35 results about "Plasma current" patented technology

The invention provides a method and a system for measuring plasma current in a quasi-ring symmetrical star simulator, and relates to the technical field of star simulators, and the method comprises the steps: determining a sensor design index according to a bootstrap current simulation calculation result, and converting the design index into an actual arrangement scheme according to an installation environment constraint; all the magnet coils are independently excited in a plasma-free state, wall eddy current interference signals generated by the magnet coils are calibrated, and thus wall eddy current calibration voltage signals are output; a sensor in an actual arrangement scheme is used for synchronously collecting a total original induced voltage signal including plasma current and wall eddy current; an integral voltage signal representing the total current is output; and compensating the integral voltage signal by using the wall eddy current calibration voltage signal, and inverting the final measurement value of the plasma current in the quasi-ring symmetric star simulator. The device and the method have the beneficial effects that the interference of a stray field on a measurement result is weakened, and a high-precision diagnostic tool is provided for the plasma physical research of the star simulator.

A plasma power supply (10) and a control method therefor, and a fusion reaction system. The plasma power supply (10) comprises: a breakdown power supply module (101) and an extraction power supply module (102). The breakdown power supply module (101) is used for: outputting a first voltage to a plasma generator (20) which generates plasma under the application of the first voltage; and when the output voltage is decreased from the first voltage to a second voltage, maintaining the output of the second voltage to the plasma generator (20). The extraction power supply module (102) is used for forming an electric field between the plasma generator (20) and a housing (30) of a nuclear fusion reaction chamber, and when the plasma generator (20) generates the plasma, forming a plasma current between the housing (30) and the plasma generator (20) on the basis of the plasma and the electric field. The plasma power supply (10) allows for direct formation of the plasma current in the nuclear fusion reaction chamber, thereby simplifying the formation process of the plasma current.

A plasma focus system for aneutronic fusion is disclosed that includes an electrode assembly having an inner electrode extending along a pinch axis from a discharge end to a focus end, and an outer electrode surrounding the inner electrode to define a plasma channel for receiving a process gas containing aneutronic fusion fuel. The system also includes a power supply unit for applying a discharge driving signal to the electrodes, which causes the gas to be ionized into a plasma current sheath at the discharge end that flows along the plasma channel to reach the focus end where the sheath collapses toward the pinch axis to form a plasma pinch. The inner electrode has a tapered tip at the focus end that is configured to increase a speed of the sheath sufficiently to reach a pinch temperature high enough for the fuel to undergo aneutronic fusion reactions within the pinch.

The present invention relates to the field of plasma physics technology and discloses a method for evaluating the influence of plasma circumferential rotation on tokamak hybrid operation, comprising: designing the plasma current required for the hybrid operation of the tokamak device based on the parameters of the tokamak device and the auxiliary heating capacity; Ip and vertical field Bt The present invention comprises designing parameters for the neutral beam injection system and the electron cyclotron wave resonance system required for the tokamak's hybrid operation; injecting the initial neutral beam into the tokamak and performing integrated simulation calculations to obtain a first set of operating parameters for the tokamak's hybrid operation; adjusting the torque of the neutral beam injected into the tokamak to calculate a second set of operating parameters for the tokamak's hybrid operation; and analyzing and comparing the first set of operating parameters with the second set of operating parameters. The present invention can independently assess the impact of plasma toroidal rotation on the tokamak's hybrid operation.

The invention provides a plasma current profile distribution reconstruction method and system based on a high-precision magnetic field inclination angle. The method comprises the following steps: injecting a neutral beam to a specified point direction of a plasma core; a plurality of polarizers with different polarization directions are used for receiving polarized light beams transmitted from the plasma direction; measuring the intensity of polarized light penetrating through the polarizers, and calculating the inclination angle of a specified point magnetic field of the plasma core based on the intensity ratio of polarized light corresponding to each polarizer; acquiring magnetic measurement input data; and performing plasma core current profile distribution inversion based on the inclination angle of the magnetic field of the specified point of the plasma core and magnetic measurement input data. The system comprises a high-precision magnetic field inclination angle measurement system, a data acquisition system and a plasma configuration inversion system. By accurately measuring the inclination angle of the plasma core magnetic field, more accurate data support is provided for reconstruction of plasma current profile distribution, feedback control is optimized, and the stability and constraint efficiency of plasma are improved.

