© 2017 Hefei Institutes of Physical Science, Chinese Academy of Sciences and IOP Publishing
Printed in China and the UK
Plasma Sci. Technol. 19 (2017) 075602 (6pp)
Plasma Science and Technology
https://doi.org/10.1088/2058-6272/aa61f5
The development of data acquisition and
processing application system for RF ion
source
Xiaodan ZHANG (张小丹)1, Xiaoying WANG (王晓英)1,
Chundong HU (胡纯栋)2, Caichao JIANG (蒋才超)2,
Yahong XIE (谢亚红)2 and Yuanzhe ZHAO (赵远哲)2
1
2
Qinghai University, Xining 810016, People’s Republic of China
Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031, People’s Republic of China
E-mail: [email protected]
Received 2 December 2016, revised 17 February 2017
Accepted for publication 20 February 2017
Published 24 May 2017
Abstract
As the key ion source component of nuclear fusion auxiliary heating devices, the radio frequency
(RF) ion source is developed and applied gradually to offer a source plasma with the advantages
of ease of control and high reliability. In addition, it easily achieves long-pulse steady-state
operation. During the process of the development and testing of the RF ion source, a lot of
original experimental data will be generated. Therefore, it is necessary to develop a stable and
reliable computer data acquisition and processing application system for realizing the functions
of data acquisition, storage, access, and real-time monitoring. In this paper, the development of a
data acquisition and processing application system for the RF ion source is presented. The
hardware platform is based on the PXI system and the software is programmed on the LabVIEW
development environment. The key technologies that are used for the implementation of this
software programming mainly include the long-pulse data acquisition technology, multithreading processing technology, transmission control communication protocol, and the
Lempel–Ziv–Oberhumer data compression algorithm. Now, this design has been tested and
applied on the RF ion source. The test results show that it can work reliably and steadily. With
the help of this design, the stable plasma discharge data of the RF ion source are collected,
stored, accessed, and monitored in real-time. It is shown that it has a very practical application
significance for the RF experiments.
Keywords: RF ion source, data acquisition, data processing, TCP, LZO algorithm
(Some figures may appear in colour only in the online journal)
beam pulse width [1], which has realized collaborative injection
heating in the EAST background plasma and achieved good
results. Furthermore, with the continuing escalation of the production of fusion devices, the plasma parameters are also
improving. In order to achieve the core plasma heating and
current drive, the NBI system with high power, long charge
pulse, and safe, stable operation is the inevitable development
trend for neutral beam technology.
The MW-ion source is one of the key components of the
high-power NBI system. Its performance determines to the
indicators which the NBI system can achieve on a certain
1. Introduction
In nuclear fusion research, the neutral beam injection (NBI)
system had been designed and developed to provide the functions of auxiliary plasma heating and current drive for international fusion devices, such as the Experimental Advanced
Superconducting Tokamak (EAST), which is constructed at the
Institute of Plasma Physics, Chinese Academy of Sciences
(ASIPP). The NBI system on EAST is constructed with two
neutral beam injectors and each injector is designed to provide
2–4 MW beam power, 50–80 keV beam energy, and 10–100 s
1009-0630/17/075602+06$33.00
1
Plasma Sci. Technol. 19 (2017) 075602
X Zhang et al
acquisition and processing application system for the RF ion
source on NBI should be summarized in the paper.
degree. The NBI system is designed for a long-pulse steadystate operation. For achieving the requirements of high power
and long-pulse steady-state operation, the RF ion source on
the NBI system is developed to offer the source plasma with
the advantages [2] of having no filaments and being maintenance free, having no contamination of the accelerator,
being simple in structure, easy to control and highly reliable,
compared with the filament and arc ion source used on the
NBI at present.
The hardware platform for the development of the RF ion
source has been set up on the NBI system at ASIPP this year.
