Dual-channel, reverse-phase output, tunable radio frequency spiral resonator and methods of using the same

Abstract

The application provides a double-channel reverse-phase output adjustable radio frequency spiral resonator and a use method thereof. The resonator comprises an electromagnetic shielding shell, a primary coil, a secondary coil with adjustable pitch and an adjusting mechanism. The primary coil is arranged on one side of the inside of the electromagnetic shielding shell along the axial direction of the electromagnetic shielding shell, and the two ends of the primary coil are led out of the electromagnetic shielding shell as the input end of the resonator to be connected with an external radio frequency signal. The secondary coil is arranged in the inside of the electromagnetic shielding shell along the axial direction of the electromagnetic shielding shell. The two ends of the secondary coil are led out of the electromagnetic shielding shell as the first output end and the second output end of the resonator. Through electromagnetic coupling with the primary coil, the radio frequency signals with the same frequency, equal amplitude and 180-degree phase difference are output at the first output end and the second output end. The adjusting mechanism is used for changing the pitch of the secondary coil to continuously change the inductance of the secondary coil and continuously adjust the resonant frequency of the resonator.

Description

Technical Field

[0001] This invention belongs to the field of ion trap radio frequency system technology, and in particular to a dual-channel inverted output adjustable radio frequency spiral resonator and its usage method. Specifically, it relates to an adjustable resonant frequency radio frequency spiral resonator for trapping ions in an ion trap, which can be widely used in quantum information processing, ion trap mass spectrometry analysis, atomic frequency standards and precision spectrometry. Background Technology

[0002] The helical resonator is a core component of an ion trap radio frequency system. The ability of an ion trap to confine ions strongly depends on a suitable radio frequency potential; different ions require drastically different trapping frequencies. For example, Ca... + The optimal trapping frequency for ions is 3-6 MHz, while Be + Ions require 9-14 MHz. Furthermore, the potential well depth D of the ion trap is related to the radio frequency voltage U. rf Satisfying D = QqU rf / 8, Higher RF voltage helps to form a deeper potential well, improving ion trapping lifetime and stability.

[0003] A typical ion trap RF system consists of: an arbitrary waveform generator → a power amplifier → a spiral resonator → an AC / DC coupling circuit → an ion trap. Specifically, the arbitrary waveform generator is connected to the power amplifier via a BNC-to-SMA cable, the power amplifier is connected to the resonator via an SMA-to-BNC cable, the resonator is connected to the AC / DC coupling circuit via a BNC cable, the static DC power supply is connected to the AC / DC coupling circuit via a wire, and the AC / DC coupling circuit is connected to the ion trap via vacuum enameled wire. During operation, the arbitrary waveform generator produces a sinusoidal RF potential (e.g., 6 MHz frequency, peak-to-peak value 0.5-1 V), which is amplified by the power amplifier (40 dB gain) to a peak-to-peak value of 50-100 V. Further amplification by the resonator brings the peak-to-peak value to 500-1000 V, while maintaining a constant frequency. The static DC power supply generates an electrostatic potential (typically less than 5 V), which is coupled to the RF potential via the AC / DC coupling circuit, ultimately providing the trapping potential for the ion trap. The radio frequency potential amplitude required for trapping ions is typically in the hundreds or even thousands of volts, while the amplitude of a high-frequency sinusoidal signal output by an arbitrary waveform generator is usually below 1 volt. A power amplifier (40 dB gain) amplifies the potential by about 100 times. Only by combining a spiral resonator and a power amplifier can the potential provided by the signal generator be amplified by more than 1000 times to meet the potential amplitude requirements of trapped ions. Therefore, the spiral resonator is crucial for ion trap radio frequency systems.

[0004] However, existing helical resonators typically have a fixed resonant frequency, which severely limits the selection of ion species that can be studied, hindering the flexibility of experimental schemes and the potential for system upgrades. For example, when researchers need to obtain Ca... + Switching to Be ion experiments + In ion experiments, it is often necessary to replace the entire spiral resonator, which is costly and cumbersome.

[0005] It is important to note that while general-purpose variable inductors exist on the market, their core characteristics are: discrete structure, metal lead screw, slider with built-in nut, and no scene-specific design, which is fundamentally different from the integrated and specialized design of this invention. General-purpose variable inductors are merely independent passive components, requiring extensive external matching circuitry for use, and introducing metal conductor losses during adjustment, resulting in a Q value typically below 100. Ion trap RF systems have stringent requirements for resonator Q value (>200), frequency stability (±0.02MHz), switching speed (seconds), and electromagnetic compatibility, which general-purpose variable inductors cannot meet.

[0006] Among existing related technical solutions, Siverns et al. systematically studied the design method of helical resonators for ion traps (e.g., "On the application of radio frequency voltages to ion traps via helical resonators", published in Appl Phys B (2012)). This method proposed an LCR lumped parameter model for frequency prediction, but did not solve the problem of resonator frequency tunability. Some existing helical resonators achieve tuning by adjusting the equivalent capacitance through a metal screw inserted into the coil. However, this method introduces a "short-circuit turn effect" over a wide tuning range, resulting in a significant decrease in the quality factor Q (typically 30%-50%). Furthermore, the metal screw generates significant heat due to eddy current effects, limiting the resonator's power handling capability. In addition, some solutions change the inductance by switching the number of coil turns using taps. However, this method can only achieve discrete adjustment and cannot achieve continuous tuning. Moreover, the circuit must be disconnected during the switching process, making operation inconvenient.

[0007] To address this, this invention proposes a novel radio frequency spiral resonator that adjusts the inductance by continuously changing the pitch of the secondary coil through a precision thread mechanism, thereby achieving a wide range of continuously adjustable resonant frequencies. Simultaneously, this invention uses RENY (glass fiber reinforced polyamide MXD6) as the material for the frame and adjustment mechanism. This material is fully insulating, with no metal parts entering the coil, fundamentally avoiding short-circuit turn effects and eddy current losses, allowing the resonator to maintain a high Q value across the entire tuning range. Furthermore, RENY material has strength approaching that of metal while weighing only 1 / 5 that of iron, and can support precision thread machining as small as 0.25 mm, combining the advantages of lightweight and high precision. RENY material also possesses excellent heat resistance (its heat distortion temperature is much higher than the actual operating temperature rise of the resonator), maintaining dimensional stability even under high-power continuous operation conditions, ensuring long-term reliability of adjustment accuracy. Summary of the Invention

[0008] The purpose of this invention is to propose a dual-channel inverting output adjustable radio frequency spiral resonator and its usage method. Addressing the technical problems of fixed frequency or tuning methods in existing spiral resonators, this invention uses a precision thread mechanism to continuously change the pitch of the secondary coil to adjust the inductance, thereby achieving a wide range of continuously adjustable resonant frequencies. Furthermore, it can adapt to the trapping frequency requirements of different ion species (covering a range of 5-10 MHz) while maintaining a high quality factor, thus improving the flexibility and versatility of ion trap experimental systems.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A dual-channel inverting output adjustable radio frequency spiral resonator includes an electromagnetic shielding housing, a primary coil 8, a pitch-adjustable secondary coil 7, and an adjustment mechanism.

