Method for measuring work function of thermionic energy converter receiving electrode

Abstract

Embodiments of the present application disclose a method for measuring a work function of a receiving electrode of a thermionic energy converter, so as to conveniently and efficiently determine the work function of the receiving electrode. The thermionic energy converter comprises an emitting electrode, a receiving electrode and a plasma, the plasma is arranged between the emitting electrode and the receiving electrode, and electrons emitted by the emitting electrode reach the receiving electrode via the plasma. The method comprises the following steps: S10, obtaining a volt-ampere characteristic curve of the receiving electrode electrode material at different receiving electrode temperatures T C ; S20, determining effective voltages U corresponding to target currents at different receiving electrode temperatures T C according to the volt-ampere characteristic curve; S30, calculating the work function of the receiving electrode at different receiving electrode temperatures T C under the target currents according to the effective voltages U corresponding to the different receiving electrode temperatures T C ​

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of thermionic power generation technology, specifically to a method for measuring the receiving pole work function of a thermionic energy converter. Background Technology

[0002] A thermionic energy converter (TEC) is a device that directly converts thermal energy into electrical energy based on the principle of thermionic emission. By combining with different heating methods, thermionic energy converters can be applied in various situations. Under arc conditions, the emitter of the thermionic energy converter (TEC) absorbs heat and emits electrons. The emitted electrons pass through the electrode gap filled with Cs plasma and reach the receiver. When a load is connected between the emitter and receiver, a circuit is formed to perform work, thus generating electricity.

[0003] As one of the core components of a thermionic energy converter, the electrode material of the receiving electrode has a decisive influence on power generation efficiency and operating life. The work function of the electrode material is an important parameter for evaluating the material. In TEC, due to the adsorption of Cs on the electrode surface, studying the work function of the electrode material after Cs adsorption (i.e., the effective work function) is more important than its vacuum work function. Summary of the Invention

[0004] According to one aspect of the present invention, a method for measuring the work function of the receiving electrode of a thermionic energy converter is provided to conveniently and efficiently determine the work function of the receiving electrode. The thermionic energy converter includes an emitter, a receiver, and a plasma, wherein the plasma is disposed between the emitter and the receiver, and electrons emitted from the emitter reach the receiver via the plasma. The measurement method includes: step S10, obtaining the work function of the receiving electrode material at different receiving electrode temperatures T. C Step S20: Based on the current-voltage characteristic curve, determine the current-voltage characteristic curve at different receiving electrode temperatures T. C The effective voltage U corresponding to the target current; Step S30, according to different receiving electrode temperatures T C Calculate the effective voltage U corresponding to the target current and the receiver electrode at different receiver electrode temperatures T. C Work function under

[0005] The measurement method in this embodiment of the invention only requires obtaining a series of current-voltage characteristic curves with only the temperature of the receiving electrode changed. Combined with the theoretical basis of the thermionic energy converter, the work function of the receiving electrode of the thermionic energy converter can be obtained through mathematical calculation. The method is simple and convenient to use. Attached Figure Description

[0006] Other objects and advantages of the invention will become apparent from the following description of embodiments of the invention with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the invention.

[0007] Figure 1 This is a schematic diagram illustrating the working principle of a thermionic energy converter according to an embodiment of the present invention.

[0008] Figure 2 This is a schematic flowchart of a receiving polarity function measurement method according to an embodiment of the present invention.

[0009] Figure 3 This is a graph showing the current-voltage characteristic at different receiving electrode temperatures according to an embodiment of the present invention.

[0010] Figure 4 This is a schematic diagram of a thermionic energy converter according to an embodiment of the present invention.

[0011] Figure 5 This is a flowchart illustrating the calculation of the work function in step S30 according to an embodiment of the present invention.

[0012] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only one embodiment of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0014] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by a person with ordinary skill in the art to which this application pertains. Where the terms "first," "second," etc., are used throughout the text, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data described by "first," "second," etc., can be interchanged where appropriate. Where "and / or" appears throughout the text, it means including three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. Furthermore, for ease of description, spatial relative terms such as "above," "below," "top," "bottom," etc., may be used here, only to describe the spatial positional relationship between one device or feature as shown in the figure and other devices or features. It should be understood that this also includes different orientations in use or operation besides those shown in the figure.

