WO2016197364A1 - 实时计算相移信号方法及系统、等离子体诊断方法及系统 - Google Patents

实时计算相移信号方法及系统、等离子体诊断方法及系统 Download PDF

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WO2016197364A1
WO2016197364A1 PCT/CN2015/081243 CN2015081243W WO2016197364A1 WO 2016197364 A1 WO2016197364 A1 WO 2016197364A1 CN 2015081243 W CN2015081243 W CN 2015081243W WO 2016197364 A1 WO2016197364 A1 WO 2016197364A1
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signal
track
measurement
module
time period
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PCT/CN2015/081243
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French (fr)
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周艳
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核工业西南物理研究院
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Priority to EP15894634.3A priority Critical patent/EP3297408A4/en
Priority to PCT/CN2015/081243 priority patent/WO2016197364A1/zh
Priority to CN201580028806.4A priority patent/CN106461710B/zh
Publication of WO2016197364A1 publication Critical patent/WO2016197364A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D13/00—Circuits for comparing the phase or frequency of two mutually-independent oscillations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma

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  • the invention relates to the field of nuclear fusion plasma diagnosis, in particular to a method and a system for real-time calculation of phase shift signals capable of real-time calculation of dynamic phase shift of multi-IF signals applicable to polarized light measurement technology, and to the application of the above-mentioned real-time Method and system for calculating phase shift signal plasma diagnostic method and system.
  • plasma electron density and current density are the most basic and most critical physical parameters for studying plasma behavior and physics.
  • International and domestic research institutions are continually investing in human and material resources to research and develop more reliable, real-time, high-space-resolution diagnostic techniques and methods to meet the emerging research needs of new physical phenomena.
  • the plasma electron density and current density distribution are measured by a laser polarization interferometer.
  • the working principle is laser interference technology: the beam from the same laser source is split into two beams by a beam splitter, and one beam passes through the measured medium. (called the measurement beam), a beam of medium that is not measured (called the reference beam), the refractive index of the measured medium is obtained by comparing the phase changes of the measurement beam and the reference beam, and the formula of the dispersion relation is used to obtain the electron density. And current density. Since the laser detector currently used has a low detection rate for high-frequency lasers, the high-frequency optical signal is usually converted into a low-frequency modulation signal by a laser frequency modulation technique, and the low-frequency signal is also referred to as an intermediate frequency signal.
  • the intermediate frequency signal of a laser interferometer used for plasma density measurement was generated by rotating a cylindrical grating to generate a Doppler shift of the laser beam irradiated thereon.
  • the frequency of the intermediate frequency signal generated due to uniform grating rotation speed Fixed, such as 10 kHz, electronic amplification and filtering are fixed at the center frequency of 10 kHz, the filtering bandwidth can be 10 kHz ⁇ 2 kHz, subsequent signal amplification and phase difference calculations are easy to process and calculate with the inherent electronic circuitry, due to fixed frequency, phase
  • the comparison uses the phase comparison of the reference track and the measuring track at the same time point to obtain the phase difference. In this way, the mechanical speed of the grating should not be improved, otherwise the dynamic balance imbalance is easy to occur, so the time resolution of the measuring system can only be 100 micro. In seconds, it is impossible to meet the needs of physical research.
  • the international mainstream polarization interferometer uses the laser difference frequency technology to generate the required intermediate frequency signal (the two output signals with slightly different wavelengths are subtracted to obtain an intermediate frequency signal). That is, three or two lasers are used to generate three or one intermediate frequency signals, and the intermediate frequency signals are divided into measuring channels and reference tracks by a beam splitter. The parameters of density and current are obtained by comparing the phase of the intermediate frequency signal passing through the plasma with the phase of the intermediate frequency signal without passing through the plasma.
  • laser beat frequency technology can obtain higher frequency IF signals, the time resolution of system measurement is improved.
  • the output frequency of a single laser will drift with time, which will cause the frequency of the intermediate frequency signal to move.
  • phase comparison calculation of similar measurement systems at home and abroad can not realize online real-time calculation. It can only be processed offline or rely on personnel to adjust the laser parameters dynamically to meet the working range of the phase difference meter.
  • the technical problem solved by the present invention is that in the prior art, due to the frequency drift of the laser, it is difficult to realize the real-time calculation of the phase difference in the nuclear fusion test process, thereby providing a real-time calculation dynamic that can be applied in the case where the laser frequency is drifted.
  • the method of phase shifting signals also provides a system for calculating a dynamic phase shift signal in real time and a plasma diagnostic method and system using the above method and system for calculating a phase shift signal in real time.
  • a method of calculating a dynamic phase shift signal in real time comprising the following steps:
  • Steps S02 to S04 are repeated to calculate a phase difference between the measurement channel and the reference channel intermediate frequency signal in the next period.
  • step of filtering is further included between step S03 and step S04:
  • the measurement channel of the current time period obtained in step S03 and the frequency domain of the reference track are respectively within the set bandwidth range.