[0011] The primary coil 8 is arranged along the axial direction of the electromagnetic shielding shell on one side inside the electromagnetic shielding shell, and the two ends of the primary coil 8 are led out of the electromagnetic shielding shell as the resonator input terminal 15 for connecting external radio frequency signals.

[0012] The secondary coil 7 is arranged inside the electromagnetic shielding shell along the axial direction of the electromagnetic shielding shell; the two ends of the secondary coil 7 are led out of the electromagnetic shielding shell and serve as the first output terminal 13 and the second output terminal 14 of the resonator, respectively. Through electromagnetic coupling with the primary coil 8, the first output terminal 13 and the second output terminal 14 output radio frequency signals with the same frequency, equal amplitude and 180° phase difference.

[0013] The adjustment mechanism is used to change the pitch of the secondary coil 7, so as to realize the continuous change of the inductance of the secondary coil 7 and the continuous adjustment of the resonant frequency of the resonator.

[0014] Preferably, the electromagnetic shielding shell includes a shielding cylinder 3, and a shielding top cover 2 and a shielding bottom cover 10 disposed at the upper and lower ends of the shielding cylinder 3 to enclose and form an internal shielding cavity;

[0015] The shielding bottom cover 10 is slidably sleeved on the end of the shielding cylinder 3. The primary coil 8 is fixed to the inner side of the shielding bottom cover 10 and moves along the axial direction of the electromagnetic shielding shell with the shielding bottom cover 10 to adjust the axial distance between it and the secondary coil 7, thereby changing the mutual inductance coupling strength and optimizing the quality factor Q value.

[0016] Preferably, the adjustment mechanism includes a fixed frame 9, a sliding frame 6, a threaded rod 4, and a stepper motor 1;

[0017] The threaded rod 4 is arranged along the axial direction of the electromagnetic shielding shell inside the electromagnetic shielding shell, and one end of the threaded rod 4 extends out of the shielding top cover 2 and is connected to the stepper motor 1 for transmission.

[0018] The fixed frame 9 and the sliding frame 6 are located inside the shielding cylinder 3 and are arranged along the axial direction of the electromagnetic shielding shell; the fixed frame 9 is fixedly connected to the shielding cylinder 3 and is used to fix one end of the secondary coil 7.

[0019] The sliding frame 6 is located on the side of the fixed frame 9 near the shielding top cover 2, and is used to fix the other end of the secondary coil 7; the sliding frame 6 is sleeved on the threaded rod 4 and threadedly engaged with the threaded rod 4, and the sliding frame 6 slides with the guide rail 5 fixed to the inner wall of the shielding cylinder 3 through the guide groove on the outer periphery.

[0020] The stepper motor 1 drives the threaded rod 4 to rotate, and through the threaded engagement, it drives the sliding frame 6 to move along the axial direction of the electromagnetic shielding shell, thereby changing the pitch of the secondary coil 7.

[0021] Preferably, the fixed frame 9 has a through hole in the middle for the primary coil 8 to pass through, so that the primary coil 8 is located inside the secondary coil 7; the primary coil 8 and the secondary coil 7 are arranged coaxially, and the diameter of the primary coil 8 is smaller than the diameter of the secondary coil 7.

[0022] Preferably, the fixed frame 9 and the sliding frame 6 are respectively provided with coil grooves that match the shape of the secondary coil 7, and the two ends of the secondary coil 7 are respectively embedded in the coil grooves of the fixed frame 9 and the sliding frame 6 and fixed by coil clamping plates.

[0023] Preferably, a bearing is provided in the central shaft hole of the shielding top cover 2, and the upper end of the threaded rod 4 passes through the inner hole of the bearing and is axially limited by the E-type retaining ring, so that the threaded rod 4 can only rotate around its own axis and its axial position is fixed.

[0024] The portion of the threaded rod 4 extending out of the shielding top cover 2 is fitted with a brass shielding cover 16 that is in communication with the shielding top cover 2. The brass shielding cover 16 extends along the threaded rod 4 toward the motor and has a pre-reserved sealing ring insulation gap near the flexible coupling 12.

[0025] The output shaft of the stepper motor 1 and the threaded rod 4 are connected by a flexible coupling 12. The flexible coupling 12 adopts a double-set screw clamping structure to realize the switching of manual drive mode: loosening the set screw on the motor side disengages the flexible coupling 12 from the motor output shaft, and the threaded rod 4 is driven to rotate by manually rotating the flexible coupling 12.

[0026] Preferably, the stepper motor 1 is fixed to the outside of the shielding top cover 2 by a motor bracket 11; an insulating pad is provided between the motor bracket 11 and the shielding top cover 2, and a conductive spring is provided between the motor bracket 11 and the electromagnetic shielding shell to ensure the continuity of electromagnetic shielding; the lead wire of the stepper motor 1 passes through the ferrite magnetic ring and is connected to the driver to avoid driving noise coupling to the secondary coil 7.

[0027] Preferably, the fixed frame 9, sliding frame 6, threaded rod 4, guide rail 5, coil pressure plate and motor bracket 11 are all made of glass fiber reinforced polyamide MXD6; the surface of the secondary coil 7, except for the electrical connection sections reserved at both ends, is coated with an insulating paint layer to ensure inter-turn insulation.

[0028] A method for using a dual-channel inverting output adjustable radio frequency spiral resonator, characterized in that the resonator's frequency self-calibration method includes:

[0029] Connect the first output terminal 13 and the second output terminal 14 of the resonator to the adjacent electrodes of the ion trap;

[0030] The host computer is connected to the arbitrary waveform generator, the driver of the stepper motor 1, and the photodetector, respectively. The photodetector is used to collect the fluorescence signal of ions in the ion trap.

