE 11 Model field structure ( poloidal electric field and The circumferential electric field can be formally represented as:

[0045]

[0046] in, It is a Bessel function, where r is the distance from the point to the waveguide axis, and a is the inner radius of the waveguide. The HE function in polar coordinates... 11 Transformation of the mode field components to Cartesian coordinates (i.e., the electric field in the horizontal direction) and vertical electric field ),have

[0047]

[0048] Expand the 0th-order Bessel function using a higher-order Laguerre-Gaussian function, i.e.

[0049]

[0050] in,

[0051]

[0052] It is a p-order Laguerre-Gaussian function. These are the projection coefficients of the 0th-order Bessel function onto an orthogonal basis, where... (x) is a p-order Laguerre polynomial, where x is a variable, and x = exp(y) describes the field amplitude distribution within the cross-section, which gradually decays from the center outwards according to a Gaussian function distribution. Here, y is a variable, and y = .

[0053] Furthermore, the Laguerre-Gaussian function is an orthonormal basis that satisfies:

[0054]

[0055]

[0056] Therefore, we can obtain:

[0057]

[0058] in,

[0059]

[0060] Among them, the above These are intermediate variables, the purpose of which is to solve... The integral equation is transformed into an integral equation with an analytical expression.

[0061] here It is a Gaussian model (TEM) 00 The waist radius of the Gaussian modulus. Since we are only interested in the Gaussian modulus, we only need to find its maximum value:

[0062]

[0063] Make Take the maximum value ,for =0.6435a, at this time =0.911a. HE 11 Total power of the module :

[0064]

[0065] Maximum total power contained in Gaussian mode for:

[0066]

[0067] The maximum power ratio contained in the Gaussian mode is :

[0068]

[0069] This shows that the Gorski model and HE 11 The maximum efficiency of mode coupling is 98%.

[0070] Based on the above, it is known that TEM 00 A mode is a wave mode that propagates in free space, HE 11 TEM 00 The wave mode propagating in the corrugated metal circular waveguide 3.

[0071] In this embodiment of the invention, to address the low-loss transmission problem of high-power microwaves, a corrugated metal circular waveguide 3 is used for transmission. The advantages of using a corrugated metal circular waveguide 3 for transmission are that the waveguide itself provides shielding, eliminating the need for additional shielding methods; the power transmission capacity is also relatively high, capable of transmitting microwaves in the MW range. Specifically, to minimize the diffraction effect (generating higher-order modes and increasing loss) during microwave transmission within the corrugated metal circular waveguide 3, the groove period should satisfy the following:

[0072] Where λ is the transmission wavelength. To achieve minimum ohmic loss, the groove depth h should be selected as...

[0073] Furthermore, the duty cycle of the groove should be selected as 0.7 to reduce machining difficulty and ohmic loss.

[0074] To address the problem of measuring and identifying thermally coherent scattering signals, this invention employs a heterodyne receiver 8 to measure the scattering signal. Before the formal experiment, the scattering signal is verified by adjusting the direction of the receiving antenna. Specifically, the direction of the receiving antenna is adjusted so that it gradually approaches the probe wave from a position far away from it, and then moves away from it. If the received signal is observed to change from weak to strong and then back to weak, it proves that the signal originates from thermally coherent scattering. To extract the scattering signal from the high-intensity plasma background radiation, the heterodyne receiver 8 collects the scattering signal when the gyrotube 1 is on and collects a background signal of equal duration when it is off. The difference between the two signals is then used to extract the scattering signal.

[0075] In a preferred embodiment of the present invention, the heterodyne receiver 8 mainly includes a notch filter 8.1, a bandpass filter 8.2, an RF low-noise amplifier 8.3, an isolator 8.4, a mixer 8.5, a local oscillator 8.6, an intermediate frequency low-noise amplifier 8.7, and a low-pass filter 8.8.

[0076] In this invention, a MOSFET is used to control the power supply of the RF low-noise amplifier 8.3. Based on this, it should be noted that, in conjunction with... Figure 6-7As shown, the power supply process of the control circuit after the N-channel MOSFET receives an external trigger signal is as follows: when its gate voltage is lower than the threshold voltage, the MOSFET is in the off state, and a high impedance state is presented between the source and the drain; when the gate voltage is higher than the threshold voltage, the MOSFET is turned on, and a low impedance path is formed between the source and the drain.

[0077] Specifically, during the rising edge of the high-voltage power supply of gyrotron 1, no trigger signal is applied to the gate of the MOSFET, the MOSFET is turned off, and the RF low-noise amplifier 8.3 does not work due to power failure. After gyrotron 1 enters a stable operating state, a trigger signal is applied to the gate of the MOSFET, the MOSFET is turned on, and the RF low-noise amplifier 8.3 is powered on and begins to work. This scheme can achieve a switching time of less than 1μs, effectively avoiding the influence of rising edge noise modes on the RF low-noise amplifier 8.3 and protecting the heterodyne receiver 8.