[0015] Thermionic energy converters can be combined with various heating devices; for example, they can be combined with nuclear reactor fission energy to create a thermionic reactor power source. Figure 1 As shown, the thermionic energy converter includes an emitter 10, a receiver 20, and a cesium source 30. The cesium source 30 fills the gap between the emitter 10 and the receiver 20 with cesium vapor 31. The cesium vapor 31 is ionized by electron collisions between the electrodes to form plasma, eliminating the potential barrier for electron transport. The nuclear reactor 100 can supply heat to the emitter 10. When the emitter 10 is heated to a high potential, it emits electrons 40. The electrons 40 pass through the cesium plasma and reach the surface of the receiver 20. The emitter 10 and the receiver 20 serve as the two poles of a power source. When a load 50 is connected between the emitter 10 and the receiver 20, a closed loop is formed to perform work.

[0016] Conventional work function measurement methods are mainly divided into two categories: absolute measurement methods and relative measurement methods. Absolute measurement methods include ultraviolet photoelectron spectroscopy (UPS), electron beam blocking potential method, and field emission blocking potential method; relative measurement methods include Kelvin probe force microscopy (KPFM) and thermionic emission blocking potential method. Currently, the most widely used and mature measurement methods are the UPS and Kelvin probe methods.

[0017] The inventors of this invention discovered that the work function of electrode materials is particularly sensitive to changes in material structure and composition, as well as surface physical and chemical properties. Therefore, work function testing of the receiving electrode should closely approximate its actual operating environment. However, under arc conditions, the receiving electrode in a thermionic energy converter operates in an environment of approximately 800K-1100K and 100-400Pa cesium vapor, and Cs atoms are adsorbed on its surface. Therefore, it is difficult to accurately measure the work function of the receiving electrode under these actual operating conditions using the conventional work function measurement methods described above.

[0018] In particular, the temperature of the receiving electrode in the thermionic energy converter is usually above 800K. However, the cost of in-situ heating of the electrode material in UPS and Kelvin probe testing devices is very high, and the UPS probe is difficult to operate normally at ultra-high temperatures. As a result, the work function results of UPS and Kelvin probe testing cannot match the actual operating temperature of the electrode material.

[0019] Furthermore, UPS testing requires the sample to be in a high vacuum environment. Pre-adsorbing Cs atoms onto the electrode material sample before measurement partially solves the Cs adsorption problem. However, the desorption of Cs atoms during sample transfer, the uncertainty of the adsorbed amount of Cs atoms, and the surface state make this method unsuitable for measuring the work function of the receiving electrode in a thermionic converter. Additionally, the Au probe is severely corroded by Cs vapor during Kelvin probe testing, affecting the calibration values. Therefore, the Kelvin probe method cannot be used to accurately measure the work function of the receiving electrode with Cs adsorption.

[0020] In summary, there is currently no suitable method for measuring the work function of a thermionic converter receiver under service conditions close to those of a real-world service environment. Therefore, embodiments of the present invention provide a method for measuring the work function of a thermionic converter receiver under conditions close to actual service conditions.

[0021] like Figure 2 As shown, the method for measuring the receiving polarity work function of the thermionic energy converter in this embodiment of the invention includes the following steps S10 to S30.

[0022] Step S10: Obtain the receiving electrode material at different receiving electrode temperatures T C The current-voltage characteristic curve is shown below.

[0023] Step S20: Based on the current-voltage characteristic curve, determine the temperature T at different receiving electrode temperatures. C The effective voltage U corresponding to the target current. Here, the effective voltage is the output voltage of the thermionic energy converter.

[0024] Step S30, according to different receiving electrode temperatures T C Calculate the effective voltage U corresponding to the target current and the receiver electrode at different receiver electrode temperatures T. C Work function under

[0025] The measurement method in this embodiment of the invention only requires obtaining the current-voltage characteristic curves of the receiving electrode material at different receiving electrode temperatures under near-real service conditions. Combined with the theoretical basis of the thermionic energy converter, the work function of the receiving electrode of the thermionic energy converter can be calculated online in real time based on the obtained current-voltage characteristic data. The method is simple and convenient to use.