[0031] The host computer controls the stepper motor 1 to drive the threaded rod 4 to rotate, thereby changing the pitch τ of the secondary coil 7, and controls the arbitrary waveform generator to output a sine signal with a scanning frequency to the resonator input terminal 15.

[0032] The intensity of ion fluorescence in the ion trap is collected by a photodetector, a mapping curve between the pitch τ and the fluorescence intensity is established, and the target pitch τ* and resonant frequency f0 corresponding to the fluorescence peak are locked.

[0033] Establish a mapping table between ion species, target pitch τ*, and resonant frequency f0; when switching ion species, call the corresponding target pitch τ* value in the mapping table to control stepper motor 1 to position to the target pitch;

[0034] In establishing the mapping curve between pitch τ and fluorescence intensity, a coarse scan is first performed within the pitch adjustment range of secondary coil 7 with a first step length, and then a fine scan is performed near the target pitch obtained by the coarse scan with a second step length smaller than the first step length to achieve calibration of the target pitch.

[0035] Preferably, it also includes a frequency dynamic tracking step:

[0036] The output voltage amplitude of the secondary coil 7 is monitored in real time. When the voltage amplitude drops below the preset threshold, the rotation angle of the stepper motor 1 is finely adjusted by the host computer until the output voltage amplitude recovers.

[0037] The linear expansion coefficient of the thread rod material is obtained in advance, and the operating temperature of the resonator is collected in real time by the host computer. The rotation angle of the thread rod is automatically adjusted according to the temperature change to compensate for the pitch change caused by thermal expansion.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. Continuously adjustable frequency: The resonant frequency can be continuously changed in the range of 5-10 MHz by rotating the precision threaded rod, which can adapt to the trapping requirements of different ion species without changing the hardware.

[0040] 2. Dual-channel inverted output suppresses common-mode noise: The radio frequency potentials output from the two output terminals have the same frequency, equal amplitude, and opposite phase (180° out of phase), forming a balanced output structure, which can effectively suppress common-mode interference and improve the stability of ion trap confinement.

[0041] 3. Maintaining a high Q value: Unlike the solution of tuning the capacitor by metal screws, which significantly reduces the Q value within the tuning range due to the "short-circuit turn effect" (typically by 30% to 50%), this invention adjusts the inductance by changing the coil pitch. The adjustment mechanism (RENY frame + threaded rod) is a fully insulated structure, which does not introduce additional eddy current loss mechanism. The Q value can be maintained above 200 within the entire tuning range, which is significantly better than the existing solution.

[0042] 4. Q value can be further optimized: The primary coil is fixed to the shielding top cover. By adjusting the axial position of the top cover (the adjustment range is up to 20 cm), the relative distance between the primary coil and the secondary coil can be changed, the mutual inductance coupling strength can be adjusted, and the quality factor Q value can be further optimized.

[0043] 5. Coaxial tight coupling structure improves efficiency: The primary coil and secondary coil are arranged coaxially, and the primary coil is located inside the secondary coil. The magnetic flux coupling efficiency is high and the energy transmission loss is small, which is conducive to obtaining a higher output RF voltage at a lower input power.

[0044] 6. Significant material advantages: RENY material combines high strength (close to metal), low density (about 1 / 5 of iron), excellent insulation properties, and good temperature resistance (heat distortion temperature is much higher than the actual operating temperature rise of the resonator), which ensures that the skeleton and threaded rod have both structural rigidity and precision machining accuracy (supporting 0.25 mm pitch), while avoiding eddy current loss and heat generation problems of metal parts.

[0045] 7. Fully electric control: The secondary coil pitch adjustment is driven by a 28BYJ-48 stepper motor, with an adjustment accuracy better than 0.002 MHz, which facilitates automated control by the host computer and remote experiments.

[0046] 8. Enhanced system flexibility: A single resonator can meet the needs of various ion experiments, reducing system hardware costs and switching time, and enhancing the flexibility of experimental schemes and the potential for system upgrades.

[0047] 9. Triple-function integrated sliding frame: The sliding frame integrates the functions of external nut, coil carrier and guide limit, with an adjustment cycle life of >100,000 times (engineering estimate based on the fatigue resistance characteristics of RENY material and low stress working conditions of the structure), and an inductance adjustment linearity error of <1%, which is far superior to general variable inductors (life <10,000 times, linearity error >5%). Attached Figure Description

[0048] Figure 1 This is a cross-sectional view of the overall structure of the dual-channel inverted output adjustable radio frequency spiral resonator of the present invention (there is an M3 set screw at each end of the elastic coupling 12; the upper set screw locks the motor output shaft, and the lower set screw locks the upper optical shaft of the threaded rod, which is not separately labeled in the figure).

[0049] Figure 2 This is a schematic diagram of the secondary coil of the present invention under different compression states;

[0050] Figure 3 This is a schematic diagram of the fixing method between the secondary coil and the frame of the present invention (taking the fixing of the frame as an example).

[0051] Figure 4 This is the overall connection circuit diagram of the present invention in the ion trap radio frequency system;

[0052] Figure 5 This is a schematic diagram of the overall architecture of the ion trap radio frequency system of the present invention;

[0053] Figure 6 This is a schematic diagram of the thin-walled brass shielding cover of the present invention.

[0054] In the picture:

[0055] 1—Stepper motor (28BYJ-48 type); 2—Shielding top cover; 3—Shielding cylinder (copper, 2 mm thick); 4—Threaded rod (RENY material, pitch 0.25 mm); 5—Guide rail (RENY material); 6—Sliding frame (movable end, RENY frame); 7—Secondary coil (annealed copper wire, φ2 mm, surface coated with insulating varnish); 8—Primary coil (annealed copper wire, φ1 mm); 9—Fixed frame (fixed end, RENY frame); 10—Shielding bottom cover; 11—Motor bracket (RENY material); 12—Flexible coupling (LK1-15-0505M type miniature flexible coupling); 13—First output end (BNC interface); 14—Second output end (BNC interface); 15—Input end (BNC interface); 16—Brass shielding cover. Detailed Implementation

[0056] The following is in conjunction with the appendix Figure 1-6 The technical solution of the present invention will be described in detail below.