The invention discloses a spherical Tokamak device vacuum cavity wall eddy current measuring method and system, and the method comprises the steps: enabling two detection ends of a collector to be connected with the other end of a first sensing ring and the other end of a third sensing ring respectively, electrifying plasma, applying a current to a CS coil, and enabling the CS coil to be connected with the collector; and obtaining the measurement current measured by the collector, obtaining the plasma current in the vacuum cavity wall, and obtaining the size of the eddy current of the vacuum cavity wall of the spherical Tokamak device. According to the invention, the plurality of sensing rings are arranged, the magnetic fields among the plurality of sensing rings are mutually counteracted and the number of turns is adjusted, so that the error in the measurement process is compensated, the interference of CS coil current can be eliminated as much as possible when the eddy current of the vacuum cavity wall of the spherical Tokamak device is measured through the cooperative work of the plurality of sensing rings, and the measurement precision is greatly improved. The problem that a traditional measurement method is low in measurement precision in a narrow space and a strong interference environment is solved.

The invention discloses an underwater plasma arc cutting device for a large-diameter seamless steel pipe. The underwater plasma arc cutting device comprises a water tank, a displacement system, a multi-degree-of-freedom manipulator, a plasma arc cutting system and a visual sensing and control system. A pressure sensor, a temperature sensor, a hydrogen concentration sensor and a carbon monoxide concentration sensor are arranged in the water tank. A supporting rotating mechanism is arranged in the water tank and used for clamping and driving the large-diameter seamless steel pipe to rotate around the axis of the large-diameter seamless steel pipe. The displacement system is arranged on one side of the water tank, and the multi-degree-of-freedom mechanical arm is installed on the displacement system. A cutting torch of the plasma arc cutting system is installed at the output end of the multi-degree-of-freedom mechanical arm and used for extending into the water tank to cut the steel pipe. And the visual sensing and control system is used for monitoring the cutting process in real time and controlling the plasma arc cutting system, the multi-degree-of-freedom manipulator and the supporting and rotating mechanism to move. Parameters such as the cutting torch position, the cutting track, the plasma current, the gas flow and the cutting speed can be dynamically adjusted through the visual sensing and control system.

The invention provides a plasma power supply, a control method thereof and a fusion reaction system. The plasma power supply comprises a breakdown power supply module and a lead-out power supply module. The breakdown power supply module is used for outputting a first voltage to the plasma generator, and the plasma generator generates plasma under the pressurization of the first voltage; under the condition that the output voltage drops from the first voltage to the second voltage, the second voltage is maintained to be output to the plasma generator; the lead-out power supply module is used for forming an electric field between the plasma generator and a shell of the nuclear fusion reaction chamber, and forming plasma current between the shell and the plasma generator based on plasma and the electric field under the condition that the plasma generator generates the plasma; according to the plasma power supply, plasma current can be directly formed in the nuclear fusion reaction chamber, and the forming process of the plasma current is simplified.

The application provides a kind of quasi-ring symmetry star simulator plasma current measurement method and system, it is related to star simulator technical field, including determining sensor design index according to bootstrap current simulation calculation result, and actual arrangement scheme is converted into design index according to installation environment constraint;In the state of no plasma, all magnet coils are excited separately, and the wall eddy current interference signal generated by the magnet coil is calibrated, so as to output the wall eddy current calibration voltage signal;The total original induction voltage signal including plasma current and wall eddy current is synchronously collected by using the sensor in the actual arrangement scheme;Output integral voltage signal representing total current;The integral voltage signal is compensated by using the wall eddy current calibration voltage signal, and the final measurement value of quasi-ring symmetry star simulator plasma current is inverted.The beneficial effects of the application are to weaken the interference of stray field on the measurement results, and to provide a high-precision diagnostic tool for star simulator plasma physics research.

The invention discloses an adjusting system and method for realizing steady-state billion-degree ion temperature, and relates to the technical field of magnetic confinement nuclear fusion, and the system comprises a central control unit, and a neutral beam injection unit, a central spiral pipe and an air supply unit of which the output ends are connected with plasma in a vacuum chamber. The neutral beam injection unit is used for heating high-energy neutral atoms emitted by the plasma; the central spiral tube is used for generating and controlling plasma current; the gas supply unit is used for conveying working gas into the vacuum chamber; and the central control unit can respectively adjust the neutral beam injection unit, the central spiral pipe and the air supply unit so as to obtain the required steady-state ion temperature. By adjusting the beam energy and power of the neutral beam injection unit, the plasma electron density and the current climbing rate, the plasma has very high heating power density, ion energy transportation is reduced, heating efficiency is improved, and therefore the steady-state ion temperature of hundred million degrees is obtained.

