Ion trap buffer gas parameter design method
By optimizing the buffer gas parameters of the ion trap using Simion electromagnetic simulation software and LUA programming, the problem of poor buffer gas parameter matching was solved, and rapid ion cooling and efficient buffer gas parameter design were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LANZHOU INST OF PHYSICS CHINESE ACADEMY OF SPACE TECH
- Filing Date
- 2022-11-07
- Publication Date
- 2026-07-24
AI Technical Summary
In existing technologies, poor matching of buffer gas parameters leads to low ion cooling efficiency.
The Simion electromagnetic simulation software was used to create the ion trap electrode array and electromagnetic field. Combined with LUA programming, the parameters of the buffer gas in different types of ion traps were simulated. The design method was used to optimize the parameters of the buffer gas, and the design method of the ion trap was implemented. The design method of ion movement was simulated using simulation software, and the design method of buffer ion trap was optimized. The design parameters of the ion trap were optimized.
Rapid ion cooling was achieved, improving the reliability of the buffer gas cooling effect and the efficiency of parameter optimization.
Smart Images
Figure CN115526065B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of time and frequency technology, and more specifically, to a method for designing parameters of an ion trap buffer gas. Background Technology
[0002] Ions trapped in ultra-high vacuum ion traps are free from collisions with the trap walls and external interference. The interaction time between ions and the microwave field is unrestricted, which is beneficial for improving short-term stability. Ion trap frequency standards are widely regarded as a promising next-generation high-precision, high-stability time and frequency standard. Ion trapping technology in ion traps and improving the ion trapping effect are important aspects of ion trap frequency standard research.
[0003] In ion trap frequency standards, to narrow the linewidth, the interaction time between ions and the microwave field must be increased. Therefore, it is necessary to cool the ions and extend the trapping time. Using a buffer gas is the most effective and practical way to cool ions in the ion trap to room temperature. Lightweight, chemically stable inert gases are typically chosen for buffer gas cooling. During collisions, buffer gas atoms (molecules) and trapped ions exchange kinetic energy, continuously reducing the kinetic energy of the trapped ions and cooling their velocity. Theoretically, this can cool the ions to the temperature of the buffer gas.
[0004] Because the pressure of the buffer gas is relatively low, the gas in the ion trap can be considered as an ideal gas, thus obtaining the cooling motion equation of the ions in the ion trap. The above calculation process is simulated using Simion electromagnetic simulation software and LUA programming. The cooling effect of the buffer gas on the ions in the ion trap is analyzed and compared, and the optimal parameters of the buffer gas are designed. Summary of the Invention
[0005] This application provides a method for designing buffer gas parameters in an ion trap, which solves the problems of poor matching degree and low efficiency of buffer gas parameters in actual design. The optimal design parameters of the buffer gas in the ion trap can be determined through this design method, so as to achieve rapid ion cooling.
[0006] To achieve the above objectives, this application provides a method for designing buffer gas parameters for an ion trap, comprising the following steps: Step 1: Creating an ion trap electrode array using simulation software; Step 2: Creating a spatial grid potential field for the ion trap using simulation software, and then setting initial parameters for the ions and buffer gas in the ion trap to prepare initial conditions for the ion motion equation; Step 3: Deriving the motion equation of ions in the ion trap under the action of the viscous force of the buffer gas; Step 4: Writing a software program based on the motion equation to realize the simulated control of ions under the action of the buffer gas; Step 5: Simulating the motion of ions under different types of buffer gases, and designing the type of buffer gas based on the motion amplitude of the ions; Step 6: Determining the type of buffer gas, simulating the motion of ions under different pressures of the buffer gas, and designing the pressure of the buffer gas based on the motion amplitude of the ions; Step 7: Simulating the decay process of ions at different temperatures of the buffer gas, and designing the temperature of the buffer gas based on the decay rate of the ion number; Step 8: Completing the design of the buffer gas parameters based on the obtained buffer gas type, buffer gas pressure, and buffer gas temperature.
[0007] Furthermore, the simulation software used in step 1 is Simion electromagnetic simulation software.
[0008] Furthermore, in step 1, an ion trap electrode array is created using Simion electromagnetic simulation software through an electrode file written in a window or electrode definition language.
[0009] Furthermore, in step 2, the electrode array is incorporated into the Poisson equation using Simion electromagnetic simulation software, and the spatial grid potential field of the ion trap is created after calculation.
[0010] Furthermore, in step 4, a software program is written based on the equation of motion to form a .LUA file, which simulates and controls the parameters and motion process of ions to obtain an intuitive diagram of ion motion trajectory and ion number decay effect.
