Filament Power Supply Research Articles

A Dual-Output Power Supply Integrated High -Voltage Anode Power Supply and Filament Power Supply for Magnetrons

A Dual-Output Power Supply Integrated High -Voltage Anode Power Supply and Filament Power Supply for Magnetrons

Comparative Study of High-Voltage Isolated Filament Power Supply for Driving a High-Power Magnetron

Comparative Study of High-Voltage Isolated Filament Power Supply for Driving a High-Power Magnetron

DCM 직렬 공진형 컨버터 기반의 필라멘트 전원 장치의 설계

For the magnetron, gyrotron and electron beam welder, which is the applications of the technology applying high voltage to thermal electrons, the power supply is required to heat filament for emission of thermal electrons. This paper describes the design of filament power supply, whose maximum output voltage is 17 V and maximum output current is 10 A based on the series resonant converter(SRC) operating in discontinuous conduction mode(DCM). The design and operating characteristics were verified by the PSPICE simulation and experimental results with resistor load. Also experimental results with a simulated load, which simulates characteristic of filament load whose impedance increases with increasing temperature, confirmed characteristics of the current source that has a constant output current on the fluctuated load condition.

Control of the gyrotron filament power supplies for the experimental advanced superconducting tokamak.

The electron cyclotron heating system including four gyrotrons is being developed in the Institute of Plasma Physics, Chinese Academy of Sciences. The filament is an important part of the gyrotron, which is used to heat the cathode. The gyrotron output power can be controlled by adjusting the filament power. We have developed the filament power control and measurement system using Labview. The filament characteristics were tested using this power control system. The test results show that the filament current can be fitted with the e-exponential function of the filament voltage. It can be seen that as the voltage increases, the filament resistance gradually increases. We have developed a new "burst" function to prevent the beam current from dropping too fast, which is conducive to long pulse stable operation of the gyrotrons.

Study on the filament power supply of the 300 keV electron accelerator

This paper describes the study and development of the filament power supply. This locally designed low energy electron accelerator with the present energy of 140 keV will be upgraded to 300 keV. The filaments are used to heating-up and produce the electron. The produced electron will be accelerated through a potential different by a DC High Voltage Power Supply (DCHVPS). Whereby this filament power supply is connected with the DCHVPS, therefore the isolation of high voltage is required. For such purpose, the specifications and the isolation mechanisms of the filament power supply have been identified. As the result, the filament power supply by using an air core transformer has been selected and developed with the required heating power.

Analysis and Design of Filament Power Supply with Voltage-Fed Single-Switch ZVS Inverter

In this paper, an off-line voltage-fed single-switch zero-voltage-switching (ZVS) inverter is analyzed and designed for the filament power supply of cooker magnetrons. Due to the low resistance of cathode filament, an isolation transformer with large turn ratio is used. To obtain the ZVS operation, a parallel-resonant capacitor is connected to the primary of transformer. The capacitor, transformer and filament constitute a parallel resonant tank. Both the transformer leakage inductance and the transistor output capacitance are merged into the resonant tank. The resonant energy provides the ZVS operation of the inverter switch, and the secondary voltage drives the cathode filament. To verify the analysis, a prototype inverter is built and tested. Experimental results validate the circuit design.

A Series Resonant Filament Power Supply with Variable Structure and Oscillation-Free Switching Strategy for High-Voltage Accelerator Application

Filament in a high-voltage accelerator needs to be fed by a power supply (PS) to emit electron beam. Rather than using traditional regulated transformer, power electronics converter is a better solution for such a PS. This letter proposes an optimized power electronics solution for such a PS. The primary side of the PS is placed far away from the filament to facilitate the assembly; and the high-frequency transformer is placed very close to the filament to reduce the conduction loss on the secondary-side wires. The PS is designed as a series resonant converter, so that the parasitic inductances and resistances of the wires, transformer, and filament can be fully utilized as resonant components. The H-bridge with zero-voltage switching is used, so that the thermal problem can be alleviated in the vacuum environment. The H-bridge is proposed to be operated in either half-bridge or full-bridge structure to narrow the switching frequency range. A special switching strategy is also proposed to eliminate the oscillation of voltage and current during structure switching, ensuring the safety operation of the converter and the stable vacuum environment around the filament. The designs are experimentally verified by a prototype.