The invention provides a plasma current monitoring device for a semiconductor plasma etching cavity, and relates to the field of monitoring of a semiconductor plasma etching process. The plasma flow in the cavity can be measured in real time under the condition that the environment of the cavity is not interfered. The device is composed of a main body substrate, an upper surface sensing layer, a lower surface integration layer and an electromagnetic shielding film covering the surface of the substrate. The upper surface sensing layer comprises a non-contact magneto-impedance effect current sensor network which is arranged in an annular array; the lower surface integration layer comprises a master control acquisition microcontroller circuit, a power supply circuit, a thin film battery, a charging circuit, a real-time communication circuit and a storage module. The device adopts a structure, a size and an impedance design similar to those of an actual process wafer, can simulate a real state of the wafer in a plasma etching process, and acquires a magnetic signal of the substrate in real time in an etching process. The collected magnetic signals are processed and stored under the control of the microcontroller, and are transmitted to an external reading device through the real-time communication circuit. The method has wide applicability, can be compatible with various semiconductor process equipment, and provides a reliable technical means for real-time monitoring and optimization of the plasma etching process.

An existing terahertz detector is slow in response speed and narrow in response spectrum. The terahertz micro-cavity area array detector based on the bias plasma comprises a window and a photosensitive element, the photosensitive element comprises a first micro-cavity plate, a gas cavity layer and a second micro-cavity plate which are connected in sequence, the first micro-cavity plate is provided with a gas filling pipe, the gas filling pipe penetrates through the first micro-cavity plate, and the gas filling pipe is provided with a gas outlet. The gas filling pipe is communicated with the gas cavity layer, a discharge electrode is arranged on the second microcavity plate, the gas cavity layer is connected with a driving circuit through the discharge electrode, and the gas filling pipe is connected with a gas filling device. The terahertz detector has a spectral imaging function, adopts the principle that terahertz enters a gas cavity layer and the state of plasma changes, realizes detection of terahertz waves, can obtain information such as polarization and intensity of the terahertz waves, can solve the problems that an existing terahertz detector is low in response speed and narrow in response spectrum, is used for hidden target imaging, and has a wide application prospect.

The invention relates to the technical field of plasma current driving, in particular to a TE01 mode transmission elbow structure and an LHCD system. The elbow structure comprises a transition section and an elbow section, the whole transition section is of a circular barrel structure, and a plurality of steps are constructed in the transition section to enable the transition section to form a multi-diameter hole section structure, namely, an inner hole of the transition section has a plurality of hole diameters; the two elbow sections are connected end to end, the free ends of the two elbow sections are connected with a transition section, the bending angle of each elbow section is 45 degrees so that the two elbow sections can form a right-angle turning structure, a plurality of annular grooves are formed in the inner wall of each elbow section, and the annular grooves are distributed in the extending direction of the elbow sections at intervals. According to the invention, the high transmission rate of the TE01 mode can be ensured in a low-frequency environment.

The invention discloses a Tokamak device plasma discharge starting method and system, and relates to the technical field of magnetic confinement fusion. The method comprises the following steps: generating initial plasma through the plasma pre-ionization system; the neutral beam injection system injects neutral particles into the initial plasma, and the injection energy is dynamically adjusted according to the plasma density monitored in real time; the electron cyclotron wave heating system injects microwave energy to drive electrons to generate plasma current; the diagnosis system monitors plasma parameters and neutral beam penetration depth in real time, and feeds back the parameters to the injection system and the heating system to adjust the parameters; and after the plasma current reaches the standard and is stable, parameters are optimized to maintain steady-state operation. The system comprises a pre-ionization module, an injection module, a heating module, a diagnosis module and a control module. According to the invention, the volt-second consumption and construction cost are reduced, the starting efficiency and stability are improved, the device is prevented from being damaged, and various magnetic confinement fusion devices are adapted.