In addition, the data collection, processing, as well as visualization, play a very important role in the operation and
protection of the running of the RF ion source. A way to
control, obtain, and process the precise data generated during
the RF ion source experiments is urgently needed. Furthermore, it is also a very practical and meaningful work. Thus, it
is necessary to develop a stable and reliable computer data
acquisition and processing application system for the RF ion
source.
The computer data processing system introduced in [3] is
designed and used for the filament and arc ion source.
However, because of the difference between the control
running mode and the requirements of long-pulse steady-state
operation, it is necessary to design a new data processing
system. And compared with the old one, except for the
software development environment, the acquisition mode
based on ‘producer–consumer’ is adopted, which can adequately meet the requirements of long-pulse steady-state data
acquisition, long steady pulse of more over 3600 s [4], for
example. Now, the realization of this system will be presented
as follows.
a. The original signals should be collected accurately with
the required sampling frequency and long-pulse
(steady-state operation, at least over 1000 s) time span.
b. Meeting the needs of multiple control modes for data
acquisition. With the local control mode, the data
acquisition configurations will be set manually and read
from the local disk file. With the remote control mode,
the configurations are automatically configured by the
remote data server. Both of them should meet the
requirement that the data acquisition trigger signal can
be from the internal clock source and external hardware
system.
c. The collected data should be saved in an appropriate
format, so that it is easy to query and analyze.
d. Realizing the remote real-time monitoring of the longpulse signals when the RF ion source works in the
steady-state operation mode.
e. Uniting the network communication protocol and
structure for the interaction between different devices
in the RF data acquisition and processing system.
3. Implementation
3.1. Overall hardware architecture
The overall hardware architecture of the data acquisition and
processing application system for the RF ion source is schematically shown as figure 1 [7, 8].
There are three logically divided network levels. The data
acquisition device works on the local site, the data server
works on the server level, and the data display and monitoring
terminals work on the monitoring level. For insulating the
electricity and magnetism, as well as avoiding the attenuation
of the signals during transmission, optical fibers as a bridge
are used for the communication between the different devices
on different layers through switchers.
The data acquisition device is composed of a PXI
extensible chassis for running PXI data acquisition cards
(PXI6289) and the software platform is based on the LabVIEW development environment for running application
software. The data acquisition parameters can be configured
by the data server or through the local configuration file. The
acquisition trigger signal can be from the internal clock
source of the cards or the external timing synchronization
system.
The measured physical signals of the RF ion source are
transported to the AD connector cards through the V/F
module and F/V module for the insulation between electricity
and magnetism. Then, the analog-measured signals will be
collected by the PXI cards when they receive the data
acquisition configurations and trigger signal.
Once the data acquisition is ended within a given time
period, the collected data will be compressed and transferred
to the data server to instantly store them in a database. The
2. Analysis of requirements and functions
The RF signals to be measured are acquired by the data
acquisition device. Multiple acquisition control modes (that is
to say, local and remote control acquisition mode with the
trigger signal from the internal clock source or external
hardware system) and remote real-time signal monitoring
functions should also to be offered by the data acquisition
software. Then, they are compressed by a data compression
algorithm for saving storage space and are transferred to the
data server. The corresponding interfaces are designed to be
provided by the data server for data resolution, analysis, and
remote access.
In consideration of the dispersion of computer devices on
the physical location, the distributed architecture is adopted for
the RF data acquisition and processing control system by means
of the computer network technology [5, 6]. There are three
levels, which are divided into a logical network connection, as
shown in figure 1. The data acquisition device is designed for
working on the local site. There is also a need for a data server,
which works on the middle level for saving, processing, and
querying the original data. The upper level is the interactive
interface for displaying and retrieving the experimental results.
Thus, the main requirements and functions of the whole data
2
Plasma Sci. Technol. 19 (2017) 075602
X Zhang et al
Figure 1. Overall hardware architecture.
data monitoring terminal will monitor signals in real-time and
retrieve historical experimental data from the data server
according to the discharge shot number.
