Plasma excitation and maintenance device based on alpha decay ray auxiliary ionization

Abstract

The invention discloses a plasma excitation and maintenance device based on alpha decay ray auxiliary ionization, and belongs to the technical field of plasmas, the plasma excitation and maintenance device comprises a plasma excitation tube, a plasma excitation coil and a plasma detection device, one end of the plasma excitation tube is connected with working gas, the other end of the plasma excitation tube is open, and the open end is a plasma energy injection end; a radioactive substance is embedded in the inner wall of the plasma excitation tube or the air inlet end of the plasma excitation tube, the radioactive substance is one or a combination of more of americium, plutonium and radium, the radiation intensity of the radioactive substance is 0.1-2000 / mu Ci, the open end of the plasma excitation tube is a gradually-shrunk nozzle, and the diameter of the gradually-shrunk nozzle is 10-20 micrometers. And gas in the plasma excitation tube is ionized by utilizing high-energy rays generated by decay, so that the functions of auxiliary excitation and plasma maintenance are achieved.

Description

Technical Field

[0001] The present invention belongs to the field of plasma technology, and in particular relates to a plasma excitation and maintenance device based on alpha decay ray-assisted ionization. Background Art

[0002] A radio frequency plasma ignition burner is a device that uses a radio frequency electromagnetic field to generate plasma to achieve combustion. Plasma flames can be used to heat powders, particles, and even blocks with special requirements. It is usually used in combustion systems to ignite fuel by generating high-energy plasma, thereby achieving a highly efficient combustion process. The working principle of a radio frequency plasma ignition burner is to use a radio frequency electromagnetic field to excite atoms or molecules in a gas or mixed gas to a high energy level, thereby generating plasma. These plasmas have high energy and can be used to ignite fuel, thereby achieving combustion. Compared to traditional spark plug ignition systems, radio frequency plasma ignition burners can provide faster and more reliable ignition; There are many ways to generate plasma. Among them, the method of generating plasma by exciting gas with a high-frequency electric field has the characteristics of controllable flame beam and rich flame types. However, the high-frequency electric field excitation to generate plasma has the problem of flame ignition and is easily extinguished by disturbance. The main factors causing disturbance include: line voltage fluctuation, inductance fluctuation, and capacitance fluctuation. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a plasma excitation and maintenance device based on α-decay ray-assisted ionization to solve the problem that plasma generated by high-frequency electric field excitation has difficulty in flame ignition and is easily extinguished by disturbance.

[0004] The above technical objectives of the present invention are achieved through the following technical solutions: a plasma excitation and maintenance device based on α-decay ray-assisted ionization, characterized in that it includes: a plasma excitation tube, a plasma excitation coil, and a plasma detection device, wherein one end of the plasma excitation tube is connected to a working gas and the other end is open, and the open end is a plasma energy injection end; Radioactive materials are embedded in the inner wall or air inlet end of the plasma excitation tube, and the high-energy rays generated by their decay are used to ionize the gas in the plasma excitation tube, thereby achieving the purpose of assisting in exciting and maintaining the plasma.

[0005] In the above scenario: The plasma excitation tube is made of high-temperature resistant ceramic material with a ceramic wall thickness greater than 5mm. One end of the plasma excitation tube is the air inlet end, which is provided with a working gas input interface and connected to the gas source generator. The other end of the plasma excitation tube is an open plasma energy injection end, which is used to accelerate the plasma jet and improve energy concentration. A radioactive material carrying structure is provided in the air inlet pipe or inner wall area of ​​the plasma excitation tube for fixing or coating the radioactive material. The plasma excitation coil is tightly wound around the outside of the plasma excitation tube to form a spiral inductor coil. When connected to an external high-frequency power supply, it generates an alternating electromagnetic field inside the tube to excite and maintain the plasma. The plasma detection device is used to detect the ionization degree, temperature distribution and jet morphology of the plasma. The detection signal is transmitted to the control system in real time through the data acquisition system for display.