The application discloses a kind of spherical tokamak's equilibrium field power supply, equilibrium power supply method, comprising: constant current source I3 with equilibrium field coil electric connection;Two groups of capacitor banks are respectively connected with equilibrium field coil, for supplying equilibrium field coil a steady-state low-level or high-level current balance high plasma current;Two groups of charge-discharge circuits are respectively connected with two groups of capacitor banks.Based on the equilibrium field power supply of spherical tokamak, the equilibrium power supply method of two groups of capacitors is used to supply power to the equilibrium field coil, so that the low plasma current is balanced by the equilibrium field current provided by constant current source I3, and the high plasma current is balanced by the equilibrium field current provided by two groups of capacitor banks.In the presence of low plasma current, ohmic field is put in, and plasma current is improved to a certain extent.In this way, the problems of limited volt-second product of spherical tokamak ohmic transformer, insufficient coil installation precision and stray field influence caused by vacuum wall eddy current can be compensated.

The application provides a method for preparing single-walled carbon nanotubes by a plasma-assisted chemical vapor deposition method, and relates to the technical field of nanometer material preparation. The method adds controllable plasma current and voltage to the condition of chemical vapor deposition. The plasma promotes the polymerization and growth of carbon atoms by providing a high-energy field and a catalyst activation effect. In the chemical vapor deposition method, iron sulfate and an iron-containing inorganic compound are used in combination. The addition of sulfur can promote the crystallization and arrangement of carbon atoms, and the combination of the two can reduce the surface defects of single-walled carbon nanotubes and reduce the use cost. The method for preparing single-walled carbon nanotubes by the plasma-assisted chemical vapor deposition method can prepare single-walled carbon nanotubes with a Raman G / D ratio of more than 120 while reducing the cost, and large-scale production is realized.

The invention discloses an online quality monitoring system for high-strength steel laser-plasma composite cutting, which belongs to the field of composite cutting online quality monitoring and comprises a data acquisition module, a splash characteristic threshold judgment module, a real-time path comparison module, a process curve comparison module and a bimodal factor diagnosis module. The invention discloses an on-line quality monitoring system for high-strength steel laser-plasma composite cutting, which is characterized in that a data acquisition module acquires laser power, plasma current and other process parameters in real time, and synchronously captures an original image of a cutting area through a three-channel camera; the spatter characteristic threshold determination module establishes a parameter-spatter mapping library and outputs a parameterized threshold; the real-time path comparison module is used for stripping the splashing point and comparing a preset path; the process curve comparison module judges a process abnormal point through the reference arc line; the bimodal factor diagnosis module outputs a quality problem judgment result, real-time monitoring and accurate quality diagnosis in the cutting process are achieved, and it is guaranteed that the cutting quality is stable.

The present application relates to the technical field of controllable nuclear fusion, and particularly relates to a device for controlling energy confinement time by using a limiter bias system. The device comprises a bias electrode head, a soft connection wire connected with the bias electrode head at one end and connected with a bias power supply system of an NCST spherical tokamak device at the other end, and a limiter main body installed on one side of the NCST spherical tokamak device and provided with the bias electrode head for restraining the escaped electrons generated by discharge of the NCST spherical tokamak device. The present application can restrain the escaped electrons generated by discharge of the NCST spherical tokamak device by installing the limiter bias system, improve the energy confinement time parameter of the NCST spherical tokamak device, significantly restrain the plasma instability, and thus increase the plasma current duration and improve the plasma current size.

The application belongs to the technical field of nuclear fusion, and discloses a tokamak plasma vertical displacement event disruption prediction method based on a random forest. The technical scheme comprises the following method steps: S1, obtaining tokamak plasma equilibrium parameters, shape control data and plasma current control data, and cleaning the data; S2, setting different segmentation points according to whether each parameter of each discharge gun is stable or not, and marking them as 0 and 1 respectively; S3, verifying whether each gun has separability by using a t-SNE algorithm. The application inputs different plasma parameters in the tokamak into a machine learning model, sets a threshold value for judgment, and outputs an early warning signal. The method of artificial intelligence is introduced into the EAST tokamak plasma vertical displacement disruption prediction, and the problem of low accuracy of the disruption prediction is solved.