[0057] This invention proposes a dual-channel inverting output adjustable radio frequency spiral resonator, as detailed below:

[0058] 1. Basic structural components

[0059] Electromagnetic shielding housing: comprising a shielding cylinder 3, a shielding top cover 2, and a shielding bottom cover 10, made of copper, 2 mm thick, cylindrical in shape, used to shield external electromagnetic interference and constrain the electromagnetic field distribution inside the resonator; the inner diameter of the shielding cylinder D = 80 mm, and the height B = 140 mm. The shielding top cover 2 and the shielding bottom cover 10 are respectively installed at both ends of the shielding cylinder 3, and are fixedly connected to the shielding cylinder 3 by screws. Conductive springs are added at the joints to ensure the continuity of electromagnetic shielding. Two symmetrical guide rails 5 are fixed axially on the inner side of the shielding cylinder 3, extending axially to ensure that the sliding frame 6 can only move axially and cannot rotate.

[0060] Secondary coil 7 (spiral coil): Wound with annealed copper wire of 2 mm diameter, with N=10 turns and coil diameter d=50 mm. Except for 10 mm reserved at each end for electrical connection, all coil surfaces are coated with a layer of insulating varnish to ensure inter-turn insulation.

[0061] Primary coil 8: Located inside the electromagnetic shielding housing, it is electromagnetically coupled to secondary coil 7. It is wound with annealed copper wire of 1 mm diameter, with 2 turns, and a coil diameter of approximately 20 mm. Primary coil 8 is fixed inside the shielding base cover 10 and moves axially with the base cover 10 to adjust the axial distance between it and secondary coil 7, thereby changing the mutual inductance coupling strength and optimizing the quality factor (Q). By adjusting the axial position of the shielding base cover 10 (loosening the fixing screws, moving them axially, and then tightening them again), the adjustment range reaches 20 cm, covering the entire length of secondary coil 7, allowing for Q optimization over a wide range. Primary coil 8 passes through the central circular hole of the fixing frame 9 into the interior of secondary coil 7, and is coaxially arranged with secondary coil 7, not moving with the sliding frame 6. External radio frequency signals are input to primary coil 8 via the BNC radio frequency input terminal 15, inducing a high-voltage radio frequency potential in secondary coil 7 through mutual inductance.

[0062] Adjustment mechanism: includes a sliding frame 6, a fixed frame 9, and a threaded rod 4 (0.25 mm pitch) made of RENY (glass fiber reinforced polyamide MXD6), as well as a stepper motor 1.

[0063] The fixed frame 9 has a central circular hole for the primary coil 8 to pass through. The frame has coil grooves (up to 3 mm deep) that match the wire profile of the secondary coil 7. The secondary coil 7 is embedded in the coil grooves and secured by coil clamps and screws. The ends of the secondary coil 7 pass through the sliding frame 6 and the fixed frame 9 and are connected to the first output terminal 13 and the second output terminal 14, respectively. The sliding frame 6 has three functions integrated into a single RENY component:

[0064] ① External nut function: It engages with the threaded rod 4 to convert the rotational motion of the threaded rod 4 into its own axial translation, and the threaded rod 4 is axially fixed and does not move.

[0065] ② Coil carrier function: The coil is fixed by a coil slot whose surface matches the wire type of the secondary coil 7. A 0.5mm thick silicone rubber elastic buffer layer is provided at the bottom of the slot to absorb the axial tension of the coil, avoid plastic fatigue caused by repeated deformation of the annealed copper wire, and adjust the cycle life to >100,000 times.

[0066] ③ Guide and limit function: The outer circumference is provided with a guide groove, which slides with the guide rail 5 fixed inside the shielding cylinder 3 (gap <0.02 mm), restricting its own rotational freedom, ensuring that the sliding frame 6 can only move along the axial direction without radial wobble, and the axial movement of the coil is stable during the pitch adjustment process, and the linearity error of the inductance adjustment is <1%.

[0067] The threaded rod 4 is threadedly engaged with the sliding frame 6. When the stepper motor 1 drives the threaded rod 4 to rotate, the threaded rod 4 drives the sliding frame 6 to move axially, causing the secondary coil 7 to be compressed or stretched. A 608ZZ miniature deep groove ball bearing is installed in the central shaft hole of the shielding top cover 2. The upper end of the threaded rod 4 passes through the inner hole of the bearing and is axially limited by an E-type retaining ring, ensuring that the threaded rod 4 rotates only around its own axis during operation and its axial position is fixed. This prevents the threaded rod 4 from slightly shifting due to motor start-stop impact, eliminates adjustment backlash, and ensures a frequency repeatability error of <0.05 MHz. (Reference) Figure 6 The portion of the threaded rod 4 extending out of the shielding top cover 2 is fitted with a brass shielding cover 16 (wall thickness 0.5 mm) that is in communication with the shielding top cover 2. The brass shielding cover 16 extends along the threaded rod 4 toward the motor and has a PTFE sealing ring insulation gap reserved on the side near the flexible coupling 12 to prevent external electromagnetic interference from coupling to the coil.

[0068] Stepper motor mounting structure: The front end cover of stepper motor 1 has two mounting holes with a spacing of 35 mm, suitable for M3 screws. Stepper motor 1 is fixed to the outside of shielding top cover 2 via motor bracket 11: the lower plane of motor bracket 11 fits against the outer surface of shielding top cover 2 and is fixed with screws, with a PTFE insulating pad between them; the upper plane of motor bracket 11 fixes the front end face of stepper motor 1, and the two mounting holes on the front end face of the motor are respectively inserted into the threaded holes on the upper plane of the bracket and locked. The output shaft of stepper motor 1 points vertically downwards into the electromagnetic shielding housing and is coaxially aligned with the upper end of the flexible coupling 12. The vertical connecting section of the bracket provides sufficient axial clearance space for the motor after installation, ensuring coaxial transmission of the motor shaft, flexible coupling 12, and threaded rod 4. Conductive springs are provided between motor bracket 11 and shielding cylinder 3 to ensure continuous electromagnetic shielding. The lead wire of stepper motor 1 is threaded through a 3 mm ferrite magnetic ring before connecting to the driver to prevent motor PWM drive noise from coupling to the secondary coil 7.