[0011] The present invention provides a method for designing parameters of an ion trap buffer gas, which has the following advantages:
[0012] This application uses electromagnetic simulation software to simulate the motion state of ions and optimize key buffer gas parameters, which can improve the reliability of the evaluation of the buffer gas cooling effect on ions. It has the characteristics of intuitive ion motion state and high efficiency in buffer gas parameter optimization, and can be used for the analysis of the interaction state of ions and gas molecules and parameter optimization. Attached Figure Description
[0013] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:
[0014] Figure 1 This is a flowchart of the ion trap buffer gas parameter design method provided in the embodiments of this application;
[0015] Figure 2 These are simulation diagrams of the trajectories of ions after cooling under the action of different types of gases according to the embodiments of this application (the left diagram is of helium, and the right diagram is of argon).
[0016] Figure 3 This is a simulation diagram of the trajectories of ions after cooling under the action of argon gas at different pressures, according to the embodiments of this application (dark line is 3E-2Pa, light line is 2E-2Pa);
[0017] Figure 4 This is a simulation diagram of the ion number decay after ion cooling under the action of argon gas at different temperatures, according to the embodiments of this application (temperatures from left to right are 380, 330K, 270K, and 100K). Detailed Implementation
[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0020] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.
[0021] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0022] In addition, the term "multiple" should mean two or more.
[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0024] like Figure 1 As shown, this application provides a method for designing parameters of an ion trap buffer gas, including the following steps:
[0025] Step 1: Create an ion trap electrode array using simulation software in order to determine the ion trap electric field;
[0026] Step 2: Use simulation software to create the spatial grid potential field of the ion trap, and then set the initial parameters of the ions and buffer gas in the ion trap (including the number of ions, ion mass, ion charge, initial position and velocity distribution of ions, etc.), the type and pressure of the buffer gas, to prepare the initial conditions for the ion motion equation.
[0027] Step 3: Derive the equation of motion of ions in the ion trap under the action of the viscous force of the buffer gas;
[0028] Step 4: Write a software program based on the equation of motion to simulate and control the ions under the action of the buffer gas;
[0029] Step 5: Simulate the movement of ions under different types of buffer gases, and design the type of buffer gas based on the amplitude of ion movement;
[0030] Step 6: Determine the type of buffer gas, simulate the movement of ions under different pressures of the buffer gas, and design the pressure of the buffer gas based on the amplitude of ion movement.
[0031] Step 7: Simulate the decay process of ions at different temperatures in the buffer gas, and design the temperature of the buffer gas based on the decay rate of the number of ions;
[0032] Step 8: Based on the obtained buffer gas type, buffer gas pressure, and buffer gas temperature, complete the design of the buffer gas parameters.
[0033] Furthermore, the simulation software in step 1 is Simion electromagnetic simulation software. First, the ion trap electrode array is created using the Simion electromagnetic simulation software through the window or the electrode file written in the electrode definition language. Then, the electrode array is substituted into the Poisson equation using the Simion electromagnetic simulation software to calculate and create the spatial grid potential field of the ion trap.
[0034] Furthermore, in step 4, a software program is written based on the equation of motion to form a .LUA file, which simulates and controls the parameters and motion process of ions to obtain an intuitive ion trajectory and ion number decay effect diagram. Then, different parameters of the buffer gas are designed, and the optimal design parameters are selected based on the ion trajectory and ion number decay effect diagram.
[0035] Specifically, the ion trap buffer gas parameter design method provided in this application uses electromagnetic simulation software to simulate the motion state of ions in the ion trap. Based on the observed ion trajectory and ion decay process, the parameters of the buffer gas can be optimized, enabling efficient design of the buffer gas parameters and achieving rapid ion cooling. The following uses a quadrupole ion trap as an example to further illustrate this application:
[0036] First, an ion trap electrode array is created using Simion electromagnetic simulation software through an electrode file written in the window or electrode definition language. Then, the electrode array is substituted into the Poisson equation through the software, and the spatial grid potential field of the ion trap is created after calculation. Finally, the initial parameters of the ions and buffer gas are set.