  • the signal is bandpass filtered, the signal outside the bandwidth is set to zero, and the phase difference is calculated using the filtered frequency domain signal in step S04.
  • the step S03, the step S04 and/or the filtering step are implemented by using FPGA technology.
  • the corresponding reference track also includes three intermediate frequency signals, and the phase difference of the three pairs of intermediate frequency signals in each time period is calculated by using steps S01 to S05 respectively.
  • the invention also provides a nuclear fusion plasma diagnosis method, which uses the real-time calculation method of dynamic phase shift signal to calculate the phase difference in real time, and sets the following steps after step S04:
  • the electron density and current density of the current time period are calculated based on the obtained phase difference, and the calculated result is saved, displayed, and/or fed back.
  • the invention further provides a system for calculating a dynamic phase shift signal in real time, comprising:
  • a measurement channel A/D conversion module for reading an intermediate frequency signal of a current time measurement track and performing A/D conversion into a digital signal
  • a reference track A/D conversion module for reading an intermediate frequency signal of a current time reference track and performing A/D conversion into a digital signal
  • a measurement path fast Fourier transform module configured to perform fast Fourier transform on the digital signal from the measurement channel A/D conversion module to obtain a frequency domain signal, and find an accurate frequency of the intermediate frequency signal of the measurement track in a current time period
  • a reference fast Fourier transform module configured to perform fast Fourier transform on the digital signal from the reference track A/D conversion module to obtain a frequency domain signal, and find an accurate frequency of the intermediate frequency signal of the reference track in the current time period
  • the phase comparison module is configured to perform conjugate calculation on the reference channel of the current time period and the frequency domain signal of the measurement track according to the accurate frequency of the intermediate frequency signal of the current time measurement track and the reference track, and obtain the intermediate frequency signal of the measurement track and the reference track at the current The phase difference of the time period.
  • the system for calculating a dynamic phase shift signal in real time further comprises a measurement channel filtering module and/or a parameter Pathway filter module:
  • the measuring channel filtering module uses the measuring track fast Fourier transform module to find the accurate frequency of the intermediate frequency signal of the measuring track in the current time period as the center frequency, and obtains the fast Fourier transform module of the measuring track within the set bandwidth range.
  • the frequency domain signal of the current time measurement channel is band-pass filtered, the signal outside the bandwidth is set to zero, and the phase difference difference is calculated by using the filtered frequency domain signal in the phase comparison module;
  • the reference channel filtering module uses the reference track fast Fourier transform module to find the accurate frequency of the intermediate frequency signal of the reference track in the current time period as the center frequency, and obtains the reference channel fast Fourier transform module within the set bandwidth range.
  • the frequency domain signal of the reference channel of the current time period is band-pass filtered, and the signal outside the bandwidth is set to zero, and the phase difference difference is calculated by using the filtered frequency domain signal in the phase comparison module.
  • the measurement track fast Fourier transform module, the reference track fast Fourier transform module, the measurement channel filtering module, the reference channel filtering module and/or the phase comparison module are burned on an FPGA chip.
  • the present invention also provides a nuclear fusion plasma diagnostic system including the system for calculating a dynamic phase shift signal in real time, the nuclear fusion plasma diagnostic system further comprising an electron density/current density calculation module, the electron density/current density calculation The module calculates the electron density and current density of the plasma in real time according to the phase difference calculated by the system in real time for calculating the dynamic phase shift signal.
  • the electron density/current density calculation module is programmed on an FPGA chip.
  • the nuclear fusion plasma diagnostic system further includes a storage module for storing the calculation result, a display module for displaying the calculation result, and/or a feedback system for feeding back the calculation result.
  • a storage module for storing the calculation result
  • a display module for displaying the calculation result
  • a feedback system for feeding back the calculation result.
  • the method and system for real-time computing dynamic phase shift signal of the invention utilizes a new dynamic medium frequency identification method using FPGA technology to realize unreliable and reliable real-time phase calculation and output, and the above-mentioned real-time calculation phase shift signal method and system
  • the plasma diagnostic method and system can further reliably realize unattended real-time electron density and current density measurement, specifically:
  • the frequency of the intermediate frequency signal is dynamically determined in the time period allowed by the measured time resolution, and the measurement failure of the phase difference meter of the solidified intermediate frequency due to the intermediate frequency drift is avoided;
  • the filtering and phase difference calculation of the signal is set after determining the frequency of the intermediate frequency signal, which can be greatly improved.
  • the long-term measurement is divided into small time periods, which can ensure the real-time output of the signal and provide data for the Tokamak density and current density feedback control.
  • FIG. 1 is a block diagram showing the system configuration of a real-time dynamic phase shift signal according to the present invention.
  • 1 measuring channel A/D conversion module 1 measuring channel A/D conversion module, 2 measuring channel filtering module, 3 measuring track fast Fourier transform module, 4 reference track A/D conversion module, 5 reference channel filtering module, 6 reference track fast Fourier transform module, 7 phase comparison module .
  • the method for calculating a dynamic phase shift signal in real time comprises the following steps:
  • Steps S02 to S04 are repeated to calculate a phase difference between the measurement channel and the reference channel intermediate frequency signal in the next period.