Instrumentation and control system architecture of ECRH SST1

The Electron Cyclotron Resonance Heating (ECRH) system is an important heating system for the reliable start-up of tokamak. The 42GHz and 82.6GHz Gyrotron based ECRH systems are used in tokomaks SST-1 and Aditya to carry out ECRH related experiments. The Gyrotrons are high power microwave tubes used as a source for ECRH systems. The Gyrotrons need to be handled with optimum care right from the installation to its Full parameter control operation. The Gyrotrons are associated with the subsystems like: High voltage power supplies (Beam voltage and anode voltage), dedicated crowbar system, magnet, filament and ion pump power supplies and cooling system. The other subsystems are transmission line, launcher and dummy load. A dedicated VME based data acquisition & control (DAC) system is developed to operate and control the Gyrotron and its associated sub system. For the safe operation of Gyrotron, two level interlocks with fail-safe logic are developed. Slow signals that are operated in scale of millisecond range are programmed through software and hardware interlock in scale of microsecond range are designed and developed indigenously. Water-cooling and the associated interlock are monitored and control by data logger with independent human machine interface.

Operation and control of high power Gyrotrons for ECRH systems in SST-1 and Aditya

The Electron Cyclotron Resonance Heating (ECRH) system is an important heating system for the reliable start-up of tokamak. The 42GHz and 82.6GHz ECRH systems are used in tokamaks SST-1 and Aditya to carry out ECRH related experiments. The Gyrotrons are high power microwave tubes used as a source for ECRH systems. The Gyrotron is a delicate microwave tube, which deliver megawatt level power at very high voltage ∼40–50kV with the current requirement ∼10A–50A. The Gyrotrons are associated with the subsystems like: High voltage power supplies (Beam voltage and anode voltage), dedicated crowbar system, magnet, filament and ion pump power supplies, cooling, interlocks and a dedicated data acquisition & control (DAC) system. There are two levels of interlocks used for the protection of Gyrotron: fast interlocks (arcing, beam over current, dI/dt, anode voltage and anode over current etc.) operate within 10μs and slow interlocks (cooling, filament, silence of Gyrotron, ion pump and magnet currents) operate within 100ms.Two Gyrotrons (42GHz/500kW/500ms and 82.6GHz/200kW/1000s) have been commissioned on dummy load for full parameters. The 42GHz ECRH system has been integrated with SST-1 & Aditya tokamak and various experiments have been carried out related to ECRH assisted breakdown and start-up of tokamak at fundamental and second harmonic. These Gyrotrons are operated with VME based data acquisition and control (DAC) system. The DAC system is capable to acquire 64 digital and 32 analog signals. The system is used to monitor & acquire the data and also used for slow interlocks for the protection of Gyrotron. The data acquired from the system are stored online on VME system and after the shot stored in a file in binary format. The MDSPlus, a set of software tools has been used for data visualization & management for after shot analysis.

Design of the klystron filament power supply control system for EAST LHCD

A filament is a critical component of the klystron used to heat the cathode. There are totally 44 klystrons in experimental advanced superconducting tokamak (EAST) lower hybrid current drive (LHCD) systems. All klystron filaments are powered by AC power suppliers through isolated transformers. In order to achieve better klystron preheat, a klystron filament power supply control system is designed to obtain the automatic control of all filament power suppliers. Klystron filament current is measured by PLC and the interlock between filament current and klystron high voltage system is also implemented. This design has already been deployed in two LHCD systems and proves feasible completely.

Process automation system for integration and operation of Large Volume Plasma Device

Large Volume Plasma Device (LVPD) has been successfully contributing towards understanding of the plasma turbulence driven by Electron Temperature Gradient (ETG), considered as a major contributor for the plasma loss in the fusion devices. Large size of the device imposes certain difficulties in the operation, such as access of the diagnostics, manual control of subsystems and large number of signals monitoring etc. To achieve integrated operation of the machine, automation is essential for the enhanced performance and operational efficiency. Recently, the machine is undergoing major upgradation for the new physics experiments. The new operation and control system consists of following: (1) PXIe based fast data acquisition system for the equipped diagnostics; (2) Modbus based Process Automation System (PAS) for the subsystem controls and (3) Data Utilization System (DUS) for efficient storage, processing and retrieval of the acquired data. In the ongoing development, data flow model of the machine’s operation has been developed. As a proof of concept, following two subsystems have been successfully integrated: (1) Filament Power Supply (FPS) for the heating of W- filaments based plasma source and (2) Probe Positioning System (PPS) for control of 12 number of linear probe drives for a travel length of 100cm. The process model of the vacuum production system has been prepared and validated against acquired pressure data. In the next upgrade, all the subsystems of the machine will be integrated in a systematic manner. The automation backbone is based on 4-wire multi-drop serial interface (RS485) using Modbus communication protocol. Software is developed on LabVIEW platform using NI-Modbus library and tested for the standalone and integrated operation mode of integrated subsystems. The paper discusses the schema of automation, development of software, comparison of modeling results of vacuum production process with actual pump down characteristic and integration results of the FPS and PPS.

