P. V. Zubarev

Precision Phase Discriminator for the Heterodyne Interferometric Plasma-Density Measurement Technique

The discriminator is intended for the plasma density recording systems based on optical heterodyne interferometry. The discriminator has a high phase resolution (10–3 rad) and a virtually unlimited dynamic range in a modulation band of up to one-half of the carrier frequency (1 MHz). These features allow one to use the discriminator for recording phase shifts caused by both slow and fast plasma-density fluctuations on setups with high levels of thermal and mechanical influences on the interferometer.

Prototype of fast data acquisition systems for ITER divertor Thomson scattering diagnostic

Thomson scattering diagnostic is the most reliable and widely used method to measure electron temperature and density profiles of magnetically confined plasma. The prototype of data acquisition system for ITER divertor zone Thomson scattering diagnostic has been recently developed at the Budker Institute of Nuclear Physics (Novosibirsk, Russia). The small power (~10-8W) and short duration (~3-5 ns) are the main technical problems of the diagnostic. For detection and recording such low level signals the prototype of uniquely designed complex data acquisition system was developed. This system consists of 48 photodetector modules with 0-200MHz bandwidth, 48 simultaneously sampling ADC modules and synchronization subsystem. The photodetector modules are based on avalanche photodiodes and extremely low noise transimpedance preamplifiers. ADC modules include fast analog to digital convertors and digital units based on the Field-Programmable Gate Array for data processing and storage. The synchronization subsystem is used to form triggering pulses and to organize the simultaneously mode of ADC modules operation. Features of the system allow detection and recording short duration (3-5 ns) scattered pulses with 2GHz sampling rate and 10-bit total resolution in oscilloscope mode. At present, the system is tested on GLOBUS tokamak (St. Petersburg, Russia).

A 32-Channel High-Speed Simultaneously Sampling Data Acquisition System

The system is intended for recording data in the multichannel diagnostic sections of experimental plasma facilities. It contains eight four-channel modules that record the shapes of single pulse signals, a controller module of the system bus of the crate, a fiber-optic communication line, and an interface card for connection to the ISA bus of a personal computer. The recording modules are based on 12-bit analog-to-digital converters (ADCs) with a sampling frequency of up to 50 MHz, ensuring a conversion accuracy equal to the least significant bit in a band of the input signal of up to 20 MHz. The ADC samples are fixed in 32-Kword/channel buffer storage units with a page organization. The current values of the amplitude of the input signals in all of the recording channels are measured simultaneously with a time jitter of no more than 0.2 ns. The software selects an amplitude conversion scale and a zero offset voltage value for each recording channel, as well as the current value of the sampling frequency for all the channels.

Note: Spectrometer with multichannel photon-counting detector for beam emission spectroscopy in magnetic fusion devices

A spectrometer based on a linear array photomultiplier tube (PMT) has been developed and calibrated. A 0.635 m focal length Czerny-Turner monochromator combined with a coupling optics provides an image of a narrow 0.5 nm spectral range with a resolution of 0.015 nm/channel on a 32-anode PMT. The system aims at spectroscopy of D(α) or H(α) lines emitted by a diagnostic atomic beam in a plasma (primarily a motional Stark effect diagnostics). To record a low photon flux of ∼10(6) s(-1) per channel with the time resolution of 100 μs, a pulse counting approach has been used. Wideband amplifiers scale single-electron pulses and transmit them to a digital data processing core hardwired in a programmable logic matrix. Calibrations have shown that the aberration-limited instrument function fits to a single detector channel of 1 mm width. Pilot results of passive measurements of D(α) light emission from the plasma confined in a magnetic trap are presented.

Multifunction fast recorder ADC12500 for plasma diagnostics

The ADC12500 recorder is oriented for designing of multichannel synchronous measuring systems and data preprocessing in the real-time mode. It includes two 12-bit analog-to-digital conversion sections operating with 500 MHz sampling frequency. The recorder ADC12500 can programmatically adapted to a wide spectrum of the applications.

Thomson scattering diagnostic data acquisition systems for modern fusion systems

Uniquely designed complex data acquisition system for Thomson scattering diagnostic was developed. It allows recording short duration (3-5 ns) scattered pulses with 2GHz sampling rate and 10-bit total resolution. The system consists up to 48 photo detector modules with 0-200MHz bandwidth, 1-48 simultaneously sampling ADC modules and synchronization subsystem. The photo detector modules are based on avalanche photodiodes and ultra-low noise transimpedance amplifiers. ADC modules include fast analog to digital convertors and digital units based on the Field-Programmable Gate Array for data processing and storage. The synchronization subsystem is used to form triggering pulses and to organize the simultaneously mode of ADC modules operation.

Data acquisition system prototype for Thomson scattering diagnostic of ITER divertor

We present a prototype of the data acquisition system for Thomson scattering diagnostic of ITER divertor. The system allows the recording of the plasma scattered laser radiation beams. They have 1064 nm wavelength, 3 ns duration and 100 Hz - 1 kHz repetition rate. The system consists of 48 simultaneous sampling ADC modules with 10 bit total resolution and 2 GHz sampling rate. The digital units of the ADC modules use FPGA (Field-Programmable Gate Array) for data processing and storage.

A 128-Channel Simultaneously Sampling Data Acquisition System for the Diagnostic Complex of Experimental Plasma Facilities

The simultaneously sampling data acquisition system contains 16 eight-channel modules, which record the shapes of single pulse signals, and the controller module of the system bus of the Eurocrate, which interacts with the basic computer of the diagnostic complex via an Ethernet-FX communication line supported by TCP/IP protocols. The recording modules are based on 12-bit analog-to-digital converters (ADC). The ADC samples are fixed in buffer storage units with a capacity of up to 1 Mword/channel. The current amplitudes of the input signals are measured simultaneously in all recording channels with a time jitter of ∼3 ns. The maximum sampling frequency is below 4 MHz.

A 64-Channel Data Acquisition System for Heterodyne Interferometric Plasma Density Diagnostics

The backbone of the system is an eight-channel recording module based on a unique circuit of a precision phase detector with a resolution of <0.5 mrad at a 1-MHz carrier frequency and in a 0- to 500-kHz modulation band. The dynamic range of each channel of the recording module varies from –250 to +250 rad.

DAQ system for profile recording of ns thomson rcattering pulses

Thomson scattering (TS) is the most accurate and useful method of measuring plasma electron temperature and density in fusion-oriented experiments. The small power (∼10−8W) and short duration (∼10 ns and less) of scattering signal are the main technical problems of the method. That is why highest requirements are made to photodetection and recording systems. Developed by Budker Institute of Nuclear Physics (Novosibirsk, Russia) fast DAQ system allows recording profiles of short duration (3-5 ns) scattered pulses in 0-200MHz bandwidth with 2GSPS rate and 12-bit resolution. The system consists of photo detector modules (with 200MHz bandwidth), fast (2GSPS) and slow (10MSPS) ADC modules and synchronization subsystem. The 48-channel version of this system was developed as a prototype for ITER (Cadarache, France) divertor Thomson scattering diagnostic. The system was tested and put into operation on GLOBUS-M tokamak (St. Petersburg, Russia).