  • the system for calculating a dynamic phase shift signal in real time includes:
  • the measuring track A/D conversion module 1 is configured to read the intermediate frequency signal of the current time measuring track and perform A/D conversion into a digital signal;
  • the reference track A/D conversion module 4 is configured to read the intermediate frequency signal of the current time reference track and perform A/D conversion into a digital signal;
  • a fast Fourier transform module 3 for measuring a digital signal from the measurement channel A/D conversion module, performing fast Fourier transform to obtain a frequency domain signal, and finding an accurate frequency of the intermediate frequency signal of the measurement track in a current time period;
  • a reference fast Fourier transform module 6 for performing fast Fourier transform on the digital signal from the reference track A/D conversion module to obtain a frequency domain signal, and finding an accurate frequency of the intermediate frequency signal of the reference track in the current time period;
  • the phase comparison module 7 is configured to perform conjugate calculation on the reference channel of the current time period and the frequency domain signal of the measurement track according to the accurate frequency of the intermediate frequency signal of the current time measurement track and the reference track, and obtain the intermediate frequency signal of the measurement track and the reference track. The phase difference of the current time period.
  • the above method for calculating a dynamic phase shift signal in real time actually divides the intermediate frequency signals of the measurement track and the reference track into reasonable small segments according to time.
  • This so-called reasonable segment means that the time segment can satisfy the measurement.
  • the time resolution needs, and the data can also be used to achieve Fourier transform within the accuracy range, such as the frequency of the intermediate frequency signal is 1MHz, the sampling rate is 12.5MHz, and the time period is 20.48 microseconds.
  • the segmentation process is known to those skilled in the art. This can be done in accordance with known techniques in connection with the present invention.
  • Each small segment of the signal is recorded into the electronic chip by A/D conversion, and the exact frequency of the intermediate frequency signal is found by Fourier transform, and can be filtered within the specified bandwidth according to the found intermediate frequency signal value to reduce noise;
  • the phase comparison between the reference track signal and the track signal is performed, and the phase difference of the intermediate frequency signal of the measurement track and the reference track in the current time period is obtained, thereby obtaining data of density and current density and outputting.
  • the method of calculating the dynamic phase shift signal in real time of the present invention may set the filtering step between step S03 and step S04:
  • step S03 Taking the accurate frequency of the intermediate frequency signal of the measurement track and the reference track found in step S03 in the current time period as the center frequency, and performing the frequency domain signal of the current time measurement track and the reference track obtained in step S03 within the set bandwidth range.
  • Bandpass filtering sets the signal outside the bandwidth to zero, and uses the filtered frequency domain signal to complete the phase difference calculation in step S04.
  • the measurement channel can also be set in the system for calculating the dynamic phase shift signal in real time provided by the present invention.
  • the measuring channel filtering module uses the measuring track fast Fourier transform module to find the accurate frequency of the IF signal of the measuring track in the current time period as the center frequency, and the frequency of the current time measuring track obtained by the measuring track fast Fourier transform module within the set bandwidth range
  • the domain signal is band-pass filtered, and the signal outside the bandwidth is set to zero, and the phase difference is calculated by using the filtered frequency domain signal in the phase comparison module;
  • the reference channel filtering module uses the reference track fast Fourier transform module to find the accurate frequency of the intermediate frequency signal of the reference track in the current time period as the center frequency, and the frequency of the current time reference channel obtained by the reference track fast Fourier transform module in the set bandwidth range.
  • the domain signal is bandpass filtered to set the signal outside the bandwidth to zero, and the phase difference module uses the filtered frequency domain signal to complete the phase difference calculation.
  • the above method for calculating a dynamic phase shift signal in real time selects a frequency domain signal for phase difference calculation (for a calculation method, refer to the article Rev. Sci. Instrum. Vol. 68 No. 1, p902 (1997)), because the calculation amount is more conventional.
  • the calculation method is small, which can greatly improve the calculation efficiency.
  • the FPGA can realize fast real-time calculation.
  • the steps of step S03, step S04 and/or filtering are implemented by FPGA technology, so that the real-time performance of the system can be greatly improved. Meet the requirements of existing nuclear fusion tests.
  • the measurement track fast Fourier transform module, the reference track fast Fourier transform module, the measurement channel filtering module, the reference channel filtering module and/or the phase comparison module are burned on the FPGA chip. on.
  • the measurement track includes three intermediate frequency signals, and the corresponding reference channel also includes three intermediate frequency signals.
  • the phase difference of the three pairs of intermediate frequency signals in each period is calculated by using steps S01 to S05, respectively.
  • the nuclear fusion plasma diagnosis method based on the above method for calculating a dynamic phase shift signal in real time calculates the phase difference by using the above method for calculating a dynamic phase shift signal in real time, and sets the following steps after step S04:
  • the electron density and current density were calculated from the obtained phase difference.
  • the steps of saving, presenting, and/or feeding back the calculated results can be further set as needed.
