Distributed Timing System Of RF-driven Neutral Beam Injection System Based On Precision Time Protocol

Neutral Beam Injection(NBI)has been widely used in magnetically controlled fusion devices as a fusion plasma heating method.In order to achieve high power,long pulse and steady state Neutral Beam Injection heating,Negative ion based Neutral Beam Injection System(NNBI)has become the inevitable choice for the development of Neutral Beam Injection System.A set of high-precision distributed timing synchronization system is needed to complete the corresponding timing synchronization function to ensure the orderly conduct of NNBI experiments and the integrity of experimental data.Based on the specific requirements of NNBI system in timing synchronization,the distributed timing synchronization system of RF ion source is designed and developed in this paper.The synchronous output control of NNBI is analyzed and realized to ensure that each subsystem has the same clock datum and to improve the processing mechanism of asynchronous events such as ignition which cannot be avoided in the process of experiment.The main contents of the system are as follows:(1)In order to realize that all functional hosts of the NNBI system can work under the same clock benchmark and ensure the stable operation of the system,the synchronization module is designed and implemented in detail.Based on IEEE1588 standard Precision Time Protocol(PTP)to implement the site control module of microsecond clock synchronization control,uses the Network Time Protocol(NTP)to control the central control system clock synchronization of millisecond,which is used to prepare for the control of subsequent timing and amplitude,and the analysis of the later data.(2)In order to ensure that each subsystem of the NNBI system can proceed in a complete and orderly manner according to the configuration parameters set by the remote console,the timing control function module is designed and implemented.Transmission of network configuration parameters is completed by Transmission Control Protocol(TCP)and EPICS CA Protocol,and other subsystems are triggered synchronically by network timing trigger.The timing and amplitude output Control of each system is realized by Lab VIEW FPGA module,which is used to determine the specific input time of each system.At the same time,the event trigger mechanism is used to realize the asynchronous processing of special events such as fire,and a series of problems such as data processing of asynchronous events are solved.(3)Design the system test scheme according to the system functional requirements to ensure the feasibility and reliability of the system operation.This module verifies the system by measuring the synchronization error magnitude of the field control system and the central control system,system signal output,system trigger accuracy,asynchronous event response test and other performance indicators,so as to ensure that the system can meet the timing synchronization requirements of the NNBI system.The experimental results show that the distributed timing synchronization system designed and developed in this paper achieves the timing control and clock unification function of the NNBI timing system,solves the timing delay problem caused by the inconsistent clocks of each system,and realizes the high precision timing and trigger.At the same time,the system has certain flexibility and expansibility,which lays the foundation for the complete and orderly conduct of NNBI experiment.Figure [38] table [7] reference [86]...