Power supply design for the filament of the high-voltage electron accelerator

The filament is a key component for the electron emission in the high-voltage electron accelerator. In order to guarantee the stability of the beam intensity and ensure the proper functioning for the power supply in the airtight steel barrel, an efficient filament power supply under accurate control is required. The paper, based on the dual-switch forward converter and synchronous rectification technology, puts forward a prototype of power supply design for the filament of the high-voltage accelerator. The simulation is conducted with MATLAB-Simulink on the main topology and the control method. Loss analysis and thermal analysis are evaluated using the FEA method. Tests show that in this prototype, the accuracy of current control is higher than 97.5%, and the efficiency of the power supply reaches 87.8% when the output current is 40A.

A 100 kW high voltage power supply for dual energy computer tomography applications

Dual energy X-ray computer tomography (CT) offers enhanced imaging and reduced radiation dose. A conventional technique is using two tubes, each energized by its high voltage power supply (HVPS) at different voltage levels. This approach is straightforward but costly. An alternative is using a single tube fed by an HVPS capable of generating these same voltages with fast transitions from one state to another. A conventional HVPS with exceptionally fast dynamics is less costly than a modulator employing a set of HV switches. Such an HVPS is described in this paper. Key technology includes an all-solid-state modular IGBT-based HV converter with energy-dosing inverters operating at up to 70 kHz. The inverters’ output voltages are phase-shifted, which yields low ripple and fast risetime combined with low stored energy. Controls provide standard operating features and means of communicating with the outside world. Digital processing enables predictive control for generating clean transitions from one state to another in a wide range of load/line conditions. The HVPS incorporates also two filament power supplies and a high-speed starter. Results of extensive testing with both resistive loads and X-ray tubes are presented. The developed techniques can also be used in other applications requiring low-cost generation of high-power HV pulses submillisecond- to many seconds-long.

Power supply system for KSTAR neutral beam injector

The power supply system in KSTAR neutral beam injector consists of low voltage and high current DC power supplies for plasma generator of ion source and high voltage and high current DC power supply for accelerator grid system. The arc discharge is initiated by an arc power supply supplying the arc voltage between the chamber wall and 12 filaments which are heated by individual filament power supply. The negative output of arc power supply is common to each positive output of 12 filament power supplies. To interrupt the arc discharging for the fault condition of the arc current unbalance, DCCT current monitor is placed at the positive output cable of the filament power supply. The plasma grid (G1) power supply has the maximum capability of 120kV/70A which consists of low voltage regulator with IGBT-switched chopper array system for the voltage control in unit of 600V and the high voltage rectified transformers to supply DC voltage of 20kV, 30kV, and 50kV. The output voltage of the G1 power supply is also connected to the input of the voltage divider system which supplies the gradient voltage to the gradient grid (G2) in the range of 80–90% of G1 voltage by changing tap of winding resistors in unit of 1%. The charged G1 voltage is turned on and off by the high voltage switch (HVS) system consisting of MOSFET fast semiconductor switches which can immediately be opened less than 1μs when the ion source grid breakdown occurs. The decelerating grid (G3) power supply is inverter system using capacitor-charge power supply to supply maximum −5kV/5A. The important component in power supply system is the surge absorber near the ion source to limit the arc energy deposited to accelerator grid. This paper presents configuration and features of power supply system, main controller, and interlock system of KSTAR NBI.