  • the nuclear fusion plasma diagnostic system includes an electron density/current density calculation module in addition to the above-mentioned system for real-time calculation of dynamic phase shift signals, and the electronic density/current density calculation module calculates dynamic phase shift according to real-time calculation.
  • the phase difference of the real-time calculation of the signal system calculates the electron density and current density of the plasma in real time, and can further set the storage for storing the calculation result as needed.
  • the measurement channel and the reference channel signal respectively convert the analog signal into a signal signal adjustment process such as a numerical signal, an intermediate frequency confirmation, and a signal bandpass amplification.
  • the measurement and reference signals from the detector are respectively analog signals containing one or three intermediate frequencies, usually with a signal amplitude of 1-4 volts and a signal frequency in the range of 600 kHz to 3 MHz.
  • Two A/D conversion modules convert the analog signal from the detector into a digital signal.
  • Two fast Fourier transform units convert the digitized time domain signal into a frequency domain signal, and determine a specific frequency value of the intermediate frequency signal; if there are three intermediate frequencies in the signal, respectively determine the positions of the three intermediate frequencies, if only one intermediate frequency is found A frequency value.
  • the filtering module dynamically centers the found intermediate frequency value to determine a certain bandwidth (such as a 1 MHz intermediate frequency signal, taking a filtering window of 195 kHz), and sets a frequency domain signal outside the bandwidth to zero; there are three intermediate frequency pairs respectively.
  • a certain bandwidth such as a 1 MHz intermediate frequency signal, taking a filtering window of 195 kHz
  • the filtered measurement and reference signals are sent to the phase comparison module 7, and the phase difference is obtained through the conjugate calculation of the reference and measurement signals, and the electron density and current density of the plasma can be calculated according to the phase difference (the phase difference is proportional to the electrons) Density and current density) can then be stored in a computer, while phase difference signals, electron density, current density, etc. are output to a display or other hardware control system, such as a density feedback system, for a period of time. The above process is repeated for the next time period until the end of the discharge.
  • a certain bandwidth such as a 1 MHz intermediate frequency signal, taking a filtering window