[0069] The flexible coupling 12 and its connection to the transmission structure: The output shaft of the stepper motor 1 (φ5.0 mm, D-shaped bevel) and the upper smooth shaft section of the threaded rod 4 (machined to φ5.0 mm) are connected via the flexible coupling 12. The coupling has an outer diameter of 15.5 mm and a total length of approximately 27 mm. The middle section is a bellows-shaped elastic body section, and each end of the end section has an M3 set screw on its sidewall. The upper set screw is locked onto the D-shaped bevel plane of the motor output shaft to prevent slippage, while the lower set screw locks the upper smooth shaft of the threaded rod 4. During normal operation, both set screws are locked, and the motor drives the threaded rod 4 to rotate via the flexible coupling 12. In case of emergency manual adjustment, only the upper set screw is loosened to disengage the coupling from the motor shaft. The outer diameter of the flexible coupling 12 is then rotated by hand, causing the threaded rod 4 to rotate, thereby driving the sliding frame 6 to translate and adjust the pitch. After adjustment, the upper set screw is tightened again to restore electric control. This structure requires no disassembly of any parts, balancing automated control and experimental reliability.

[0070] Input / output interface: BNC interface.

[0071] 2. Dual-channel inverting (180° phase difference) output structure

[0072] This invention features a dual-channel output structure: the secondary coil 7 has a first output terminal 13 and a second output terminal 14 led out from its two ends. These two output terminals are physically the two ends of the secondary coil 7, and their radio frequency potentials relative to the electromagnetic shielding shell (common ground) are the same in frequency, equal in amplitude, and opposite in phase (180° difference), forming a balanced output structure that achieves inverted output without additional circuitry. Because the secondary coil 7 is a continuously wound helical structure, the two outputs are factory-set to maintain amplitude balance (amplitude difference <1%) and precise inversion (180°±0.5°), eliminating the need for additional calibration or balancing circuitry. The two output terminals are connected to adjacent electrodes of the ion trap, providing an inverted radio frequency potential to the ion trap. This dual-channel inverted driving method effectively suppresses common-mode noise, improves the trapping stability of the ion trap, and achieves a higher effective potential at the trap center under the same input power.

[0073] 3. Frequency Adjustment Principle

[0074] The resonant frequency of the spiral resonator is given by formula (1):

[0075] (1)

[0076] in, Angular frequency, The inductance of the secondary coil, This is the capacitance of the resonator itself (approximately 10 pF). This is the load capacitance (the equivalent capacitance of the ion trap system, including the AC / DC coupling circuit, is approximately 125 pF). This is achieved by changing the inductance of the secondary coil. The resonant frequency can be continuously adjusted.

[0077] The coil inductance is calculated using empirical formula (2):

[0078] (2)

[0079] Where b is the height of the secondary coil, d=50 mm is the coil diameter, τ is the coil pitch, and D=80 mm is the diameter of the shielding cylinder.

[0080] From formula (2), we can see that the inductance It is inversely proportional to the square of the coil pitch τ—when the coil pitch increases, the inductance decreases and the resonant frequency increases; when the coil pitch decreases, the inductance increases and the resonant frequency decreases.

[0081] 4. Adjustment mechanism and tuning range

[0082] The adjustment mechanism includes a RENY precision threaded rod with a thread pitch of 0.25 mm. It is driven by a 28BYJ-48 stepper motor (step angle 5.625°, reduction ratio 1:64, output shaft step angle after reduction is about 0.08789°), and with a 1 / 16 microstepping driver, the output shaft step angle can reach about 0.005493°. When the stepper motor rotates, the sliding frame moves axially, and the pitch τ of the secondary coil changes continuously in the range of 2 mm to 8 mm. The theoretical pitch adjustment step length is about 3.8 nm, and the actual effective adjustment accuracy is better than 0.0005 mm (affected by mechanical backlash and load), and the corresponding resonant frequency adjustment resolution is better than 0.002 MHz. According to formula (2), when τ changes from 8 mm to 2 mm, the inductance The variation range is 1.87–7.50 μH. When the load capacitance is 135 pF (including the resonator's own capacitance of 10 pF and the ion trap system capacitance of 125 pF), the resonant frequency coverage range is 5–10 MHz, completely covering Ca. + (3-6 MHz) and Be + The optimal trapping frequency range is (9-14 MHz).

[0083] Tuning accuracy calculation process (theoretical basis):

[0084] The basic parameters of the 28BYJ-48 stepper motor are: step angle 5.625°, reduction ratio 1:64, output shaft step angle (full step) = 5.625° / 64 = 0.087890625°. With a 1 / 16 microstepping driver, the output shaft step angle = 0.087890625° / 16 = 0.0054931640625°. The number of revolutions per step = 0.0054931640625° / 360° = 1.5258789 × 10⁻⁶. -5 The threaded rod has a pitch of 0.25 mm, and the theoretical pitch adjustment step is 1.5258789 × 10⁻⁶. -5 ×0.25 mm = 3.8×10 -6 mm (approximately 3.8 nm). Due to the influence of thread fit clearance (0.0001–0.001 mm), gear backlash, and mechanical deformation, the actual effective adjustment accuracy is taken as 0.0005 mm. The sensitivity of the resonant frequency to the pitch is approximately 1.50 MHz / mm (derived from dL / dτ≈-1.22 μH / mm and df / dL≈-1.23 MHz / μH), corresponding to a frequency resolution of approximately 0.00075 MHz, conservatively rated as better than 0.002 MHz.

[0085] 5. Theoretical Performance Expectations

[0086] Quality factor Q: Quality factor Q = ωL / R, where R is the equivalent series loss resistance of the resonator. Because this invention employs a fully insulated (RENY frame + painted coil) structure, no metal conductor is introduced into the coil during adjustment, avoiding the additional energy dissipation caused by the "short-circuit turn effect" and eddy current losses in metal screw tuning schemes. All components of the adjustment mechanism that contact the RF field (threaded rod 4, sliding frame 6, fixed frame 9, coil clamp) are made of RENY material, with no metal conductor entering the secondary coil 7. Structurally, this completely avoids the short-circuit turn effect and eddy current losses of traditional metal screw tuning schemes. The Q value is >200 within the 5-10 MHz full tuning range, far exceeding the Q value level of general variable inductors (typically <100). Furthermore, the primary coil is fixed to the shielded bottom cover. By adjusting the axial position of the shielded bottom cover to change the relative distance between the primary coil and the secondary coil 7, the mutual inductance coupling strength and the quality factor Q value can be further optimized.

[0087] Voltage gain: When used in conjunction with a 40 dB power amplifier, it can amplify the signal source potential by more than 1000 times, meeting the requirements of the ion trap for high-voltage radio frequency signals.

[0088] Tuning accuracy: The 28BYJ-48 stepper motor, combined with a 1 / 16 microstepping driver, achieves an effective adjustment accuracy of approximately 0.0005 mm, corresponding to a resonant frequency adjustment resolution better than 0.002 MHz, which is far higher than the accuracy requirements for frequency switching in ion trap experiments (typically ≤0.01 MHz).