Filament Power Supply for Electron Beam Welding Machine

This paper describes the design of a 255-W (17 $\hbox{V}_{\rm rms}$ , 15 $\hbox{A}_{\rm rms} $ ) filament power supply for a 15-kW electron beam welding (EBW) machine. Simulations and results are also included. The filament of the EBW machine consists of a wire, which is heated by the current flowing through it. Although the filament power supply voltage is low (around 17 V) , it is not grounded. In fact, it is displaced $-$ 60 kV dc with respect to ground. Hence, the filament power supply has to be properly isolated. On the other hand, a well-regulated filament power supply is essential for maintaining the stability of the cathode temperature and, consequentially, the lifetime of the filament. In this way, a control method based on the primary voltage is presented, avoiding any feedback loop from the secondary side. The design process and the simulation and experimental results are included in order to verify the control strategy proposed.

Control and Design of a Arc Power Supply for KSTAR's the Neutral Beam Injection

The neutral beam injection generate ultra-high temperature energy in the tokamak of nuclear fusion. The neutral beam injection make up arc power supply, filament power supply and acceleration & deceleration power supply. The arc power supply has characteristics of low voltage and high current. Arc power supply generate arc through constant output of voltage and current. So this paper proposed suitable buck converter for low voltage and high current. The proposed buck converter used parallel switch because it can be increased capacity and decrease conduction loss. When an arc generated, the neutral beam injection chamber occur high voltage. And it will break output capacitor of buck converter. Therefore the output capacitor was removed in the proposed converter. Thus the proposed converter should be designed for the characteristics of low voltage and high current. Also, the arc power supply should be guaranteed for system stability. The proposed parallel buck converter enables the system stability of the divided low output voltage and high current. The proposed converter with constant output be the most important design of the output inductor. In this paper, designed arc power supply verified operation of system and stability through simulation and prototype. After it is applied to the 288[kW] arc power supply for neutral beam injection.

Alternative Technique of Inverter Power Source Synchronization

In devices synchronized with electric mains and sensitive to interference (particularly to an inverter power source) it is expedient to also synchronize the power source. The paper describes a method of synchronizing the inverter power supply with the mains. The general aspects of the method are discussed in detail, and possible hardware implementations are considered. External factors and internal parameters affecting the quality of synchronization are analyzed. The results of practical implementation of this method for synchronization of klystron filament power supply are presented

Development of Cathode Filament Power Supply for EBW Based on ARM

The electron beam welding has high energy density, and has been widely applied in air space, the car and shipping industry. Traditional electron beam welding machine power supply system adopts the technology of the power frequency or medium frequency, with high volume, low efficiency and poor stability of electron beam. I put forward a digital filament power control scheme based on STM32, and introduce the hardware and software implementation method in detail. Experiments show that it can realize soft-start and soft-down process, and also be quickly identified and promptly forbid the output when filament fracture, which realize the intellectualization of filament power supply.

SYNCHRONOUS FLYBACK CONVERTER WITH SYNCHRONOUS BUCK POST REGULATOR

In general, conventional converter is used for converting the power level from one stage to another. But conventional type of converter has slightly more power losses & voltage drop, so efficiency is very sensitive for the low voltage specification and also cooling of dissipative elements floating at higher voltages is a difficult task. So high efficient scheme of synchronous flyback converter with synchronous buck post regulator was approached and low voltage drop, less power losses & very high efficiency was achieved. Where the secondary side of flyback converter including Synchronous buck post regulator floats on the very high voltage line (i.e. 10kV) for the Filament power supply heats the cathode to required temperature to emit electrons in TWT. Filament Power supply based on the Fly back Converter topology which is operated at 100 KHz in CCM mode The Pulse width modulation technique is used to maintain the voltage at desired value using IC. The Post regulator using Synchronous buck topology is implemented for regulating the output voltage of synchronous flyback converter (9.5V DC) to Regulated 6.3V @ 3.3A DC.

DESIGN & ANALYSIS OF FLY BACK CONVERTER FOR GRID & FILAMENT POWER SUPPLIES OF TRAVELLING WAVE TUBE

In High Power Pulsed Radar Transmitters the gridded TWT are used and consists of floating deck modulator unit which houses the Grid and Filament power supplies. The Grid Control includes the Grid Positive & Grid Negative Power Supplies. The Positive voltage is used to turn on the TWT & Negative voltage is used to operate the TWT in off state. The Filament power supply heats the cathode to required temperature to emit electrons. The aim of the project is to design the Grid power supplies and Filament Power supply based on the Fly back Converter topology which is operated at 100 KHz in DCM mode and CCM mode respectively. The Pulse width modulation technique is used to maintain the voltage at desired value using an IC UC1526.The switching device is protected ag