A process chamber and a semiconductor process equipment are disclosed. The process chamber comprises a chamber body having an opening at a top portion thereof, an upper electrode assembly comprising an upper electrode cover plate covering the opening and an electrode assembly disposed at a bottom surface of the upper electrode cover plate, wherein an annular gap is defined between the electrode assembly and a sidewall of the chamber body, and an impedance ring assembly sleeved outside the electrode assembly, wherein the impedance ring assembly comprises dielectric rings and conductive rings which are alternately stacked, and the conductive rings are spaced apart from the electrode assembly and the sidewall of the chamber body. Each of the conductive rings is connected to at least one electrical connector. The electrical connector electrically connects the corresponding conductive ring to the chamber body in a first state, and disconnects the electrical connection between the corresponding conductive ring and the chamber body in a second state. The thickness of the impedance ring assembly can be adjusted without disassembling the upper electrode assembly, so as to adjust the distribution of the plasma current. The operation is convenient, and the production efficiency can be improved.

This invention relates to the interdisciplinary field of quantum computing and nuclear fusion plasma profile reconstruction, and particularly to a tokamak plasma current density reconstruction system based on a coherent Ising machine. The technical solution includes an electromagnetic diagnostic data acquisition unit and a Bayesian posterior modeling processor. The electromagnetic diagnostic data acquisition unit is used to acquire external electromagnetic measurement data of the tokamak device in real time, forming a measurement vector. The Bayesian posterior modeling processor is connected to the electromagnetic diagnostic data acquisition unit and is used to construct a posterior accuracy matrix and a linear term coefficient vector based on a conditional autoregressive prior model and the electromagnetic measurement likelihood probability. This invention organically integrates Bayesian inference modeling, spatial block decomposition, block coordinate descent iterative control, and coherent Ising machine quantum solving, achieving high-precision, rapid reconstruction of the tokamak plasma current density profile with uncertainty quantification within the constraints of existing quantum hardware bit capacity.

A system for a thermonuclear fusion reactor having a feeder configured to introduce a fuel projectile into a contained plasma is described. The system includes one or more lasers for adjusting a propulsion force of the fuel projectile by laser ablation and a controller configured to operate in conjunction with the feeder and the one or more lasers to controllably propel the fuel projectile toward a target location in the contained plasma. This contrasts with existing systems (e.g., fuel projectiles simply follow the magnetic field gradient of the plasma), and may enhance plasma control to achieve improved stability and generation of thermonuclear fusion energy, modulate the fusion rate and the amount of energy generated by the reactor, and improve the performance of the reactor. Plasma current is adjusted to alter the magnetic field and generate electrical power by magnetic induction, and / or have other advantages alone or in combination with existing systems.

Disclosed herein are systems and methods for delivering nitric oxide gas. According to an embodiment, a nitric oxide gas delivery system can include: a first nitric oxide (NO) gas generator, wherein the first NO gas generator includes a plasma chamber enclosing two electrodes separated by a gap; a plurality of port lights surrounding a plurality of corresponding gas outlet ports, wherein each of the port lights are configured to display a color; and an electronic control circuit, wherein the electronic control circuit is configured to enable the plurality of port lights to display the color based on a status of a plasma current across the two electrodes.

A plasma focus system for neutron production is disclosed that includes an electrode assembly having an inner electrode extending along a pinch axis from a discharge end to a focus end, and an outer electrode surrounding the inner electrode to define a plasma channel for receiving a gas containing neutronic fusion fuel. The system also includes a power supply unit for applying a discharge driving signal to the electrodes, which causes the gas to be ionized into a plasma current sheath at the discharge end that flows along the plasma channel to reach the focus end where the sheath collapses toward the pinch axis to form a plasma pinch that generates fusion neutrons. The inner electrode has a tapered tip at the focus end that is configured to increase a speed of the sheath sufficiently to reach a pinch temperature at which the fusion neutrons are predominantly of thermonuclear origin.

A nasal turbinate hemostatic electrode includes a main body, where an end of the main body is fixedly connected to a tip; the tip includes a first electrode and a second electrode; side walls of the first electrode and the second electrode are rounded; the first electrode and the second electrode are spaced apart, and have a same surface area; an end of the main body adjacent to the tip is provided with an outlet hole; the outlet hole is connected to an inlet pipe; the outlet hole is configured to deliver an electrolyte to the tip; and the first electrode and the second electrode are configured to conduct a plasma current in the electrolyte. The nasal turbinate hemostatic electrode prevents the surgical electrode from causing a secondary injury to the patient during an operation process, further improving the use safety of the surgical electrode.