[0089] Dual-channel output is balanced by default: the secondary coil 7 is a continuously wound spiral structure. The first and second output terminals are balanced by default (amplitude difference <1%) and precisely inverted (180°±0.5°) in the factory state, without the need for additional adjustment or balancing circuits.

[0090] Specific examples are provided below:

[0091] Implementation Method 1: Structural Assembly

[0092] The electromagnetic shielding shell consists of a shielding cylinder 3, a shielding top cover 2, and a shielding bottom cover 10. It is made of copper with a wall thickness of 2 mm, and the inner diameter D of the shielding cylinder 3 is 80 mm. The shielding top cover 2 and the shielding bottom cover 10 are fixedly connected to the shielding cylinder 3 with screws, and conductive springs are added at the joints to ensure the continuity of the electromagnetic shielding.

[0093] The secondary coil 7 is wound with annealed copper wire of 2 mm diameter, with N=10 turns and a coil diameter of d=50 mm. Except for 10 mm of bare copper at each end for soldering, the rest of the coil is coated with insulating varnish.

[0094] The sliding frame 6 and the fixed frame 9 are made of RENY material. The fixed frame 9 is fixed inside the shielding cylinder 3, and the sliding frame 6 mates with the threaded rod 4. Two symmetrical guide rails 5 (RENY material, rectangular cross-section) are fixed axially on the inner side of the shielding cylinder 3. The outer circumference of the sliding frame 6 has guide grooves corresponding to the positions of the guide rails 5. The grooves fit onto the guide rails 5, and the two slide together with a guide gap of <0.02 mm, ensuring that the sliding frame 6 can only move axially and cannot rotate. A circular hole (30 mm in diameter, see...) is opened in the center of the fixed frame 9. Figure 3 The primary coil 8 passes through a groove 3 mm deep, which is designed to accommodate the secondary coil 7. The groove's profile matches that of the secondary coil 7, and a 0.5 mm thick silicone rubber elastic buffer layer is placed at the bottom of the groove. The secondary coil 7 is embedded in the groove and secured with RENY material coil clamps and screws to prevent relative slippage or deformation during adjustment. The port of the secondary coil 7 passes through the frame and connects to BNC output terminals 13 and 14.

[0095] A 608ZZ miniature deep groove ball bearing is installed in the central shaft hole of the shielding top cover 2. The upper end of the threaded rod 4 passes through the inner hole of the bearing and is axially limited by an E-type retaining ring, so that the threaded rod 4 rotates only around its own axis and its axial position is fixed during operation. The part of the threaded rod 4 that extends out of the shielding top cover 2 is fitted with a brass shielding cover 16 (wall thickness 0.5 mm) that is in communication with the shielding top cover 2. The brass shielding cover 16 extends along the threaded rod 4 towards the motor and has a PTFE sealing ring insulation gap reserved near the flexible coupling 12.

[0096] The threaded rod 4 is machined with a precision thread (pitch 0.25 mm). A section of smooth shaft (machined to φ5.0 mm) extends from the upper end of the threaded rod 4 for connection to the coupling. After passing through the shielding top cover 2, the threaded section of the threaded rod 4 engages with the internal thread of the sliding frame 6. The output shaft of the stepper motor 1 (φ5.0 mm, D-shaped bevel) is connected to the smooth shaft section at the upper end of the threaded rod 4 via a flexible coupling 12. The coupling has an outer diameter of 15.5 mm and a total length of approximately 27 mm, with an M3 set screw at each end of the clamping section. The upper set screw locks the motor output shaft (the set screw presses against the D-shaped bevel plane to prevent slippage), and the lower set screw locks the smooth shaft at the upper end of the threaded rod 4. When the stepper motor 1 rotates, it drives the threaded rod 4 to rotate synchronously via the coupling 12, and the threaded rod 4 then drives the sliding frame 6 to translate axially through the threaded engagement. In case of emergency manual adjustment, simply loosen the upper set screw to disengage the coupling from the motor shaft, pinch the outer diameter (15.5 mm) of the coupling by hand and rotate it to drive the threaded rod 4 to rotate, thereby manually adjusting the pitch; after completion, tighten the upper set screw again to restore electric control.

[0097] Stepper motor 1 is fixed to the outside of shielding top cover 2 via RENY motor bracket 11. The front end cover of the motor has two mounting holes (35 mm apart, for M3 screws). The lower surface of the motor bracket 11 fits against the outer surface of the shielding top cover 2 and is fixed with screws, with a PTFE insulating pad between them. The upper surface of the bracket fixes the front end face of stepper motor 1, and M3 screws are inserted into the threaded holes on the upper surface of the bracket to lock them in place. The motor output shaft points vertically downwards into the electromagnetic shielding housing and is coaxially aligned with the upper end of the coupling 12. The vertical connecting section of the motor bracket 11 provides sufficient axial clearance for the motor after installation, ensuring coaxial transmission of the motor shaft, flexible coupling 12, and threaded rod 4. Conductive springs are provided between the bracket and the shielding cylinder 3 to ensure continuous electromagnetic shielding. The lead wires of stepper motor 1 are threaded through a 3 mm ferrite core before connecting to the driver to prevent PWM drive noise from coupling to the secondary coil 7.

[0098] The primary coil 8 is wound with annealed copper wire of 1 mm diameter, with 2 turns, and a coil diameter of approximately 20 mm. It is fixed inside the shielding base 10 and moves axially with the shielding base 10. The BNC RF input terminal 15 is installed on the outside of the shielding base 10. The primary coil 8 passes through the central circular hole of the fixing frame 9 and enters the secondary coil 7, arranged coaxially with the secondary coil 7, and does not move with the sliding frame 6. By adjusting the axial position of the shielding base 10 (loosening the fixing screw, moving it axially, and then tightening it again), the adjustment range is up to 20 cm, which can change the axial distance between the primary coil 8 and the secondary coil 7, thereby adjusting the mutual inductance coupling strength over a large range and optimizing the quality factor Q value.

[0099] BNC output terminals 13 and 14 are mounted on shielding cylinder 3.