[0026] In some embodiments, step S10 includes: conducting a current-voltage characteristic power generation experiment on the thermionic energy converter at different receiving electrode temperatures T. C Tests were conducted to obtain the receiving electrode material at different receiving electrode temperatures T. CThe current-voltage characteristic power generation data is shown below; based on the current-voltage characteristic power generation data, plot the receiving electrode material at different receiving electrode temperatures T. C The current-voltage characteristic curve is shown below.

[0027] In this embodiment, a conventional flat-plate thermionic energy conversion experimental platform can be used to test the receiver and emitter to obtain volt-ampere characteristic power generation data, eliminating the need to build a complex testing platform. Furthermore, testing can be conducted under the service conditions of the receiver, allowing for in-depth analysis of experimental data on the power generation of the receiver electrode material. This data can be combined with theoretical calculations to conveniently, efficiently, and more accurately determine the work function of the receiver under high-temperature, cesium-adsorbed service conditions.

[0028] In some embodiments, in the current-voltage characteristic power generation experiment, the emitter temperature T of the thermionic energy converter is controlled. E The electrode gap d between the receiver and emitter and the plasma vapor pressure P Cs Keep it constant, only change the receiving electrode temperature T C This was done to test and obtain volt-ampere characteristic power generation data at different receiving electrode temperatures. For example, the receiving electrode temperature T... C The range of K can be from 800K to 1200K.

[0029] In some embodiments, a tungsten electrode can be used as the emitter and a niobium-zirconium electrode as the receiver. During the current-voltage characteristic power generation experiment, the emitter and receiver are installed in a heating chamber. After evacuating and preheating the heating chamber, the two electrodes are gradually heated until they reach the required experimental temperature. Then, cesium vapor is introduced into the heating chamber, and after a period of equilibration, the power generation test is performed. During the power generation test, the current magnitude is controlled and the voltage data is measured; for example, an electronic load can be used to control the current magnitude to obtain the current-voltage characteristic power generation data. Based on this data, a current-voltage characteristic curve can be plotted.

[0030] Furthermore, after obtaining the current-voltage characteristic curve at a certain receiving electrode temperature, the emitter temperature is kept constant, and the receiving electrode temperature is controlled to decrease along the gradient to test the current-voltage characteristic curves at different receiving electrode temperatures. In some embodiments, helium gas can be introduced into the rear end of the receiving electrode, and the temperature gradient of the receiving electrode can be controlled by adjusting the helium gas pressure.

[0031] Figure 3 The diagram illustrates the current-voltage characteristic curves of a W-Nb / Zr electrode pair under different receiving electrode temperatures according to an embodiment of the present invention. In step S20, the voltage data corresponding to the target current, i.e., the effective voltage U, can be extracted from the current-voltage characteristic curves. The target current can be set according to actual conditions. By setting different target currents, the work function of the receiving electrode under different target currents can be calculated.

[0032] With target current j e =4A / cm 2 For example, the effective voltage corresponding to the target current is extracted from the volt-ampere characteristic curve, as shown in Table 1. Since the volt-ampere characteristic power generation data is discrete data, in this embodiment, an interpolation method can be used to obtain the effective voltage corresponding to the target current from the volt-ampere characteristic curve.

[0033]

[0034] Table 1 shows the target current of 4 A / cm at different receiving electrode temperatures. 2 The effective voltage corresponding to the time

[0035] In some embodiments, in step S30, according to different receiving electrode temperatures T C The corresponding effective voltage U and emitter temperature T E Electrode gap d and plasma vapor pressure P Cs Calculate the receiver electrode at different receiver electrode temperatures T under the target current. C Work function under During the calculation, the emitter temperature T E Electrode gap d and plasma vapor pressure P Cs By using the values ​​set in the current-voltage characteristic power generation experiment, the work function of the receiving electrode can be calculated based on the experimental data obtained from the current-voltage characteristic power generation experiment and the parameters set in the experiment.