  • a polarization interferometer built with three HCOOH lasers with a laser wavelength of 432 microns.
  • the beams of the three lasers are split into measurement and reference beams, and are combined into a beam of light before the measurement detector and the reference detector. .
  • the combined beam contains three intermediate frequency signals that are differentially frequencyd by three different lasers, with frequencies of 700 kHz, 1.2 MHz, and 1.9 MHz, respectively.
  • Set the sampling rate to 12.5MHz.
  • the measurement channel and the reference channel signal are respectively subjected to fast Fourier transform to find three intermediate frequencies with center frequencies of 700 kHz, 1.2 MHz, and 1.9 MHz, respectively, and the filter window is 195 kHz, respectively, for three intermediate frequencies, with the peak as the center, to filter the window. Bandpass filtering for bandwidth.
  • the measurement and reference track signals then enter the phase comparison module 7, and for each intermediate frequency, the corresponding measurement and the reference phase comparison are performed, and the phase difference is obtained by the conjugate calculation of the signals of the reference track and the measurement track. Then, according to the formula of the dispersion relation, the electron density and The value of the current density is output at the input of the display and density feedback controller. Since the entire signal processing flow uses FPGA technology, the time taken to complete a cycle is 180 microseconds. After that, the above process is repeated by taking the data of the next time period until the end of the discharge.

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Abstract

一种实时计算动态相移信号的方法及系统，该方法包括以下步骤：分别将测量道和参考道的中频信号进行分段；分别读取当前时段测量道和参考道中的中频信号并进行A/D转换成数字信号；将得到的当前时段的测量道和参考道的数字信号分别进行傅立叶变换转变为频域信号，同时得到当前时段内的准确频率；根据当前时段准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算获得相位差。该实时计算动态相移信号的方法及系统能够实现无人值守的可靠的实时相位计算和输出，利用上述实时计算相移信号的方法及系统的等离子体诊断方法及系统可以进一步可靠地实现无人值守的实时电子密度和电流密度的测量。

Description

实时计算相移信号方法及系统、等离子体诊断方法及系统 技术领域
本发明涉及核聚变等离子体诊断领域，尤其涉及一种能够应用于偏振光测量技术的多中频信号的动态相移的实时计算的实时计算相移信号的方法及系统，本发明还涉及应用上述实时计算相移信号的方法及系统的等离子体诊断方法及系统。
背景技术
在核聚变装置和物理研究中，等离子体电子密度和电流密度是研究等离子体行为和物理的最为基础、也最为关键的物理参数。国际和国内的相关研究机构正在不断地投入人力和物力，研究和发展更可靠的、可实时处理的高时空分辨的诊断技术和方法，以满足不断出现的新的物理现象的研究需求。
通常等离子体电子密度和电流密度分布测量采用的是激光偏振干涉仪，其工作原理利用的是激光干涉技术：即来自同一激光源的光束通过分束器被分成两束，一束通过测量的介质(称为测量束)，一束不经过被测量的介质(称为参考束)，通过比较测量束和参考束的相位变化得到所测量介质的折射率，利用色散关系的公式，从而得到电子密度和电流密度。由于目前使用的激光探测器对于高频激光探测率低，通常通过激光调频技术将高频的光信号变成低频的调制信号，这种低频的信号也称为中频信号。
以往，用于等离子体密度测量的激光干涉仪的中频信号是通过转动的柱面光栅将照射其上的激光光束产生多谱勒频移来产生的，由于光栅转速均匀，所产生的中频信号频率固定，比如10kHz，电子学的放大和滤波都固定在中心频率10kHz，滤波带宽可以为10kHz±2kHz，后续的信号放大和相位差计算易于用固有的电子学线路处理和计算，由于频率固定，相位比较采用的是参考道与测量道相同时间点的相位比较，得到相位差值，这种方法，光栅机械转速不宜提高，否则容易出现动平衡失调，从而测量系统的时间分辨率只能在100微秒左右，无法满足物理研究的需要。
