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Controlling Plasma Merging Experiments used the PXI / The 392-Channel Simultaneous Measurement System, Japan

Contact Information

University: University of Tokyo

Team Member(s): Shuji Kamio

Faculty Advisors: Takuma Yamada

Email Address:

Country: Japan

Project Information


  Controlling Plasma Merging Experiments used the PXI / The 392-Channel Simultaneous Measurement System, Japan.


  This product is a comprehensive system to perform an essential trigger synchronous to control plasma merging experiments and collecting data of 392 channels.


  PXI-1045: 2 Units: 18 Slot Chassis,

  PXI-8108: 1 Unit: Win XP embedded Controller,

  PXI-8187: 1 Unit: Win XP embedded Controller,

  PXI 6541: 1 Unit: 32ch Digital Output

  PXI-6133: 22 Units: 8ch ADC

The Challenge:

  The important points of this system are:

  1. Able to send each signal at desired timing by easily operating multiple signals,

  2. Collecting data with operating a digitizer (including other company products).

  Currently, we are operating the system with these issues cleared.

The Solution:

1.      Background

Recently, energy problems are discussed everywhere, and this laboratory is researching spherical Tokamak plasmas for the practical application of nuclear fusion reactors.  The nuclear fusion generation research has started at the same time with the nuclear power generation, and it has already passed more than 50 years, but it has been not ready to generate electricity yet.  Currently, the most promising Tokamak-type nuclear fusion reactors need to capture high temperature plasmas by the magnetic field, and the huge reactors are required in order to meet the operating conditions.  Therefore, it costs enormous building cost so far, and this costly issue is one of the causes of not to be able to construct commercial reactors.  Accordingly, the spherical Tokamak which can capture plasmas much more economically is focused recently.  If we clear the issues such as producing and maintaining the plasmas and be able to practically operate by the spherical Tokamak, it will be possible to build compact and high power output reactors and drastically save the costs.

This device shown on Fig. 1 is positioned as a center of Japanese spherical Tokamak project research base, and it is aimed for an experimental verification of producing the spherical Tokamak plasmas by the merging, which research results greatly effect all over the world.

Producing and merging plasmas are performed by various magnetic field generation coils and gas injections, and the time for producing plasma once: Charging time 5 minutes, Plasma life 1 millisecond, and Cooling time 5 minutes, so about 10 minutes.  Since the objective of this experiment device is clarifying the physics of plasma formation, the plasma life time is very short.  In the experiment, sending trigger signals during several hundred milliseconds between the gas injection and plasma formation, and it is necessary to record the data output from the measurement device for several ten milliseconds while the plasma arcing. And it is important to process the data somewhat during the waiting time and effectively perform the necessary experiments by checking the results, and it is able to proceed on the research smoothly.

   Fig.1Plasma Merging Experiment Device UTST

2.      Assignments

This system has 2 objectives in order to perform experiments smoothly.

2.1 Sending Trigger Signals

In the experiment, it is necessary to send numerous signals at the determined timing by the magnetic field generation coils, and discharge electricity in order to produce plasmas in the vacuum vessel shown on Fig. 1. And at the same time, determine the timing of measurement start by sending signals to the each measurement device. 

2.2 Collecting Data/Display/Save 

It is necessary to display/save the data for a simple verification in order to quickly process the data in the experiment and perform the next experiment with the results.  Since this research uses a lot of channels, it is necessary to integrate the data from the several hardware and operate it with the software. Especially, this system has a huge assignment to record data simultaneously by utilizing this laboratory existing ICS made digitizer (128 channels) and linking it with the NI made digitizer.

3.      Solution

3.1 System Components

We have chosen following equipment made by NI in order to compose this system:

  PXI-1045: 2 Units: 18 Slot Chassis

  PXI-8108: 1 Unit: Win XP embedded Controller

  PXI-8187: 1 Unit: Win XP embedded Controller

  PXI-6541: 1 Unit: 32ch Digital Output

  PXI-6133: 33 Units: 8ch ADC

Also, we have used following this laboratory existing ICS made equipment:

  ICS-645: 4 Units: 32ch ADC

Regarding Assignment 2-1, be feasible by using PXI-6541.  We have set the temporal resolution to 10 microseconds, and we have pre-set in order to be able to have the 32-channel digital output waveform for 1 second. Operate with the pulsar screen shown on Fig. 2.  Send trigger pulses by the start button with determined pulse timing/width.  It is able to visually verify the pulse timing/width.  Also, the timer below the start button is showing the necessary cooling time: 5 minutes after the electricity discharge.