[0006] Furthermore: the radioactive substance is one or a combination of several elements such as americium, plutonium, radium, etc.

[0007] Furthermore: the radioactive substance is americium.

[0008] Furthermore: the radioactive material is an α-ray emitter.

[0009] Furthermore: the radioactive material is arranged in a manner of coating, embedding, or a combination thereof.

[0010] In the above technical solution: after mixing the radioactive material powder with the high temperature resistant adhesive, the mixture is evenly sprayed on the inner wall of the plasma excitation tube; An annular groove is machined on the inner wall of the air inlet end of the plasma excitation tube, and the radioactive material is embedded in the groove and fixed.

[0011] Furthermore: the radiation intensity of the radioactive substance is 0.1-2000 / μCi.

[0012] In the above technical solution: adjustment is made according to the size of the plasma excitation tube and the flow rate of the working gas.

[0013] Furthermore: the radioactive material is arranged on the inner wall or the air inlet end of the plasma excitation tube.

[0014] Furthermore: the open end of the plasma excitation tube is a tapered nozzle.

[0015] Compared with the prior art, the present invention has the following advantages: it can greatly simplify the current excitation operation of radio frequency plasma and significantly enhance the stability and anti-disturbance capability of radio frequency plasma. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0017] In the description of the invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end" and the like indicate the orientation or positional relationship based on the orientation or position shown, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0018] In the first embodiment of the present application, a kind of plasma excitation and maintenance device based on α decay ray auxiliary ionization, characterized by comprising: plasma excitation tube, plasma excitation coil and plasma detection device, one end of plasma excitation tube is connected to working gas, the other end is open, and the open end is plasma energy injection end; Radioactive material is embedded in the inner wall of the plasma excitation tube or the gas inlet end of the plasma excitation tube, the radioactive material is one or a combination of several of americium, plutonium and radium, the radiation intensity of the radioactive material is 0.1-2000 / μCi, and the open end of the plasma excitation tube is a tapered nozzle. The high-energy rays generated by the decay ionize the gas in the plasma excitation tube, thereby achieving the functions of auxiliary excitation and maintenance of plasma.

[0019] In the above technical solution, the radioactive material embedded and coated on the inner wall of the plasma excitation tube and the gas inlet end of the plasma excitation tube continuously decays, and the decay releases high-energy α ions. When the working gas is connected from the gas inlet end of the plasma excitation tube and flows through the radioactive source area, the α ions collide with the working gas molecules and ionize. Among them, the α particles directly hit the gas molecules, making their outer electrons escape from the binding, generating free ionization and positive ions. At the same time, the α particles excite the gas molecules to a metastable state, and the excited-state molecules release energy to produce secondary ionization in subsequent collisions. In this process, the α particles generate initial electron-ion pairs, so that the gas in the plasma excitation tube reaches a weak ionization state, reducing the breakdown voltage of the working gas. The plasma excitation coil wound outside the plasma excitation tube is connected to high-frequency alternating current, generating an alternating electromagnetic field in the plasma excitation tube. The seed ionization produced by the pre-ionization accelerates and collides with the neutral gas in the electric field. The working gas is sprayed out of the open end of the plasma excitation tube at high speed, forming a directional plasma jet carrying active particles to act on the target surface. The radioactive material continuously provides background ionization by decay, compensates for the loss of plasma recombination, maintains power balance, avoids plasma extinction, and realizes maintenance under a high-frequency power fluctuation of ±20%.

[0020] In one option, the selected radioactive material is Am-241 with a radiation intensity of 500 / μCi. The breakdown electric field strength of the working gas is significantly reduced, and the high-voltage pulse generator is eliminated.