目前，国际主流的偏振干涉仪采用的是激光差频技术产生所需要的中频信号(两台波长稍有差别的激光器输出信号相减就得到一个中频信号)。即用三台或两台激光器差频产生三个或一个中频信号，这些中频信号经过分束器分成测量道和参考道。用通过等离子体的中频信号与没有经过等离子体的中频信号的相位比较来获得密度和电流的参数。虽然激光差频技术能够获得较高频率的中频信号，从而提高系统测量的时间分辨率。但是，由于系统所用的激光器受环境温度变化影响，单个激光的输出频率会随着时间的变化产生漂移，进而造成中频信号频率移动，而用传统的相位差计就很难确认信号中频频率，甚至无法正常计算相位大小。目前国内外同类测量系统的相位比较计算还不能实现在线实时计算，只能是离线处理或者依靠人员值守，动态调整激光参数，以满足相位差计的工作范围。
发明内容
本发明解决的技术问题是现有技术中由于激光器的频率漂移导致在核聚变试验过程中难以实现实时计算相位差的问题，进而提供一种能够在激光器频率产生漂移的情况下应用的实时计算动态相移信号的方法，本发明还提供实时计算动态相移信号的系统以及应用上述实时计算相移信号方法及系统的等离子体诊断方法及系统。
为了解决上述技术问题，本发明采用的技术方案如下：
实时计算动态相移信号的方法，包括以下步骤：
S01：分别将测量道和参考道的中频信号进行分段；
S02：分别读取当前时段测量道和参考道中的中频信号并进行A/D转换成数字信号；
S03：将得到的当前时段的测量道和参考道的数字信号分别进行傅立叶变换转变为频域信号，同时分别找到测量道和参考道的中频信号在当前时段内的准确频率；
S04：根据当前时段测量道和参考道的中频信号的准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算，获得测量道与参考道的中频信号在当前时段的相位差；
S05：重复步骤S02至S04，计算测量道与参考道的中频信号在下一时段内的相位差。
优选地，在步骤S03和步骤S04之间还包括滤波的步骤：
以步骤S03中找到的测量道、参考道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内分别对步骤S03中得到的当前时段的测量道、参考道的频域信号进行带通滤波，将带宽之外的信号置为零，并在步骤S04中采用滤波后的频域信号完成相位差的计算。
优选地，步骤S03、步骤S04和/或所述滤波的步骤采用FPGA技术实现。
优选地，当测量道包括三个中频信号，相应的参考道也包括三个中频信号，分别同时采用步骤S01至步骤S05计算三对中频信号在各时段的相位差。
本发明还提供核聚变等离子体诊断方法，采用所述实时计算动态相移信号的方法实时计算相位差，并在步骤S04之后设置如下步骤：
根据得到的相位差计算当前时段的电子密度和电流密度，并把计算的结果进行保存、展示和/或反馈。
本发明进一步提供实时计算动态相移信号的系统，包括：
测量道A/D转换模块，用于读取当前时段测量道的中频信号并进行A/D转换成数字信号；
参考道A/D转换模块，用于读取当前时段参考道的中频信号并进行A/D转换成数字信号；
测量道快速傅立叶变换模块，用于将来自所述测量道A/D转换模块的数字信号，进行快速傅立叶变换得到频域信号，并找到测量道的中频信号的在当前时段内的准确频率；
参考道快速傅立叶变换模块，用于将来自所述参考道A/D转换模块的数字信号，进行快速傅立叶变换得到频域信号，并找到参考道的中频信号在当前时段内的准确频率；
相位比较模块，用于根据当前时段测量道和参考道的中频信号的准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算，获得测量道与参考道的中频信号在当前时段的相位差。
优选地，所述实时计算动态相移信号的系统还包括测量道滤波模块和/或参 考道滤波模块：
所述测量道滤波模块以所述测量道快速傅立叶变换模块找到测量道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对所述测量道快速傅立叶变换模块得到的当前时段测量道的频域信号进行带通滤波，将带宽之外的信号置为零，并在所述相位比较模块中采用滤波后的频域信号完成相位差的计算；
所述参考道滤波模块以所述参考道快速傅立叶变换模块找到参考道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对所述参考道快速傅立叶变换模块得到的当前时段参考道的频域信号进行带通滤波，将带宽之外的信号置为零，并在所述相位比较模块中采用滤波后的频域信号完成相位差的计算。
优选地，所述测量道快速傅立叶变换模块、所述参考道快速傅立叶变换模块、所述测量道滤波模块、所述参考道滤波模块和/或所述相位比较模块烧录在FPGA芯片上。
本发明最后还提供包括所述实时计算动态相移信号的系统的核聚变等离子体诊断系统，所述核聚变等离子体诊断系统还包括电子密度/电流密度计算模块，所述电子密度/电流密度计算模块根据所述实时计算动态相移信号的系统实时计算的相位差实时计算等离子体的电子密度和电流密度。
优选的所述电子密度/电流密度计算模块烧录在FPGA芯片上。
优选地，所述核聚变等离子体诊断系统还包括用于存储计算结果的存储模块、用于显示计算结果的显示模块和/或用于将计算结果进行反馈的反馈系统。本发明的有益效果如下：
本发明的实时计算动态相移信号的方法及系统利用FPGA技术采用一种新的动态的中频识别方法，实现无人值守的可靠的实时相位计算和输出，利用上述实时计算相移信号方法及系统的等离子体诊断方法及系统可以进一步可靠地实现无人值守的实时电子密度和电流密度的测量，具体的：
在测量的时间分辨率所允许的时间段中动态判定中频信号频率，避免了固化中频的相位差计因为中频漂移造成的测量失败；
信号的滤波和相位差计算被设置在判定中频信号频率之后，可以大大提高 相位计算的精度；
同时将长时间的测量划分为小的时间段，可以保证信号的实时输出，为托卡马克密度和电流密度反馈控制提供数据。
附图说明
图1为本发明的实时计算动态相移信号的系统构成方框图。
图中：
1测量道A/D转换模块、2测量道滤波模块、3测量道快速傅立叶变换模块、4参考道A/D转换模块、5参考道滤波模块、6参考道快速傅立叶变换模块、7相位比较模块。
具体实施方式