   Fig.2 Main Parts Signal Output Verification Screen

Regarding Assignment 2-2, be practical by controlling the ICS made ICS-645 with LabVIEW, and communicate the each control PC by the VI Server function.  Concretely, this system has following components (parts), and the measurement environment is shown on Fig. 3: 

  Main Parts Use 18 Slot Chassis PXI-1045

-        PXI-8108: Win XP embedded Controller

-        PXI-6541: 32ch Digital Output

-        PXI-6133 x16 Units: 8ch ADC

  Sub Parts Use 18 Slot Chassis PXI-1045

-        PXI-8187: Win XP embedded Controller

-        PXI-6133 x17 Units: 8ch ADC

  Other Company Made Parts

-        Win XP Installed PC

-        ICS-645 x4: 32ch ADC

    Fig.3 Each Part and Operation Displays

The system overall consists of 32-channel digital output and 392-channel analog input. We have formed the in-house laboratory LAN in order to integrate the data from each part, allocated internal IP addresses to each part of the controller PC, mounted directory of the data server (LINUX) by the SAMBA system, and made it able to save the each part data at the same location.

Also, the each part becomes the state of trigger-waiting by pushing the start button, but in the experiment we have had the necessity to push the start buttons of the Sub Parts and Other Company Made Parts to make them to the trigger-waiting states, before pushing the start button of the Main Parts. In order to solve this inconvenience, by using the VI Server function let the control panels between the each part to be able to access to the common global variables and by only pushing the start button of the Main Parts makes the other 2 parts start buttons to automatically react to become the trigger-waiting states, which we have improved it to be able to perform the experiment smoothly. And, even under the interlocking function, it is also able to perform an individual check for some reason to make them to the trigger-waiting states by pushing the start button of the Sub Parts/Other Company Made Parts.

Regarding the data save, the maximum sampling frequency is 2.5MHz, and the sampling number can be set up to 40,000.  The saved data is recorded by each part with binary format of Big Endian and leaving the 2-dimensional array itself.  Also, it is saved together the text data of the each channel information, and sampling frequency/sampling number. This system has succeeded to save the data with the common format including the data from other company made digitizers by performing the integral data save with LabVIEW.     

These DAQ screens are shown on Fig. 4.  These screens can show the waveforms immediately after collecting the data, and it is able to proceed on the experiment by verifying the results.  Also, the experiment data saved by the own format is re-readable, and it is able to verify the old waveforms immediately.

    Fig.4 Main Parts Data Verification Screen

    Fig.5Sub Parts Data Verification Screen             

    Fig.6Other Company Made Parts Data Verification Screen

3.2 Results

This system consists of 32-channel digital output and 392-channel analog input, and it has been able to control and measure plasma merging experiments easily by a single click.  The system overall is shown on Fig.7.  The measurement device of the main part in this laboratory, the 290-channel magnetic probe array is able to directly measure the magnetic surface of the plasma area, which system for simultaneous measurement of the all channels was not able to be built for a long time.  This time, we have been able to build the 392-channel data save system by introducing the PXI system and applying the controllability of the ICS made 128-channel ADC.  Therefore, it has become possible to save the all 290-channel magnetic probe signals simultaneously, and it has drastically increased the information from the plasma merging experiments.  Also, it has been able to save the spectrometry system 64-channel data to measure the ion temperatures at 8 points in the device, and it has been able to measure the state of heating the plasma by the plasma merging.  Besides this, it is able to save the Rogowski coil data to measure the each coil and perform the experiments smoothly.

   Fig.7Flow of Experiment by Developed PXI System

    Fig.8Measurement Coils in Device

    Fig.9Evolution of flux surfaces during plasma merging obtained the result of magnetic surface of the plasma merging shown on Fig.9 by the measurement coils placed within the black frames in the experiment device shown on Fig.8. This is the first successful result of the plasma merging by using the external magnetic coils.

4. Conclusion

Since we manufactured this system, it has been able to smoothly operate the experiment device and collect the data by performing the trigger synchronous and collecting the data of 392 channels.  Regarding the operation of the experiment device, it is able to easily operate the several signals and send the triggers by inputting the experiment conditions.  And for collecting the data, it has been able to collect the data of 392 channels by operating and collecting with the digitizer (including other company products).

By this system, we have been able to seek for the proper producing conditions, and it has been able to verify the first time of the state of the plasma formation/merging by the external coils based on the 290-channel magnetic probe measurement results.  At the same time, it is measuring the plasma temperature by the 64-channel spectrometry system in order to verify the initial heat by the merging.  

Through these experiments, our everyday research keeps continuing to seek a way of capturing the plasma with the spherical Tokamak, and to be able to propose a form of the future nuclear fusion reactor by using this system.

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NI Employee (retired)

Hey Shuji,

Thank you so much for your project submission into the Global NI LabVIEW Student Design Competition. It's great to see your enthusiasm for NI LabVIEW! Make sure you share your project URL ( with your peers and faculty so you can collect votes ("likes") for your project and win. If any of your friends have any questions about how to go about "voting" for your project, tell them to read this brief document ( Be sure to include NI LabVIEW on your "Products" list. If your team is interested in getting certified in LabVIEW, we are offering students who participate in our Global NI LabVIEW Student Design Competition the opportunity to achieve certification at a fraction of the cost. It's a great opportunity to test your skills and enhance your resume at the same time. Check it out:

Good luck,

Sadaf in Austin, Texas