Data Acquisition System of Neutral Beam Injector on EAST

In order to supervise the elements of the neutral beam injector (NBI) spatially located at several places, a distributed NBI data acquisition system (NBIDAS) on experimental advanced superconducting tokamak (EAST) is developed in this paper. NBIDAS consists of field instrument and measurement devices, servers and remote data processing terminals. In order to remotely manage and monitor the field devices of the NBI system, a device management client software is also developed as the human–machine interfaces between the field devices and remote system administrators. A control signal acquisition system is developed for diagnosing these generated analog and digital signals from the NBI control system. NBIDAS based on network technologies is capable of extending system functions and upgrading devices. The detail of the architecture and implementation of the NBIDAS on EAST is discussed in the paper.     

Experimental Results of Ion Beam Extraction of High-Current Ion Source for EAST Neutral Beam Injector

The first campaign of ion beam extraction tests are completed for EAST NBI high current ion source. The hydrogen ion beam with beam voltage of 80 keV is extracted from tetrode accelerator system. During the experiment, the characteristics of arc discharge and ion beam extraction are studied. The arc power reaches 120 kW and the extracted ion beam power reaches 3 MW. The relationship of some key parameters of arc and beam are investigated, and the details are described in this paper.     

Development of Distributed Control System for Neutral Beam Injector on EAST

A distributed control system of Neutral Beam Injector(NBI) on the Experimental Advanced Superconducting Tokamak(EAST-NBI) is briefly presented in this paper.The control system is developed in accordance with the experimental operational characteristics of the EASTNBI.The NBI control system(NBICS),which is based on the computer network technologies and classified according to the control levels,consists of three levels:a remote monitoring layer,a server control layer,and a field control layer.The 3-layer architecture is capable of extending the system functions and upgrading devices.The timing system provides the reference clock of the synchronization and interlock for the EAST-NBI system.An interlock system ensures the safety of the experiment operators and field devices.Both of the ion sources of the beamline are designed to operate independently.This lays an important foundation for developing a control system for the second beamline on EAST.Experimental results demonstrate that the NBICS meets functional requirements of the EAST-NBI control,and makes experimental operations visual and automatic.     

A Calculation Model of Beam Angular Divergence for EAST Neutral Beam Injector

Distributed thermocouple measurement will be used on EAST neutral beam injection beam angular divergence measurement. In order to obtain calculation model of beam angular divergence: (1) the structure of accelerating electrodes are analyzed, (2) mathematic derivations of beam intensity distribution for neutral beam is given basing on theory of Gaussian distribution, (3) the processing method of experiment data and selection of algorithm are given. The model could point the way to beam angular divergence measurement of EAST neutral beam injection.     

First Achievement of Plasma Heating for EAST Neutral Beam Injector

As one of the most effective methods for plasma heating,a neutral beam injector(NBI) achieved plasma heating and current driving for the first time in EAST 2014 experimental campaign.According to the research plan of the EAST physics experiment,the first NBI(EASTNBI-1) has been built and become operational in 2014.In this article,the latest experiment results of EAST-NBI-1 are reported as follows:(1) EAST achieves H-mode plasma in the case of NBI heating alone,(2) EAST achieves 22 s long pulse stable H-mode plasma in the case of sinndtaneous NBI and lower hybrid wave(LHW) heating.The measurement data show that the loop voltage decreased and the plasma stored energy increased obviously.The results indicate that EAST-NBI-1 has achieved plasma heating and current driving,and thus lays a foundation for the construction of EAST-NBI-2,which will be built in a few months this year.     

Preliminary Results of Ion Beam Extraction Tests on EAST Neutral Beam Injector

The neutral beam injection (NBI) system is one of the most important auxiliary plasma heating and current driving methods for fusion device.A high power ion beam of 3MW with 80keV beam energy in 0.5s beam duration and a long pulse ion beam of 4s with 50keV beam energy ion beam extraction were achieved on the EAST neutral beam injector on the test-stand.The preliminary results show that the EAST-NBI system was developed successfully on schedule.     

Analysis of MW-scale Beam Extraction of EAST Neutral Beam Injector Test-stand

Neutral beam injection has been recognized as one of the most effective means for plasma heating. The preliminary data of 50 keV, 100 s and 80 keV, 1 s beam extraction have been obtained on the EAST neutral beam injector (NBI) test-stand. In this paper, beam energy distribution deposited on each heat load component and neutral efficiency of EAST-NBI has been measured using water-flow calorimetry and beam divergence angle and perveance have been analyzed according to the data obtained from the thermocouples installed in the calorimeters.     

The Timing System of the Neutral Beam Injector on EAST

In order to synchronize the elements of the EAST Neutral Beam Injector(NBI)spatially located in several places,a distributed Timing System(TS) is developed in this paper.The timing system provides a clock reference for synchronization and an interlock protection of the EAST NBI system.It sends timing signals to field devices,controls the pulse widths of the timing sequences,and provides a sampling clock for the Data Acquisition System(DAS).The timing system also generates analog waveforms to control power supplies and gas supplies according to the operator’s configuration.The timing system is developed on a PXI(PCI extensions for Instrumentation) platform consisting of a Lab VIEW workstation and a timing control terminal.The timing control terminal consists of a timing node and several control interface crates.Two timing nodes are configured in one beam line.Each node is responsible for the timing sequence,analog generation and feedback control for one ion source.The architecture and implementation of the timing system are presented in this paper.     