[0037] When ions and buffer gas molecules reach thermal equilibrium within the ion trap, the energy loss from collisions between ions and buffer gas molecules equals the energy gained by the ions from the electric field. The average change in ion momentum in the direction of the electric field per unit time is proportional to the magnitude of the electric field force. The ions experience a viscous force F from the buffer gas molecules. m It can be represented as:
[0038]
[0039] Among them, F q q represents the magnitude of the electric force acting on the ion. e V is the ionic charge, E is the equivalent electric field, and v is the effective electric field. m denoted as ion velocity, and ion mobility k. m Defined as:
[0040]
[0041] Where m is the mass of the ion, M is the mass of the buffer gas molecule, N is the number density of the buffer gas molecule, and k B Let D(T) be the Boltzmann constant. eff () represents the interaction temperature T between ions and molecules. eff The collision cross-sectional area below.
[0042] The equation of motion of ions in the quadrupole ion trap, bound by the potential field of the ion trap and the viscous force of the buffer gas, is as follows:
[0043]
[0044]
[0045] Where U0 is the DC bias of the alternating electric field applied to the ion trap, V0 is the amplitude of the alternating electric field, Ω is the angular frequency of the alternating electric field, and r0 is the shortest distance from the center of the ion trap to the surface of the trap electrode.
[0046] Based on the above motion equations, a program file is written according to the LUA syntax requirements. The viscous force on the ions is added to the ion motion equations, and the value range and step size of specific electrical parameters are set. The parameters and motion process of the ion motion process are simulated and controlled to realize the ion simulation process under the action of buffer gas. After simulation, an intuitive ion motion trajectory and ion number decay effect diagram are obtained.
[0047] First, change the type of gas, such as Figure 2 As shown, taking helium and argon as examples, the trajectory of ions was simulated and the trajectory diagrams of ions under the two gases were obtained. After comparison, it was found that argon has a greater attenuation of the amplitude of ion movement and a stronger cooling effect than helium.
[0048] Argon was chosen as the buffer gas, and then the argon gas pressure was designed, such as... Figure 3 As shown, argon gas pressures of 3E-2Pa and 2E-2Pa were set, and ion trajectories were simulated to obtain ion trajectory diagrams under the two pressures. After comparison, it was found that the ion movement amplitude was smaller and the cooling effect was better under the higher buffer gas pressure.
[0049] Finally, the temperature of the argon gas was designed, such as... Figure 4 As shown, argon gas temperatures of 380K, 330K, 270K, and 100K were set to simulate the decay of ion numbers over time after ion trapping. The comparison revealed that the ion number decayed more slowly and the trapping effect was better at lower buffer gas temperatures. However, the cost of maintaining lower buffer gas temperatures would increase significantly. Therefore, the temperature of the buffer gas should be maintained at a temperature that is easily achievable in the laboratory.
[0050] In the embodiments of this application, the parameters of the buffer gas mainly include the gas type, gas pressure, and gas temperature. Appropriate values are selected to complete the optimized design of the buffer gas parameters.
[0051] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for designing parameters of an ion trap buffer gas, characterized in that, Includes the following steps: Step 1: Create an ion trap electrode array using simulation software; The simulation software is Simion electromagnetic simulation software. The ion trap electrode array is created using Simion electromagnetic simulation software through window or electrode files written in the electrode definition language. Step 2: Use simulation software to create the spatial grid potential field of the ion trap, and then set the initial parameters of the ions and buffer gas in the ion trap to prepare the initial conditions for the ion motion equation. The electrode array was substituted into the Poisson equation using Simion electromagnetic simulation software, and the spatial grid potential field of the ion trap was created after calculation. Step 3: Derive the equation of motion of ions in the ion trap under the action of the viscous force of the buffer gas; Step 4: Write a software program based on the equation of motion to simulate and control the ions under the action of the buffer gas; Based on the equation of motion, a software program is written to form a .LUA file. The viscous force on the ions is added to the equation of motion, and the value range and step size of specific electrical parameters are set. The parameters and motion process of the ions are simulated and controlled to obtain an intuitive ion motion trajectory and ion number decay effect diagram. Step 5: Simulate the movement of ions under different types of buffer gases, and design the type of buffer gas based on the amplitude of ion movement; Step 6: Determine the type of buffer gas, simulate the movement of ions under different pressures of the buffer gas, and design the pressure of the buffer gas based on the amplitude of ion movement. Step 7: Simulate the decay process of ions at different temperatures in the buffer gas, and design the temperature of the buffer gas based on the decay rate of the number of ions; Lower buffer gas temperatures result in slower ion decay and better trapping, but maintaining these lower temperatures significantly increases costs. Therefore, the buffer gas temperature should be maintained at a level easily achievable in the laboratory. Step 8: Based on the obtained buffer gas type, buffer gas pressure, and buffer gas temperature, complete the design of the buffer gas parameters.