A nasal turbinate hemostatic electrode includes a main body, where an end of the main body is fixedly connected to a tip; the tip includes a first electrode and a second electrode; side walls of the first electrode and the second electrode are rounded; the first electrode and the second electrode are spaced apart, and have a same surface area; an end of the main body adjacent to the tip is provided with an outlet hole; the outlet hole is connected to an inlet pipe; the outlet hole is configured to deliver an electrolyte to the tip; and the first electrode and the second electrode are configured to conduct a plasma current in the electrolyte. The nasal turbinate hemostatic electrode prevents the surgical electrode from causing a secondary injury to the patient during an operation process, further improving the use safety of the surgical electrode.

The invention relates to the technical field of controllable nuclear fusion, in particular to a device for controlling energy constraint time by using a limiter bias system. Comprising a bias electrode tip; one end of the flexible connection wire is connected with the bias electrode tip, and the other end of the flexible connection wire is connected with a bias power supply system of the NCST spherical Tokamak device; the limiter main body is mounted on one side of the NCST spherical Tokamak device, and a bias electrode head is mounted on the limiter main body and used for inhibiting escape electrons generated by discharging of the NCST spherical Tokamak device. By installing the limiter bias system, escape electrons generated by discharging of the NCST spherical Tokamak device are restrained, the energy constraint time parameter of the NCST spherical Tokamak device is improved, plasma instability can be remarkably restrained, then the plasma current duration time is prolonged, and the plasma current size is improved.

The invention relates to the technical field of plasma energy engineering, and discloses a multi-pole magnetic trap magnetic flux distribution prediction method, device and equipment, and the method comprises the steps: constructing a neural network architecture comprising a magnetic flux neural network, a plasma current neural network and a convolution differential operator, and outputting total magnetic flux distribution through the magnetic flux neural network, the plasma current neural network is utilized to obtain the plasma current density from the total magnetic flux distribution and obtain a first constraint condition, meanwhile, a convolution differential operator is combined to obtain a second constraint condition from the total magnetic flux distribution, and a prediction result is determined by comparing convergence errors of the two constraint conditions. Physical constraints are introduced through a convolution differential operator, the problem of large deviation between magnetic flux distribution prediction and reality caused by lack of physical constraints of a common neural network is solved, and meanwhile, through feedback coupling between the magnetic flux neural network and the plasma current neural network, the convergence and stability of the model are improved, and the prediction precision is improved. And the method is closer to the actual multi-pole magnetic trap magnetic flux distribution prediction effect.

The invention discloses a two-dimensional full-wave simulation method considering a polar magnetic field in a finite element code and electronic equipment, and in the full-wave simulation process, the vertical movement effect of parallel wave numbers caused by the existence of the polar magnetic field is considered when plasma current is quite large or a circumferential modulus is relatively small, so that the full-wave simulation efficiency is improved. The method comprises the following steps: firstly, solving a wave equation based on an initial dielectric tensor, determining the distribution of electric fields on Tokamak magnetic surfaces, carrying out wavelet transform on the electric field on each Tokamak magnetic surface to obtain a value of a dominant polar modulus, and correcting a parallel wave number by using the value of the dominant polar modulus; according to the embodiment of the invention, the influence of a polar magnetic field (Tokamak magnetic surface) is considered in the full-wave simulation, and the value of the polar modulus is determined by using wavelet transform, so that the full-wave simulation result is obtained. The time consumption is short, and the simulation result is more accurate.

The application provides a MOS transistor, comprising: a substrate; a P-type well region and an N-type well region which are located in the substrate and are adjacently arranged; a floating gate located on the P-type well region, a bulk terminal located in the P-type well region and a first protection diode, the floating gate is communicated with the N pole of the first protection diode, and the P pole of the first protection diode is communicated with the bulk terminal; a second protection diode located in the N-type well region, the second protection diode is connected with the first protection diode in parallel, the N pole of the first protection diode is communicated with the P pole of the second protection diode, and the P pole of the first protection diode is communicated with the N pole of the second protection diode. If the current generated by the plasma is positive, the current passes through the second protection diode, so that the gate is protected from being damaged by the plasma current. If the current is negative, the current passes through the first protection diode, so that the gate is also protected from being damaged by the plasma current.