[0036] In some embodiments, the work function of the receiving electrode can be calculated based on the energy balance equation of the thermionic energy converter. E And the energy Q carried by the receiving electron. C The difference, i.e., P = Q E -Q C Electrons escaping from the emitter carry away heat; the heat carried away by electrons from the emitter at a unit current density is defined as the electron cooling rate q. E (Dimensionless, V); Correspondingly, electrons bring heat when they reach the receiving electrode. The heat brought in by electrons when they reach the receiving electrode at a unit current density is defined as the electron heating amount q. C (Dimensionless). The energy balance equations for the thermionic energy converter are shown in expressions (1) to (3) below.

[0037]

[0038]

[0039] U = q E -q C (3)

[0040] in, The effective work function of the emitter; is the effective work function of the receiving electrode; k is the Boltzmann constant; e is the electron constant. For example... Figure 4 As shown, T E T is the emitter temperature. C T represents the receiving electrode temperature. eE T represents the electron temperature at the plasma boundary near the emitter, i.e., the near-emitter plasma boundary temperature; eC Let J be the electron temperature at the plasma boundary near the receiver electrode, i.e., the near-receiver plasma boundary temperature; J is defined as... E =j E / j、J C =j C / j、J iE =j iE / j、J iC =j iC / j, J E J C J iE and J iC All are dimensionless currents; j E It is the emission current at the emitter surface, j C It is the emission current on the surface of the receiving electrode, j iE j iC , respectively, are the absolute ion currents on the emitter and receiver surfaces, and j is the actual current density; These are the potentials at the emitter and receiver surfaces, respectively, and their relationship to the plasma ionization, average plasma potential, and T. eE T eC It is related to the size.

[0041] Based on the energy flow calorimetry experiment and theoretical analysis of the emission behavior of the electron electrode surface in the thermionic energy converter, it can be known that q E Independent of receiver electrode temperature T C The changes in T and its surface electron emission behavior, and due to the balance between the heat conduction energy of the electron gas at the receiving end and the heating of the electrons emitted by the receiving electrode, C Changes in the near-receiving electrode plasma boundary T eC It has no effect, which can also be verified according to the plasma transport equation.

[0042] In this embodiment, based on the energy balance equation and combined with the current-voltage characteristic curve data of the thermionic energy converter, the temperature T near the plasma boundary can be calculated. eC and electron cooling amount q E This enables real-time, online calculation of the effective work function of the receiving electrode material under service conditions.

[0043] In some embodiments, step S30 includes: step S31, according to different receiving electrode temperatures T C Calculate the electron cooling q of the emitter of the thermionic energy converter based on the corresponding effective voltage U. E and the near-receiving electrode plasma boundary temperature T eC Step S32, based on the electronic cooling amount q E Near-receiving electrode plasma boundary temperature T eC Calculate the receiver electrode at different receiver electrode temperatures T under the target current. C Work function under

[0044] In step S32, the electron cooling amount q can be determined based on the Richardson emission equation and the energy balance equation of the thermionic energy converter. E Near-receiving electrode plasma boundary temperature T eC Calculate the receiver electrode at different receiver electrode temperatures T under the target current. C Work function under

[0045] According to the Richardson-Dushman equation, the dimensionless emission current of the receiver can be obtained as:

[0046]

[0047] Where A0 is Richardson's constant; D C denoted as the electron transparency coefficient of the receiving electrode surface; j represents the actual current density in the current-voltage characteristic power generation experiment.

[0048] Based on expression (4) and the energy balance equation, the work function of the receiving electrode can be obtained as follows:

[0049]

[0050] Among them, U(T) C ) and T C q can be obtained through a current-voltage characteristic power generation experiment. E and T eC It is an unknown quantity. In step S32, if q is obtained... E and T eC The work function of the receiver at different receiver temperatures can then be calculated.

[0051] It should be noted that, since the receiving electrode temperature is not particularly high, the effect of the ion current on the effective voltage is very small. Therefore, J in expression (5) ic and The value of is extremely small, and it can be approximated during calculation. For example, it can be... Set it to a constant, for example, 0.02 eV.

[0052] Furthermore, due to the receiving electrode temperature T C The change does not affect q E ,Right now After differentiating expression (1), we get the following expression (6).