下面结合附图和具体实施例对本发明的技术方案和有益效果进一步进行说明。
本发明的实时计算动态相移信号的方法，包括以下步骤：
S01：分别将测量道和参考道的中频信号进行分段；
S02：分别读取当前时段测量道和参考道中的中频信号并进行A/D转换成数字信号；
S03：将得到的当前时段的测量道和参考道的数字信号分别进行傅立叶变换转变为频域信号，同时分别找到测量道和参考道的中频信号在当前时段内的准确频率；
S04：根据当前时段测量道和参考道的中频信号的准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算，获得测量道与参考道的中频信号在当前时段的相位差；
S05：重复步骤S02至S04，计算测量道与参考道的中频信号在下一时段内的相位差。
相应的，参见附图1，本发明提供的实时计算动态相移信号的系统，包括：
测量道A/D转换模块1，用于读取当前时段测量道的中频信号并进行A/D转换成数字信号；
参考道A/D转换模块4，用于读取当前时段参考道的中频信号并进行A/D转换成数字信号；
测量道快速傅立叶变换模块3，用于将来自，测量道A/D转换模块的数字信号，进行快速傅立叶变换得到频域信号，并找到测量道的中频信号的在当前时段内的准确频率；
参考道快速傅立叶变换模块6，用于将来自，参考道A/D转换模块的数字信号，进行快速傅立叶变换得到频域信号，并找到参考道的中频信号在当前时段内的准确频率；
相位比较模块7，用于根据当前时段测量道和参考道的中频信号的准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算，获得测量道与参考道的中频信号在当前时段的相位差。
简单来说，本发明的上述实时计算动态相移信号的方法实际上是将测量道和参考道的中频信号按时间分成合理的小段，这个所谓合理就的小段是指这个时间段可以满足测量的时间分辨率的需要，同时还可以用这段数据实现精度范围内的傅立叶变换，比如中频信号频率为1MHz，采样率为12.5MHz，取时间段为20.48微秒，分段过程本领域的技术人员可以结合本发明根据公知技术完成。每个小段的信号通过A/D变换记入电子学芯片，通过傅立叶变换，找到中频信号的准确频率，并可以根据找到的中频信号值，在规定的带宽内滤波，减少噪声；并在滤波后进行参考道信号与测量道信号的相位比较，得到测量道和参考道的中频信号在当前时段的相位差，进而得到密度和电流密度的数据并输出。接着按同样方式计算下一个时间段的相位。将每个时间段的数据连接起来就得到整个时间的密度和电流密度的数据。
如上所述，为了较少噪声，以提高相位计算的精度，本发明的实时计算动态相移信号的方法可以在步骤S03和步骤S04之间设置滤波的步骤：
以步骤S03中找到的测量道和参考道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对步骤S03中得到的当前时段测量道和参考道的频域信号进行带通滤波，将带宽之外的信号置为零，并在步骤S04中采用滤波后的频域信号完成相位差的计算。
相应的，本发明提供的实时计算动态相移信号的系统中也可以设置测量道 滤波模块2和/或参考道滤波模块5：
测量道滤波模块以测量道快速傅立叶变换模块找到测量道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对测量道快速傅立叶变换模块得到的当前时段测量道的频域信号进行带通滤波，将带宽之外的信号置为零，并在相位比较模块中采用滤波后的频域信号完成相位差的计算；
参考道滤波模块以参考道快速傅立叶变换模块找到参考道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对参考道快速傅立叶变换模块得到的当前时段参考道的频域信号进行带通滤波，将带宽之外的信号置为零，并在，相位比较模块中采用滤波后的频域信号完成相位差的计算。
本发明的上述实时计算动态相移信号的方法选择频域信号进行相位差的计算(计算方法可以参考文章Rev.Sci.Instrum.Vol.68No.1,p902(1997))，由于计算量较传统计算方法较小，可以大幅度提高计算效率，同时，FPGA可是实现快速实时计算，将步骤S03、步骤S04和/或滤波的步骤采用FPGA技术实现，使系统计算的实时性大幅度提高，完全可以满足现有的核聚变试验的要求。对应的，本发明的实时计算动态相移信号的系统中，测量道快速傅立叶变换模块、参考道快速傅立叶变换模块、测量道滤波模块、参考道滤波模块和/或相位比较模块烧录在FPGA芯片上。
有些系统中，测量道包括三个中频信号，相应的参考道也包括三个中频信号，此时分别需要同时采用步骤S01至步骤S05计算三对中频信号在各时段的相位差。
本发明提供的基于上述实时计算动态相移信号的方法的核聚变等离子体诊断方法，采用上述实时计算动态相移信号的方法计算相位差，并在步骤S04之后设置如下步骤：
根据得到的相位差计算电子密度和电流密度。
并可以根据需要进一步设置将计算的结果进行保存、展示和/或反馈的步骤。
相应的，本发明提供的核聚变等离子体诊断系统，除包括上述实时计算动态相移信号的系统外，还包括电子密度/电流密度计算模块，电子密度/电流密度计算模块根据实时计算动态相移信号的系统实时计算的相位差实时计算等离子体的电子密度和电流密度，并可进一步根据需要设置用于存储计算结果的存储 模块、用于显示计算结果的显示模块和/或用于将计算结果进行反馈的反馈系统。
应用本发明的实时计算动态相移信号的系统的核聚变等离子体诊断系统的工作过程如下：
在进行相位比较之前，测量道和参考道信号分别进行模拟信号转化为数值信号、中频确认、信号带通放大等信号调整过程。来自探测器的测量与参考信号分别为包含一个或三个中频的模拟信号，通常信号幅值为1—4伏，信号频率在600kHz—3MHz范围内。两个A/D转换模块将来自探测器的模拟信号转换为数字信号。两个快速傅立叶变换单元将数字化的时域信号变成频域信号，同时确定出中频信号的具体频率值；如果信号中有三个中频则分别确定出三个中频的位置，如果只有一个中频则找到一个频率值。滤波模块动态地将已找到的中频值为中心，确定一定的带宽(如1MHz的中频信号，取滤波窗口为195kHz)，将带宽之外的频域信号置为零；有三个中频的分别对每个中频滤波。经过滤波的测量和参考信号送入相位比较模块7，经过参考和测量信号的共轭计算，得到相位差，并可根据该相位差计算等离子体的电子密度和电流密度(该相位差比例于电子密度和电流密度)，然后可以存储在计算机中，同时相位差信号、电子密度、电流密度等输出到显示器或其它硬件控制系统，如密度反馈系统，完成一个时间周期的运行。在下一个时间周期重复运行上述过程，直至放电结束。