[0100] Implementation Method 2: System Connection and Operating Status

[0101] The complete connection method of the resonator of the present invention in the ion trap radio frequency system is as follows:

[0102] The arbitrary waveform generator is connected to the power amplifier via a BNC to SMA cable. The power amplifier is connected to the BNC RF input terminal 15 of the resonator via an SMA to BNC cable. The first output terminal 13 and the second output terminal 14 of the resonator are connected to the AC / DC coupling circuit via BNC cables. The static DC power supply is connected to the AC / DC coupling circuit via wires. The AC / DC coupling circuit is connected to the ion trap via vacuum enameled wires.

[0103] During operation, a sinusoidal radio frequency potential (e.g., 6 MHz frequency, peak-to-peak value 0.5-1 V) is generated by an arbitrary waveform generator. After amplification by a power amplifier (40 dB gain), the peak-to-peak value reaches 50-100 V. This potential is then connected to the primary coil 8 via the BNC radio frequency input terminal 15. Through mutual inductance, a high-voltage radio frequency potential is induced in the secondary coil 7. After amplification by a resonator, the peak-to-peak value can reach 500-1000 V, while maintaining a constant frequency. A static DC power supply generates an electrostatic potential (typically less than 5 V), which is coupled to the radio frequency potential through an AC / DC coupling circuit, ultimately providing the trapping potential for the ion trap.

[0104] Implementation Method 3: Frequency Adjustment Operation

[0105] When it is necessary to imprison Ca + During ionization (target frequency 5-6 MHz), the host computer controls stepper motor 1 to rotate in the forward direction, causing the sliding frame to move towards the fixed frame, compressing the secondary coil to a smaller pitch state (about 2-3 mm). At this time, the inductance increases and the resonant frequency decreases to the target range.

[0106] When you need to switch to Be + During ionization (target frequency 9-10 MHz), the host computer controls stepper motor 1 to rotate in the opposite direction, causing the sliding frame to move away from the fixed frame and stretch the secondary coil to a larger pitch (about 7-8 mm). At this time, the inductance decreases and the resonant frequency increases to the target range.

[0107] With a threaded rod pitch of 0.25 mm, coupled with a 28BYJ-48 stepper motor (step angle 5.625°, reduction ratio 1:64) and a 1 / 16 microstepping driver, the actual effective adjustment accuracy is approximately 0.0005 mm, and the frequency adjustment resolution is better than 0.002 MHz. The switching time is no more than 2 seconds.

[0108] Implementation Method 4: Theoretical Parameter Table (Expected Values)

[0109]

[0110] Note: The above data are based on theoretical calculations using formulas (1) and (2) and are derived from the low-loss characteristics of the RENY skeleton. The specific values ​​are subject to actual testing.

[0111] Implementation Method 5: Frequency Self-Calibration Method Based on Ion Fluorescence Feedback

[0112] S1: The host computer (i.e., the experimental control computer) is connected to the arbitrary waveform generator, the driver of stepper motor 1, and the photodetector via the USB interface; the host computer controls the arbitrary waveform generator to output the initial frequency (e.g., 6 MHz, 0.5 Vpp) and controls the stepper motor 1 to reset to the midpoint of the pitch τ=5 mm.

[0113] S2: Traverse τ = 2 to 8 mm with a step size of Δτ = 0.5 mm. At each step, collect the ion fluorescence intensity in the ion trap through a photodetector to establish a "pitch τ-fluorescence intensity" mapping curve and lock the target pitch τ* and resonant frequency f0 corresponding to the fluorescence peak.

[0114] S3: Using a step size of Δτ = 0.025 mm (1 / 10 revolution), perform a fine scan within the range of τ* ± 0.5 mm to verify and refine the mapping curve, and establish a "Cytic species—τ*—f0" mapping table (Ca... + : τ≈7~8 mm, f0≈5~6 MHz; Be + :τ≈2~3 mm, f0≈9~10 MHz);

[0115] S4: When switching ion species, the host computer calls the target τ* in the mapping table and controls the stepper motor 1 to position to the target pitch within 2 seconds.

[0116] Implementation Method Six: Dynamic Tracking of Resonant Frequency and Temperature Drift Pre-compensation Method

[0117] During the experiment, the host computer monitors the output voltage amplitude of the secondary coil 7 in real time. When the amplitude drops by more than 5% (due to inductor drift caused by temperature changes), the computer automatically fine-tunes the rotation angle of the stepper motor 1 (0.01 revolutions) until the output voltage returns to the set value.

[0118] Preliminary tests showed that the coefficient of linear expansion of RENY material in the temperature range of 20–50°C was 3 × 10⁻⁶. -5 / °C, the host computer collects the resonator's operating temperature in real time (PT100 thermistor is attached to the surface of the fixed frame 9), and automatically calculates the thread rod compensation angle based on the temperature change ΔT to compensate for the pitch change caused by the thermal expansion of RENY, so that the frequency long-term stability reaches ±0.02 MHz for 24 hours.

[0119] Implementation Method 7: Rapid Switching Method for Multi-Ion Sequential Trapping

[0120] Preset Ca + Mg + Be + The target pitch value for multiple ions can be set, and the ion species can be switched with one click during the experiment. The stepper motor 1 completes the pitch adjustment within 2 seconds, supporting the alternating trapping experiment of multiple ions in the same ion trap.

[0121] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A dual-channel inverting output adjustable radio frequency spiral resonator, characterized in that, It includes an electromagnetic shielding housing, a primary coil (8), a pitch-adjustable secondary coil (7), and an adjustment mechanism; The primary coil (8) is arranged along the axial direction of the electromagnetic shielding shell on one side inside the electromagnetic shielding shell, and the two ends of the primary coil (8) are led out of the electromagnetic shielding shell as the input terminals (15) of the resonator to connect to external radio frequency signals. The secondary coil (7) is arranged inside the electromagnetic shielding shell along the axial direction of the electromagnetic shielding shell; the two ends of the secondary coil (7) are led out of the electromagnetic shielding shell and serve as the first output end (13) and the second output end (14) of the resonator, respectively. Through electromagnetic coupling with the primary coil (8), the first output end (13) and the second output end (14) output radio frequency signals with the same frequency, equal amplitude and 180° phase difference. The adjustment mechanism is used to change the pitch of the secondary coil (7) to achieve continuous change of the inductance of the secondary coil (7) and continuous adjustment of the resonant frequency of the resonator.