[0053]

[0054] Under otherwise constant conditions, as the temperature of the receiving electrode increases, the effective voltage corresponding to the same target current first increases and then decreases, i.e., the effective voltage varies with the temperature of the receiving electrode, as shown by the curve U(T). C There exists an extreme point, at which expression (6) contains an extreme point.

[0055] U(T) can be determined based on expressions (4) and (6). C The dimensionless emission current at the receiving electrode at the extreme point of the curve is:

[0056]

[0057] Substituting expressions (7) and (4) into the energy balance equation, we can obtain U(T) C The effective voltage at the extreme point of the curve, i.e., the receiver temperature, is equal to the receiver temperature at the extreme point. When the effective voltage is:

[0058]

[0059] Furthermore, due to T eC With T C The change is irrelevant; apply expression (7) to T again. C Taking the first derivative yields expression (9).

[0060]

[0061] It can be seen that there are 3 unknowns in expressions (8) and (9), namely... T eC and q E Therefore, it can be determined that Then, T is determined based on expressions (8) and (9). eC and q E .

[0062] In some embodiments, if it is known The U(T) obtained from the current-voltage characteristic power generation experiment can be used to test the current-voltage characteristic. C The curve is processed to determine Corresponding to Furthermore, based on the effective voltage corresponding to different receiver electrode temperatures under the target current and the above expressions (8) and (9), the following can be determined: T eC and q E .

[0063] Specifically, in order to determine TeC and q E ,like Figure 5 As shown, step S31 includes steps S311 to S316.

[0064] Step S311: Set the initial value of the electronic cooling amount to q. E0 .

[0065] Step S312, based on the initial value q of the electronic cooling amount E0 Temperature T of each receiving electrode C And its corresponding effective voltage U, determine the receiving electrode temperature at the extreme point.

[0066] Step S313, based on the receiving electrode temperature at the extreme point and its corresponding effective voltage U opt Determine the electron cooling amount q after iteration. E and the near-receiving electrode plasma boundary temperature T eC .

[0067] Step S314: Determine the electron cooling amount q after iteration. E Does it meet the pre-set requirements?

[0068] Step S315, when the electron cooling amount q after iteration E When the predetermined requirements are met, the iteration stops, and the electron cooling amount q is obtained. E and the near-receiving electrode plasma boundary temperature T eC .

[0069] Step S316, when the electron cooling amount q after iteration E If the predetermined requirements are not met, the iterative electron cooling amount q will be... E Set as initial value q E0 Repeat steps S312 to S314.

[0070] In this embodiment, the electron cooling amount q is continuously optimized through iterative calculation. E Finally, the electron cooling amount q that meets the predetermined requirements is obtained. E and the near-receiving electrode plasma boundary temperature T eC Therefore, the work function of the receiving electrode at different receiving electrode temperatures can be calculated using expression (5).

[0071] In some embodiments, step S312 includes: based on an initial value q of the electronic cooling amount E0 Temperature T of each receiving electrode C And its corresponding effective voltage U, determine the temperature T of each receiving electrode. C The corresponding assumed value of the near-receiving electrode plasma boundary temperature Determine the values ​​of each hypothesis minimum value Minimum value The corresponding receiving electrode temperature T C The receiving electrode temperature at the extreme point

[0072] In this embodiment, assuming that the U(T) obtained from the current-voltage characteristic power generation experiment... C Every point on the curve satisfies Then a value can be calculated for each point. The following expressions (10) and (11) can be obtained.

[0073]

[0074]

[0075] However, in fact only hour, For any T C All assume that it is The corresponding U = U opt A series of... can be determined. In a physical sense, With T eC The difference reflects the receiving electrode temperature T C and The deviation between them, when the deviation is minimum, T eC equal The corresponding T C equal

[0076] In each iteration, in step S312, it can be assumed that the temperature T of each receiving electrode in the current-voltage characteristic power generation experiment is... C for Then it can be based on the initial value q of the electronic cooling amount E0 Receiver electrode temperature T C The effective voltage U and the temperature T of each receiving electrode are calculated using expression (10). C The corresponding assumed value of the near-receiving electrode plasma boundary temperature Then, the assumed values ​​of the plasma boundary temperature near each receiving electrode are compared. The minimum value is set as the near-receiver plasma boundary temperature T. eC The receiving electrode temperature corresponding to the minimum value is set as the receiving electrode temperature at the extreme point.