[0078] The radio frequency (RF) signal, after being received by the antenna, first enters a notch filter 8.1. Strong spurious signals are significantly attenuated by the notch filter 8.1, thus filtering out spurious interference and obtaining a relatively clean scattered signal. Next, the pre-filtered RF signal passes through a bandpass filter 8.2 before reaching the RF low-noise amplifier 8.3. The switching state of the RF low-noise amplifier 8.3 is controlled by an external trigger signal: during the rising edge of the high-voltage power supply to gyrotron 1, the external trigger signal turns off the MOSFET, and the RF low-noise amplifier 8.3 is not working due to power failure; during the stable operation of gyrotron 1, the external trigger signal turns on the MOSFET, and the RF low-noise amplifier 8.3 is powered on and begins to operate, amplifying the input RF signal. To ensure that the RF signal passes through the RF low-noise amplifier 8.3 unidirectionally, an isolator 8.4 is added after the RF low-noise amplifier 8.3. The isolator 8.4 transmits the signal only in one direction, while providing high isolation (signal attenuation) in the opposite direction.

[0079] Furthermore, in order to acquire the scattered signal, the radio frequency (RF) signal needs to be down-mixed. Therefore, the RF signal after passing through isolator 8.4 is down-mixed with the local oscillator signal generated by local oscillator 8.6 in mixer 8.5 to generate an intermediate frequency (IF) signal. This IF signal is then further amplified by IF low-noise amplifier 8.7, and finally filtered by low-pass filter 8.8 before being output for data acquisition by the data acquisition system.

[0080] Based on the above preferred embodiments, it can be seen that the present invention adopts a signal processing flow of low-noise amplification followed by mixing. This scheme can significantly reduce electronic noise, thereby helping to improve the sensitivity of the heterodyne receiver 8.

[0081] Meanwhile, in this invention, a narrowband notch filter 8.1 with a high attenuation coefficient is added before the RF low-noise amplifier 8.3. The RF low-noise amplifier 8.3 is used to amplify the received RF signal, and it has a maximum receiveable power. Exceeding this power will cause the RF low-noise amplifier 8.3 to saturate or even be damaged. Therefore, it is necessary to attenuate stray signals before they enter the RF low-noise amplifier 8.3.

[0082] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A thermally coherent scattering system for measuring the ion temperature in a magnetically confined fusion device, characterized in that, include: Magnetic confinement fusion device, used to generate and confine high-temperature plasma; A gyrotube, used to generate millimeter-wave beams; The three-section corrugated circular waveguide has two adjacent sections connected by a rotatable polarizer bend. The two rotatable polarizer bends together form a rotatable polarizer, which is used to adjust the polarization direction of the beam arbitrarily. A quasi-optical matching unit, mounted at the output of the gyrotube, is used to convert the millimeter-wave beam to the TEM. 00 The pattern is used to couple millimeter-wave beams into a corrugated metal circular waveguide; An incident mirror system is used to focus the beam output from the corrugated metal waveguide and adjust the beam waist position before it is incident into the vacuum chamber of the magnetic confinement fusion device. A receiving reflector system is used to adjust the circumferential angle of the received beam so that the waist of the received beam overlaps with the waist of the incident beam. A heterodyne receiver is used to receive a beam of light focused and coupled by a mirror system and to record the thermally coherent scattered signal.

2. The thermal coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 1, characterized in that, Both the incident reflector system and the receiving reflector system are arranged on an external support and located on the midplane of the magnetic confinement fusion device.

3. A thermally coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 1, characterized in that, The incident mirror system includes a first ellipsoidal mirror, a first plane mirror, a second plane mirror, and a second ellipsoidal mirror arranged sequentially along the incident direction of the light beam. Both the first ellipsoidal reflector and the first plane reflector are mounted on an external support, and the distance between the first ellipsoidal reflector and the first plane reflector is relatively fixed. The first set of reflectors formed by the first ellipsoidal reflector and the first plane reflector can be synchronously translated along the optical axis of the beam on the external support. The mirror surfaces of the first ellipsoidal reflector and the first plane reflector are arranged opposite to each other to expand the beam. The second planar reflector is mounted on an external support. The second ellipsoidal reflector is rotatably connected to the magnetic confinement fusion device around the optical axis to focus the beam and adjust the direction of the beam incident into the vacuum chamber of the magnetic confinement fusion device. When the second ellipsoidal reflector rotates around the line connecting its minor axis vertex and the focal point, it cooperates with the translation of the first set of reflectors to control the focusing position of the beam in the plasma of the magnetic confinement fusion device.

4. A thermally coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 3, characterized in that, The receiving reflector system includes a third plane reflector and a third ellipsoidal reflector. The third ellipsoidal reflector is rotatably connected to an external support, allowing it to rotate about the line connecting its minor axis vertex and the focal point to adjust the circumferential angle of the received beam.

5. A thermally coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 1, characterized in that, Both ends of each rotatable polarizer bend are fixedly connected to the corresponding corrugated metal waveguide.

6. A thermal coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 5, characterized in that, Each of the rotatable polarizer bends is equipped with a grooved metal reflector for adjusting the polarization direction of the beam.

7. A thermal coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 6, characterized in that, The rotatable polarizer rotates through grooved metal mirrors within two rotatable polarizer bends to achieve continuous adjustment of the polarization direction.

8. A thermally coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 1, characterized in that, The background radiation generated by the plasma itself in the magnetic confinement fusion device is collected by the receiving mirror system and then recorded by the heterodyne receiver.

9. A thermally coherent scattering system for measuring the ion temperature of a magnetically confined fusion device according to claim 8, characterized in that, During the gyrotron's operation, the heterodyne receiver records the superposition of the thermal coherent scattering signal and the plasma background radiation for the first duration. During the period when the gyrotube is closed, the heterodyne receiver records the plasma background radiation signal for the same duration; The two signals are time-domain aligned and differentially processed to eliminate background radiation noise and extract pure thermal coherent scattering signals.

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