2. The dual-channel inverting output adjustable RF spiral resonator according to claim 1, characterized in that, The electromagnetic shielding shell includes a shielding cylinder (3), and a shielding top cover (2) and a shielding bottom cover (10) disposed at the upper and lower ends of the shielding cylinder (3) to enclose and form an internal shielding cavity. The shielding bottom cover (10) is slidably sleeved on the end of the shielding cylinder (3). The primary coil (8) is fixed on the inner side of the shielding bottom cover (10) and moves along the axial direction of the electromagnetic shielding shell with the shielding bottom cover (10) to adjust the axial distance between it and the secondary coil (7), thereby changing the mutual inductance coupling strength and optimizing the quality factor Q value.

3. A dual-channel inverting output adjustable radio frequency spiral resonator according to claim 2, characterized in that, The adjustment mechanism includes a fixed frame (9), a sliding frame (6), a threaded rod (4), and a stepper motor (1). The threaded rod (4) is arranged inside the electromagnetic shielding shell along the axial direction of the electromagnetic shielding shell, and one end of the threaded rod (4) extends out of the shielding top cover (2) and is connected to the stepper motor (1) for transmission. The fixed frame (9) and the sliding frame (6) are located inside the shielding cylinder (3) and are arranged along the axial direction of the electromagnetic shielding shell; the fixed frame (9) is fixedly connected to the shielding cylinder (3) and is used to fix one end of the secondary coil (7); The sliding frame (6) is located on the side of the fixed frame (9) near the shielding top cover (2) and is used to fix the other end of the secondary coil (7); the sliding frame (6) is sleeved on the threaded rod (4) and threadedly engaged with the threaded rod (4), and the sliding frame (6) is slidably engaged with the guide rail (5) fixed to the inner wall of the shielding cylinder (3) through the guide groove on the outer periphery; The stepper motor (1) drives the threaded rod (4) to rotate, and through the threaded engagement, drives the sliding frame (6) to move along the axial direction of the electromagnetic shielding shell, so as to change the pitch of the secondary coil (7).

4. A dual-channel inverting output adjustable radio frequency spiral resonator according to claim 3, characterized in that, The fixed frame (9) has a through hole in the middle for the primary coil (8) to pass through, so that the primary coil (8) is located inside the secondary coil (7); the primary coil (8) and the secondary coil (7) are arranged coaxially, and the diameter of the primary coil (8) is smaller than the diameter of the secondary coil (7).

5. A dual-channel inverting output adjustable RF spiral resonator according to claim 3, characterized in that, The fixed frame (9) and the sliding frame (6) are respectively provided with coil slots that match the shape of the secondary coil (7). The two ends of the secondary coil (7) are respectively embedded in the coil slots of the fixed frame (9) and the sliding frame (6) and fixed by coil clamping plates.

6. The dual-channel inverting output adjustable RF spiral resonator according to claim 3, characterized in that, The shielding top cover (2) has a bearing in the central shaft hole. The upper end of the threaded rod (4) passes through the inner hole of the bearing and is axially limited by the E-type retaining ring, so that the threaded rod (4) can only rotate around its own axis and its axial position is fixed. The portion of the threaded rod (4) extending out of the shielding top cover (2) is fitted with a brass shielding cover (16) that is in communication with the shielding top cover (2). The brass shielding cover (16) extends along the threaded rod (4) toward the motor and has a reserved sealing ring insulation gap on the side near the flexible coupling (12). The output shaft of the stepper motor (1) and the threaded rod (4) are connected by a flexible coupling (12). The flexible coupling (12) adopts a double top screw clamping structure to realize the switching of manual drive mode: loosen the top screw on the motor side to disengage the flexible coupling (12) from the motor output shaft, and drive the threaded rod (4) to rotate by manually rotating the flexible coupling (12).

7. The dual-channel inverting output adjustable RF spiral resonator according to claim 5, characterized in that, The stepper motor (1) is fixed to the outside of the shielding top cover (2) by a motor bracket (11); an insulating pad is provided between the motor bracket (11) and the shielding top cover (2), and a conductive spring is provided between the motor bracket (11) and the electromagnetic shielding shell to ensure the continuity of electromagnetic shielding; the lead wire of the stepper motor (1) passes through the ferrite magnetic ring and is connected to the driver to avoid driving noise coupling to the secondary coil (7).

8. A dual-channel inverting output adjustable RF spiral resonator according to claim 7, characterized in that, The fixed frame (9), sliding frame (6), threaded rod (4), guide rail (5), coil clamp and motor bracket (11) are all made of glass fiber reinforced polyamide MXD6 (RENY); the surface of the secondary coil (7) is coated with an insulating paint layer except for the electrical connection sections reserved at both ends, to ensure inter-turn insulation.

9. A method of using a dual-channel inverting output adjustable radio frequency spiral resonator based on any one of claims 1-8, characterized in that, Resonator frequency self-calibration methods include: Connect the first output terminal (13) and the second output terminal (14) of the resonator to the adjacent electrodes of the ion trap; The host computer is connected to the arbitrary waveform generator, the driver of the stepper motor (1) and the photodetector respectively. The photodetector is used to collect the fluorescence signal of ions in the ion trap. The host computer controls the stepper motor (1) to drive the threaded rod (4) to rotate, thereby changing the pitch τ of the secondary coil (7), and controls the arbitrary waveform generator to output a sine signal with a scanning frequency to the input terminal (15) of the resonator. The intensity of ion fluorescence in the ion trap is collected by a photodetector, a mapping curve between the pitch τ and the fluorescence intensity is established, and the target pitch τ* and resonant frequency f0 corresponding to the fluorescence peak are locked. Establish a mapping table between ion species, target pitch τ*, and resonant frequency f0; when switching ion species, call the corresponding target pitch τ* value in the mapping table and control the stepper motor (1) to position to the target pitch; When establishing the mapping curve between pitch τ and fluorescence intensity, a coarse scan is first performed within the pitch adjustment range of the secondary coil (7) with a first step length, and then a fine scan is performed near the target pitch obtained by the coarse scan with a second step length smaller than the first step length to achieve the calibration of the target pitch.

10. The method of using the dual-channel inverting output adjustable RF spiral resonator according to claim 9, characterized in that, It also includes a frequency dynamic tracking step: The output voltage amplitude of the secondary coil (7) is monitored in real time. When the voltage amplitude drops below the preset threshold, the rotation angle of the stepper motor (1) is finely adjusted by the host computer until the output voltage amplitude recovers. The linear expansion coefficient of the thread rod material is obtained in advance, and the operating temperature of the resonator is collected in real time by the host computer. The rotation angle of the thread rod is automatically adjusted according to the temperature change to compensate for the pitch change caused by thermal expansion.

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