3.2. Data acquisition implementation
The data acquisition device consists of PXI6289 multi-functional
cards and a PXIe-8135 master controller. The software is programmed with LabVIEW language on the Windows OS and it is
developed to meet different acquisition control modes and longpulse steady-state data acquisition. According to the experimental mode, different physical signals will be collected. Once
the data acquisition parameters (channel number, signal name,
gain, sampling frequency, and time, for example) are configured
to the PXI cards, they will start to collect the required signals as
the trigger signal arrives, otherwise they will be in a waiting
state.
Each of the PXI6289 cards has 32 independent acquisition channels. To meet the actual signal measurement
requirements of the current RF Ion source, one card is
enough. And for system expansion to meet the needs of more
measurement channels, another one or more cards will be put
into the PXI device and the software correspondingly just
Figure 2. Program algorithm flow-chart of the data acquisition.
3
Plasma Sci. Technol. 19 (2017) 075602
X Zhang et al
Figure 3. Long-pulse data acquisition based on a ‘producer–consumer’ mode.
for transporting a certain amount of the collected data at one time
to the remote monitoring terminals continuously.
needs to do some minor modifications. For the data acquisition sampling frequency, the maximum value is 625 kS/s.
The actual number of the data sampling channels and frequency will be set, by the experiment operator according to
the requirements, through the software interface.
The trigger signal can be both from the board internal
clock source and the external timing synchronization system.
If the trigger signal is from the internal clock source of the
board card, the PXI card will start the data collection immediately once the software is executed and the corresponding
acquisition thread is created. However, if the trigger signal is
from the timing synchronization system, it will wait for the
external signal for data acquisition. The hardware platform of
the timing system is also based on the PXI NI platform with a
PXI6733 digital output card. The trigger signal is a digital
signal and edge-triggered mode is adopted, which will be set
by the software interface. When the external trigger mode is
chosen, an independent thread will be created for listening to
the external trigger signal. Once the rising edge or the falling
edge of the trigger signal is captured, the data acquisition will
be started immediately.
The specific data acquisition implementation program
algorithm flow-chart is shown as figure 2.
In order to meet the requirements of long-pulse steady-state
data acquisition, the acquisition mode based on ‘producer–
consumer’ is shown, as figure 3 is adopted in the software
program.
In figure 3, through creating a stack queue, the data read
from the PXI cards are temporarily saved to the data file on
the local disk, as a ‘6289.tdms’ file, for example. Thus, it is
able to read and write simultaneously. Unless the collected
data number is equal to or more than the product of the
sampling frequency and time, the data acquisition loop will
continue. Because the disk space is usually large enough, by
using this mode, the data collection and temporary storage for
a long time span (1000 s or for a longer time) can be completed continuously.
For monitoring the long-pulse signals in real-time, an
independent thread is created with the multi-threading technology
3.3. Data processing implementation
Once the data acquisition has ended, all of the data has been
completely saved to a temporary data file. In order to store the
acquisition data to the data server with as little space as
possible and to relieve the network transmission load, the
Lempel–Ziv–Oberhumer (LZO) algorithm is adopted to deal
with the original collected data. It is a classic and lossless data
compression algorithm, where both the process of compression and decompression are very fast. In application, the LZO
compression and decompression functions programmed by
C/C++ language are prepared into a dynamic link library
(LZO.dll, for example), then we just call the LZO.dll by the
library function interface provided by the LabVIEW platform
itself. This is very convenient. Experiments show that the
space after compression can be reduced to 30% of the original
with the LZO algorithm [9].
The software will read the original data from the temporary data file, then separate each data channel and compress
them with the LZO algorithm. After the compression process,
each data channel will be given a data header for recording
the discharge shot number, channel name, unit, gain, frequency, sampling time and number, and so on, which is used
for decompressing and restoring the data to the original file by
the data monitoring application program. The LZO data file
format is shown as figure 4.