[0021] By adopting the technical solution of the present invention, the radioactive material to be coated is selected. Specifically, when argon gas flows into the plasma excitation tube from the gas inlet end and passes through the area coated with Am-241, the α ray is about 5×10 5 The electrons collide with argon atoms at a frequency of 10 times per second, generating about 2×10¹² electron-ion pairs per second, causing the gas ionization degree in this area to reach 0.05%. A 13.56MHz, 100W high-frequency current is introduced into the plasma excitation coil, and the induced electric field strength reaches 50V / m. Free electrons are accelerated to a kinetic energy >15eV in the electric field, triggering chain ionization and forming a stable plasma within 30ms. Under the action of gas pressure, the plasma flows toward the open end of the plasma excitation tube and is accelerated by the tapered nozzle to form a plasma jet of 1000m / s. The temperature in the core area is about 6000K. Am-241 continues to decay, replenishing about 3.7×10 6 Even if the power is temporarily reduced to 80W, the ionization degree only decreases by 10%, and the jet stability does not change significantly.

[0022] By adopting the technical solution of the present invention, a radioactive material is selected for embedding, specifically, Ra-226 thin sheets with a purity of 99.9%, a thickness of 0.5 mm, and a radiation intensity of 500 μCi, which are embedded in three annular grooves on the inner wall of the air inlet end. The surface of the grooves is covered with 0.1 mm thick platinum foil to prevent radium oxidation. The working gas is nitrogen with a flow rate of 10 L / min and an air inlet pressure of standard atmospheric pressure 5; High-pressure nitrogen flows into the plasma excitation tube at high speed from the air inlet end, passes through the area where the Ra-226 sheets are embedded, and the Ra-226 sheets release high-energy alpha particles at a rate of about 1.85×10 6 The frequency of ions per second collides with nitrogen molecules to directly ionize and stimulate ionization. Under high pressure, the density of gas molecules is higher, the mean free path of alpha particles is shortened, and the power efficiency is improved. The ionization degree in this area quickly rises to 0.15%; The plasma excitation coil generates an alternating magnetic field in the excitation tube through a 27.12MHz, 300W high-frequency current. According to the law of electromagnetic induction, a vortex electric field is induced. The free electrons generated by pre-ionization are accelerated in the electric field, and their kinetic energy increases rapidly. When they collide with neutral molecules, an avalanche of electricity is triggered. The electron density soars from 10¹³m⁻³ to 10¹ in 30ms. 7 m⁻³, forming a high-density nitrogen plasma. The ionized gas is ejected from the tapered nozzle of the plasma excitation tube under high pressure to form a plasma jet; Ra-226 continues to decay, releasing about 1.85×10 7The ionization particles are continuously supplemented by alpha particles, and the ionization rate of the alpha particles is increased to maintain the ionization degree at 0.1%-0.2%, and the recombination rate is increased by about 3 times at 5 standard atmospheres. The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements without departing from the principles of the present application, and these improvements should also be considered within the protection scope of the present application.

Claims

1. A plasma excitation and maintenance device based on α-decay ray-assisted ionization, characterized in that: include: A plasma excitation tube, a plasma excitation coil and a plasma detection device. One end of the plasma excitation tube is connected to the working gas and the other end is open, and the open end is the plasma energy injection end; Radioactive materials are embedded in the inner wall of the plasma excitation tube, and the high-energy rays generated by their decay are used to ionize the gas in the plasma excitation tube, thereby achieving the purpose of assisting in exciting and maintaining the plasma.

2. The plasma excitation and maintenance device based on α-decay ray-assisted ionization according to claim 1, characterized in that: The radioactive material is one or a combination of americium, plutonium and radium.

3. The plasma excitation and maintenance device based on α-decay ray-assisted ionization according to claim 2, characterized in that: The radioactive material is arranged in a manner of coating, embedding, or a combination thereof.

4. The plasma excitation and maintenance device based on α-decay ray-assisted ionization according to claim 3, characterized in that: The radiation intensity of the radioactive substance is 0.1-2000 / μCi.

5. The plasma excitation and maintenance device based on α-decay ray-assisted ionization according to claim 4, characterized in that: The radioactive material is arranged at the air inlet end of the plasma excitation tube.

6. The plasma excitation and maintenance device based on α-decay ray-assisted ionization according to claim 1, characterized in that: The open end of the plasma excitation tube is a tapered nozzle.

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