下面结合一个实例对本发明的技术方案进一步进行说明：
一套用三台HCOOH激光器搭建的偏振干涉仪，其激光波长为432微米，三台激光器的光束分成测量道和参考道光束，并在测量道探测器和参考道探测器前分别合束成一束光。合束光中包含三个由三台不同的激光器差频出的中频信号，频率分别为700kHz，1.2MHz，1.9MHz。设置采样率为12.5MHz，在放电的开始时刻，从测量道探测器和参考道探测器的信号流中分别取256个点的数据送入相位比较器，经过A/D变换，将测量道和参考道信号转换成数字信号。测量道和参考道信号分别通过快速傅立叶变换，找出中心频率分别为700kHz，1.2MHz，1.9MHz的三个中频，取滤波窗口为195kHz，分别对三个中频，以峰值为中心，以滤波窗口为带宽进行带通滤波。之后测量道和参考道信号进入相位比较模块7，对于每个中频进行相应的测量和参考的相位比较，通过参考道和测量道的信号的共扼计算得到相位差值。然后可以根据色散关系的公式，得到电子密度和 电流密度的值，并输出在显示器和密度反馈控制器输入端，由于整个信号处理流程应用FPGA技术，完成一个循环所用时间为180微秒。之后，再取下一个时间段的数据重复上述过程，直至放电结束。
本领域的普通技术人员将会意识到，这里所述的实施例是为了帮助读者理解本发明的原理，应被理解为本发明的保护范围并不局限于这样的特别陈述和实施例。本领域的普通技术人员科研根据本发明公开的这些技术启示做出各种不脱离本发明实质的其它各种具体变形和组合，这些变形和组合仍然在本发明的保护范围内。

Claims (10)

  1. 实时计算动态相移信号的方法，其特征在于：包括以下步骤：
    S01：分别将测量道和参考道的中频信号进行分段；
    S02：分别读取当前时段测量道和参考道中的中频信号并进行A/D转换成数字信号；
    S03：将得到的当前时段的测量道和参考道的数字信号分别进行傅立叶变换转变为频域信号，同时分别找到测量道和参考道的中频信号在当前时段内的准确频率；
    S04：根据当前时段测量道和参考道的中频信号的准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算，获得测量道与参考道的中频信号在当前时段的相位差；
    S05：重复步骤S02至S04，计算测量道与参考道的中频信号在下一时段内的相位差。
  2. 如权利要求1所述实时计算动态相移信号的方法，其特征在于：在步骤S03和步骤S04之间还包括滤波的步骤：
    以步骤S03中找到的测量道、参考道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内分别对步骤S03中得到的当前时段的测量道、参考道的频域信号进行带通滤波，将带宽之外的信号置为零，并在步骤S04中采用滤波后的频域信号完成相位差的计算。
  3. 如权利要求2所述实时计算动态相移信号的方法，其特征在于：步骤S03、步骤S04和/或所述滤波的步骤采用FPGA技术实现。
  4. 如权利要求1至3中任一项所述实时计算动态相移信号的方法，其特征在于：当测量道包括三个中频信号，相应的参考道也包括三个中频信号，分别同时采用步骤S01至步骤S05计算三对中频信号在各时段的相位差。
  5. 核聚变等离子体诊断方法，其特征在于：采用如权利要求1至4中任一项所述实时计算动态相移信号的方法实时计算相位差，并在步骤S04之后设置如下步骤：
    根据得到的相位差计算当前时段的电子密度和电流密度，并把计算的结果进行保存、展示和/或反馈。
  6. 实时计算动态相移信号的系统，其特征在于，包括：
    测量道A/D转换模块，用于读取当前时段测量道的中频信号并进行A/D转换成数字信号；
    参考道A/D转换模块，用于读取当前时段参考道的中频信号并进行A/D转换成数字信号；
    测量道快速傅立叶变换模块，用于将来自所述测量道A/D转换模块的数字信号，进行快速傅立叶变换得到频域信号，并找到测量道的中频信号的在当前时段内的准确频率；
    参考道快速傅立叶变换模块，用于将来自所述参考道A/D转换模块的数字信号，进行快速傅立叶变换得到频域信号，并找到参考道的中频信号在当前时段内的准确频率；
    相位比较模块，用于根据当前时段测量道和参考道的中频信号的准确频率，对当前时段的参考道和测量道的频域信号进行共轭计算，获得测量道与参考道的中频信号在当前时段的相位差。
  7. 如权利要求6所述实时计算动态相移信号的系统，其特征在于，所述系统还包括测量道滤波模块和/或参考道滤波模块：
    所述测量道滤波模块以所述测量道快速傅立叶变换模块找到测量道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对所述测量道快速傅立叶变换模块得到的当前时段测量道的频域信号进行带通滤波，将带宽之外的信号置为零，并在所述相位比较模块中采用滤波后的频域信号完成相位差的计算；
    所述参考道滤波模块以所述参考道快速傅立叶变换模块找到参考道的中频信号在当前时段内的准确频率为中心频率，在设定的带宽范围内对所述参考道快速傅立叶变换模块得到的当前时段参考道的频域信号进行带通滤波，将带宽之外的信号置为零，并在所述相位比较模块中采用滤波后的频域信号完成相位差的计算。
  8. 如权利要求7所述实时计算动态相移信号的系统，其特征在于，所述测量道快速傅立叶变换模块、所述参考道快速傅立叶变换模块、所述测量道滤波模块、所述参考道滤波模块和/或所述相位比较模块烧录在FPGA芯片上。
  9. 包括权利要求6至8中任一项所述实时计算动态相移信号的系统的核聚变 等离子体诊断系统，其特征在于：所述核聚变等离子体诊断系统还包括电子密度/电流密度计算模块，所述电子密度/电流密度计算模块根据所述实时计算动态相移信号的系统实时计算的相位差实时计算等离子体的电子密度和电流密度。
  10. 如权利要求9所述核聚变等离子体诊断系统，其特征在于：所述电子密度/电流密度计算模块烧录在FPGA芯片上，所述核聚变等离子体诊断系统还包括用于存储计算结果的存储模块、用于显示计算结果的显示模块和/或用于将计算结果进行反馈的反馈系统。
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