Water Flow Calorimetry System of EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most effective means of plasma heating. The EAST NBI water flow calorimetry system (WFCS) based on PCI extensions for instrumentation (PXI) was established, it can measure temperature rise and flow rate of cooling water of the heat load components, and achieve beam power distribution and neutralization efficiency. Experimental data obtained from WFCS are feedback of the ion source operation state and direct the operation parameter optimization of the ion source. Experimental results show that the WFCS is stable, reliable, and meet the experimental requirements fully.     

A Calculation Model of Beam Power Based on Thermocouple for EAST Neutral Beam Injector

Beam power measurement usually adopts water flow calorimetry (WFC) for neutral beam injector. In this article a calculation model of beam power for EAST neutral beam injector was given basing on thermocouples installed in the calorimeter plate. In order to obtain calculation model: (1) the heat flux of the surface of beam stopping elements was calculated using heat transfer science, (2) the processing method of data obtained from the thermocouple was given, (3) mathematic derivations of beam power is given basing on theory of Gaussian distribution. The model could point another way to beam power measurement of EAST neutral beam injector besides WFC.     

Achievement of 100 s Long Pulse Neutral Beam Extraction in EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most e®ective means for plasma heating. A 100 s long pulse neutral beam with 30 keV beam energy, 10 A beam current and a 100 s long pulse modulating neutral beam with 50 keV beam energy, 16 A beam current were achieved in the EAST neutral beam injector on the test-stand. The preliminary results suggest that EAST-NBI system initially possess the ability of long pulse beam extraction.     

Analysis of Power Deposition on Heat Load Components for EAST Neutral Beam Injector

Neutral beam injection is recognized as one of the most effective means of plasma heating. The target values of EAST Neutral beam injector (NBI) are beam energy 50–80 keV, injection beam total power 2–4 MW, beam pulse width 10–100 s. The beam power will deposit on the beam collimator due to the beam divergence and it will cause heat damage to heat load components, or even destroy the entire NBI system. In order to decrease the risk, the beam power deposited on heat load components should be assessed. In this article, the percent of power deposition on each heat load components has been calculated using Gaussian beam transmission model. Comparison of the results measured with water flow calorimeter and calculated results shows the beam transmission model has relative good agreement with real distribution. The results can direct the operation parameter optimization of EAST NBI.     

High-Speed Optical Signal Processing System Based on DSP for Neutral Beam Injector on EAST

Neutral Beam Injection (NBI) is one of the main plasma heating methods in nuclear fusion devices. To prevent the device from irreversible damage, all the status signal acquisition and transmission must meet high voltage isolation, fast-reaction and high reliability requirements. DSP performs well at complicated algorithms computing and meets the real-time requirements, but it is poor at parallel processing. FPGA is good at combination logic and sequential logic control. To meet the EAST-NBI control system experimental operational requirements, DSP and FPGA architecture is taken in this design, which converts the optical signal to high-precision analog signal to output. This paper analyzes the requirement of high-speed optical signal processing system based on DSP for EAST-NBI and introduces the detail modules designs, including seven modules: optical signal receiving and conversion interface circuit, FPGA decoding interface circuit, OMAP processing interface circuit, DAC interface circuit, Ethernet interface circuit, serial port interface circuit and amplification interface circuit.     

Gas Flow in the Neutralization Region of EAST Neutral Beam Injector

The gas flow in the neutralization region affects the neutralization efficiency as well as the beam transition efficiency of whole neutral beam injector, which will be applied as a high power auxiliary heating and non-inductive current driver system for the Experimental Advanced Superconducting Tokamak (EAST). The neutralization region of EAST neutral beam injector includes not only the gas cell neutralizer in traditional sense, but also part of the ion source downstream the electrode grid, the gate valve, and the transitional piping and fitting. The gas flow in this neutralization region has been modeled and researched using an adjusted Direct Simulation Monte Carlo code to understand the formation mechanism of gas target thickness, which determines the neutralization efficiency. This paper presents the steady-state, viscous and transition region flowfields, the gas density distribution and the various centerline profiles including Knudsen number, temperature, pressure and axial velocity by injected the deuterium gas from the arc chamber and neutralizer, respectively. The target thickness in the neutralization region as a function of gas inlet quantity is also given in the absence of beam for future operation of EAST neutral beam injector.     

Electrical Parameter Measurement System of the Ion Source for EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most effective means of plasma heating. A virtual instrument (VI) has been designed to provide electrical parameter measurement for the ion source of EAST-NBI. The VI is written using the National Instruments LabVIEW graphical programming language. All data acquisition (DAQ) is accomplished using ADLINK DAQ hardware interface and Task-oriented DAQ Driver. The VI can measure filament voltage, filament current, arc voltage, arc current and accelerating voltage etc. The data obtained from the VI are feedback of the ion source operation state and helpful to direct the operation parameter optimization of the ion source.     

Conceptual Design of Neutral Beam Injection System for EAST

Neutral beam injection (NBI) system with two neutral beam injections will be constructed on the Experimental Advanced Superconducting Tokamak (EAST) in two stages for high power auxiliary plasmas heating and non-inductive current drive. Each NBI can deliver 2～4 MW beam power with 50～80 keV beam energy in 10～100s pulse length. Each elements of the NBI system are presented in this contribution.