[0077] In some embodiments, step S313 includes: based on the receiving electrode temperature at the extreme point. and its corresponding effective voltage U opt Determine the effective voltage U opt At the receiving electrode temperature Differential value at point According to the differential value and the receiving electrode temperature at the extreme point Calculate the near-receiver plasma boundary temperature T eC According to the near-receiving electrode plasma boundary temperature T eC Receiver temperature at extreme points and its corresponding effective voltage U opt Calculate the electron cooling amount q after iteration. E .

[0078] In each iteration, when the receiver temperature at the extreme point is determined... Then, the electron cooling amount q can be recalculated using expression (9). E Among them, the differential value The extreme temperature can be received at the extreme point determined in step S312. and its corresponding effective voltage U opt To calculate. In some embodiments, U can be approximated using the finite difference method. Differential value at point In determining Differential value at point Then, the near-receiver plasma boundary temperature T can be calculated using expression (9). eC The plasma boundary temperature T near the receiving electrode is then... eC Receiver temperature at extreme points and its corresponding effective voltage U opt Substituting into expression (8), calculate the electron cooling amount q. E Thus, the final electron cooling amount q is obtained. E Or for the initial value q E0 Perform iterations.

[0079] In some embodiments, the predetermined requirement includes: the iterative electron cooling amount q E With the initial value q of the electron cooling amount E0 The error between them is less than or equal to the error threshold. The error threshold can be set according to actual needs; for example, the error threshold can be 0.02.

[0080] Specifically, after step S313, the electron cooling amount q after the iteration is determined. E Whether the predetermined requirements are met, i.e., comparing the electron cooling amount q after the iteration. E With initial value q E0 For example, if |q E -q E0 If |≤0.02, it indicates that the electron cooling amount q after iteration E If the predetermined requirements are met, the process can proceed to step S315, stop the iteration, and output the electron cooling amount q obtained in step S313. E and the near-receiving electrode plasma boundary temperature T eC If |q E -q E0 If |>0.02, it indicates that the electron cooling amount q after iteration is... E If the predetermined requirements are not met, the process can proceed to step S316 to adjust the iterative electron cooling amount q. E Set as initial value q E0 Repeat steps S312 to S314 until the electron cooling amount q after iteration is reached. E The pre-order requirements have been met.

[0081] Furthermore, in some embodiments, a calculation model of the receiving electrode's work function can be established, and step S30 can be implemented through this calculation model. By inputting the experimental data obtained in steps S10 and S20, as well as the power generation condition parameters set in the experiment, into the calculation model, the work function of the receiving electrode can be calculated. This method is convenient to use and saves costs and manpower.

[0082] For example, the data shown in Table 1, the experimental parameters (emitter temperature, electrode gap, cesium vapor pressure) in the current-voltage characteristic experiment, as well as the error threshold and initial value q are used. E0 When input into the computational model, the following can be calculated: Sure q E = 2.4491V. The effective work function near the optimal operating point of 1000K is 1.541eV, while the result of Nb / Zr at this temperature in the literature is 1.570eV, with a relative error of 1.85%, which is small. Moreover, the trend of the work function is to decrease first and then increase, which is consistent with the literature, indicating that the measurement method in the embodiment of the present invention can more accurately determine the work function of the receiving electrode under near-real service conditions.

[0083] The measurement method described in this invention combines the theoretical basis of the thermionic energy converter under arc conditions with the functional characteristics of the flat plate electrode thermionic experimental device. It can calculate the work function of the receiving electrode material of the thermionic energy converter in real time online. It is convenient to use and can obtain the work function under different receiving electrode temperatures and different target currents. The data obtained is comprehensive and can reflect the work function under real service conditions.