The first part is the compressed data and the second part
is the LZO data header with a predefined fixed size. Then, a
complete data file is formed and transferred to the data server
through the gigabit network. At this time, the applications
running on the remote monitoring terminals can access all the
experimental data with the current shot number. The data
server is mainly used for setting configurations, storing, and
reading the data. Its software is programmed by C/C++
language with the centos system and provides the functions of
handling the request for sending the acquisition configurations, receiving the acquisition LZO data, storing them to the
4
Plasma Sci. Technol. 19 (2017) 075602
X Zhang et al
Figure 4. LZO data file format.
Figure 5. Unified data header structure.
Figure 6. Software interface of data acquisition.
server disk, and transporting the historical collection data to
the data display and monitoring terminals according to the
query keywords of the discharge shot number.
Because of the connection-oriented protocol, every time it
will return a response signal to each other after a communication interaction to ensure the reliability of the communication [10].
On account of the network communication between the
different devices in the system, an appropriate data communication structure should be unified. Through the common
custom TCP data header, each terminal can get the services
3.4. Network communication implementation
The working mode of network communication is based on
standard transmission control protocol (TCP) with C/S mode.
5
Plasma Sci. Technol. 19 (2017) 075602
X Zhang et al
5. Conclusions
The development of a data acquisition and processing system
for the RF ion source on NBI has been presented in this paper.
As one of the key subsystems, it mainly achieved the functions of data acquisition, processing, transmission, storage,
access, and remote real-time display. Based on the research
platform of the RF ion source on NBI at ASIPP, this design
has been developed and put into application at present. It has
a very practical application significance for the RF experiments, and the experimental results have shown that the
system can work well with good reliability. For further consideration, how to analyze the RF signals automatically,
which were collected by the data acquisition device, as well
as to record and print the experimental records (such as discharge image, key configuration parameters, and the actual
values collected) automatically, still need to be realized. This
will be the subject of future research.
Figure 7. Experimental test results with 3 kW/40 s high-power
stable plasma discharge.
and specific operating instruction for this communication. In
addition, for achieving the safety and reliability of data
communication, the cyclic redundancy check algorithm is
adopted to check the correctness of the network data packet.
The unified data header structure in this paper is defined as
figure 5.
Acknowledgments
The authors gratefully acknowledge the NBI team and the
partial support of National Natural Science Foundation of
China (No. 61363019), and National Natural Science Foundation of Qinghai Province (No. 2014-ZJ-718).
4. Results
References
The hardware and software implementation of the data
acquisition and processing system for the RF ion source has
been presented in the previous sections. The final data
acquisition software interface is shown as figure 6. Through
it, the selection of the data acquisition physical channels,
sampling frequency and time, clock source and trigger source,
and acquisition control mode are set. In addition, the data
acquisition control status and real-time measured signals will
be displayed on the software interface at the same time. Now,
with the help of this design, the experiment test results of the
RF ion source testing are shown in figure 7. The original data
on the graphical interfaces are obtained from the data server
and displayed by a data display terminal.
[1] Hu C D and NBI Team 2012 Plasma Sci. Technol. 14 567
[2] Xie Y H et al 2016 Analysis and design of impedance
matching unit for radio frequency ion source ECRIS2016:
22nd Int. Workshop on ECR Ion Sources (Busan, Korea)
poster number WEPP21
[3] Zhang X D et al 2014 Plasma Sci. Technol. 16 984
[4] Li G M et al 2008 Comput. Eng. 15 17 (in Chinese)
[5] Sheng P et al 2013 Plasma Sci. Technol. 15 593
[6] Zhang X D et al 2013 Plasma Sci. Technol. 15 1254
[7] Zhang X D et al 2014 J. Fusion Energy 33 125
[8] Patel V B et al 2010 J. Phys.: Conf. Ser. 208 012009
[9] Zhang X D 2015 The design of data processing software for
key parameters of NBI control system PhD thesis Hefei,
ASIPP (in Chinese)
[10] Zhang X D et al 2015 Plasma Sci. Technol. 17 327
6