[0084] Regarding the embodiments of the present invention, it should also be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0085] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for measuring the work function of the receiving pole of a thermionic energy converter, characterized in that, The thermionic energy converter includes an emitter, a receiver, and plasma, wherein the plasma is disposed between the emitter and the receiver, and electrons emitted by the emitter reach the receiver via the plasma; the method includes: Step S10: Obtain the electrode material of the receiving electrode at different receiving electrode temperatures. The current-voltage characteristic curve is shown below. Step S20: Based on the current-voltage characteristic curve, determine the temperature at different receiving electrode temperatures. Effective voltage corresponding to the target current ; Step S30, according to different receiving electrode temperatures The corresponding effective voltage Calculate the receiving electrode at different receiving electrode temperatures under the target current. Work function under ; Step S30 includes: Step S31, according to different receiving electrode temperatures The corresponding effective voltage Calculate the electron cooling amount of the emitter. and the near-receiving electrode plasma boundary temperature ; Step S32, based on the electronic cooling amount and the near-receiving electrode plasma boundary temperature Calculate the receiving electrode at different receiving electrode temperatures under the target current. Work function under ; Step S31 includes: Step S311: Set the initial value of the electronic cooling amount to [value]. ; Step S312, based on the initial value of the electronic cooling amount Temperature of each receiving electrode And its corresponding effective voltage U, determine the receiver temperature at the extreme point of the effective voltage versus receiver temperature curve. ; Step S313, based on the receiving electrode temperature at the extreme point. and its corresponding effective voltage Determine the electron cooling amount after iteration. and the near-receiving electrode plasma boundary temperature ; Step S314: Determine the electron cooling amount after iteration. Does it meet the pre-reservation requirements? Step S315, when the electron cooling amount after iteration When the predetermined requirements are met, the iteration stops, and the electron cooling amount is obtained. and the near-receiving electrode plasma boundary temperature ; Step S316, when the electron cooling amount after iteration If the predetermined requirements are not met, the iteratively adjusted electron cooling amount will be... Set to the initial value Repeat steps S312 to S314.

2. The method according to claim 1, characterized in that, Step S312 includes: Based on the initial value of the electronic cooling amount Temperature of each receiving electrode The temperature of each receiving electrode is determined by its corresponding effective voltage U. The corresponding assumed value of the near-receiver plasma boundary temperature ; Determine each of the stated hypothetical values minimum value The minimum value Corresponding receiving electrode temperature The receiving electrode temperature at the extreme point. .

3. The method according to claim 1, characterized in that, Step S313 includes: Based on the receiving electrode temperature at the extreme point and its corresponding effective voltage Determine the effective voltage At the receiving electrode temperature Differential value at point ; According to the differential value and the receiving electrode temperature at the extreme point Calculate the near-receiving electrode plasma boundary temperature. ; Based on the near-receiving electrode plasma boundary temperature The receiving electrode temperature at the extreme point and its corresponding effective voltage Calculate the electron cooling amount after iteration .

4. The method according to claim 1, characterized in that, The predetermined requirements include: The iterative electron cooling amount The initial value of the electronic cooling amount The error between them is less than or equal to the error threshold.

5. The method according to claim 1, characterized in that, In step S32, based on the Richardson emission equation and the energy balance equation of the thermionic energy converter, according to the electron cooling amount Near-receiving electrode plasma boundary temperature and the receiving electrode temperature at the extreme point Calculate the receiving electrode at different receiving electrode temperatures under the target current. Work function under .

6. The method according to claim 1, characterized in that, Step S10 includes: A current-voltage characteristic power generation experiment was conducted on the aforementioned thermionic energy converter at different receiving electrode temperatures. Tests were conducted to obtain the electrode material of the receiving electrode at different receiving electrode temperatures. The current-voltage characteristic power generation data is as follows; Based on the current-voltage characteristic power generation data, plot the electrode material of the receiving electrode at different receiving electrode temperatures. The current-voltage characteristic curve is shown below.

7. The method according to claim 6, characterized in that, In the current-voltage characteristic power generation experiment, the emitter temperature of the thermionic energy converter, the electrode gap between the receiver and emitter, and the plasma vapor pressure are kept constant.

8. The method according to claim 7, characterized in that, In step S30, according to different receiving electrode temperatures The corresponding effective voltage The emitter temperature, the electrode gap, and the plasma vapor pressure are used to calculate the receiver electrode at different receiver electrode temperatures under the target current. Work function under .

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