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The implementation of magnetics verification in EAST plasma control system
Fusion Engineering and Design 87 (2012) 1997–2001
Contents lists available at SciVerse ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
The implementation of magnetics verification in EAST plasma control system R.R. Zhang a,∗ , B.J. Xiao a , Z.P. Luo a , Q.P. Yuan a , M.L. Walker b , B. Shen a a b
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, China General Atomics, DIII-D National Fusion Facility, San Diego, CA, USA
a r t i c l e
i n f o
Article history: Available online 22 May 2012 Keywords: Tokamak EAST plasma control system Magnetics verification
a b s t r a c t Experimental advanced superconducting tokamak (EAST) is an experimental device aiming at steady state plasma operation for fusion research. The values of many discharge parameters, such as plasma shape, position and current must be directly acquired or indirectly evaluated from the magnetic measurements, so the accuracy of magnetic measurements plays an important role in reliable plasma control performance. A method for verifying the key magnetic measurements in real time for each shot is described in this paper. Such magnetics verification will prevent the discharge from a key magnetic signal failure and ensure the quality of a successful discharge. The diagnostics verification algorithm has been implemented in the plasma control system for the EAST. The implementation details and its application in the recent experiment are presented in this paper. © 2012 Elsevier B.V. All rights reserved.
1. Introduction EAST is an experimental device aiming at steady state plasma operation for fusion research. Its plasma control system [1] (EAST PCS) is adapted from DIII-D plasma control system architecture [2,3] and keeps its continuous development to meet EAST growing experimental needs. Optimum performance of a tokamak discharge needs accurate and reliable feedback control of many discharge parameters. The values of these parameters such as plasma shape, position and current must be directly acquired or indirectly evaluated from the magnetic measurements, so a high accuracy of magnetic measurements plays an important role in reliable plasma control performance. EAST key magnetic diagnostics that used in the PCS consist of current measurements for the plasma, coils and vessel, flux loops for the poloidal flux and magnetic probes for the poloidal fields. As shown in Fig. 1, 38 poloidally aligned magnetic probes and 35 flux loops are mounted on the vacuum vessel in the current EAST magnetic diagnostics configuration. Because of instrumental error such as the sensor fault or integrator abnormal drift, an acquired magnetic signal may encounter signal contamination. Daily verification routine is inevitable as this contamination occasionally occurs unexpectedly. In this paper, we propose a verification of key magnetic measurements in real time for each shot in EAST PCS. PCS compares the acquired signals of magnetic probes and flux loops with standard data. The standard data can be obtained from a reference history shot or calculated by using Green’s function method. Once one of the signals’ errors is larger
∗ Corresponding author. Tel.: +86 551 5591354; fax: +86 551 5593350. E-mail address: [email protected] (R.R. Zhang). 0920-3796/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fusengdes.2012.04.026
than the critical value that specified by the operator, PCS could trigger a protection to stop the discharge. The implementation details and experiment results are presented in Sections 2 and 3. Finally, a conclusion is given in Section 4.
2. Magnetics verification in EAST PCS 2.1. The design of magnetic measurements verification phase The magnetic signal fault can be defined as the difference between the measured magnetic and standard data. PCS reacts to fault conditions based on the specified criteria that set by the operators. To avoid disturbing the plasma, the verification should be carried out for a short period time at poloidal field coil initial magnetization phase of a discharge. PCS calculates the average errors to compare with the criteria data when the verification time is over. Once the error is larger than the tolerable value, PCS can be shifted immediately to a protection algorithm or just list all the fault signals to the operators for their attention. To avoid overheating of coils and the possible damage of the insulation layer by high end voltage, the current ramp-rate of all coils is restrained. Furthermore, to ensure least influenced by the vessel current, the verification should be carried out after all coil currents reach the designed flattop for a period much longer than the vessel field penetration time (∼25 ms). Under those conditions, according to the superposition principle of magnetic field, a magnetic diagnostic signal has the form Mj =
j
Gi ∗ Ici
(1)
1998
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
fault detection and protection [4,5]. The magnetics verification algorithm was added into the fault detection and protection algorithms for efficient discharge. Once the verification switch is on, PCS executes a single code loop continuously until the verification phase is over. For each control cycle, the verification algorithm typically performs the following steps: a. The magnetic measurement signals are acquired. The error is generated for each signal that used in the discharge control. The error can be either a relative error or absolute error. It can be generated using the following formula:
Mref − Macq or E(t) = Mref − Macq E(t) = Mref + ε
(2)
In the above formula, Mref is the standard data, either can be measured magnetic values of a history shot or calculated values by using Green’s function method. Macq is the current shot’s acquired data. ε is a very small value, to avoiding divide by zero error if |Mref | is close to zero by chance in a control cycle. b. The error E(t) and standard value |Mref | are accumulated. c. The error values are stored to be archived into PCS database. Fig. 1. EAST cross section and magnetic diagnostics distribution: closed circle, flux loops; open diamond, magnetic probes.
Here Mj is one of the key magnetic measurements used by PCS, j
either a magnet probe or flux loop. Gi is the Green’s function or
the poloidal coil currents effect on the Mj . Ici is the ith poloidal coil current. As shown in Fig. 1, EAST has 14 superconductive poloidal field coils, PF’s 7 and PF’s 9 are connected in series as PF’s 8 and 10. A total of 12 independent superconducting poloidal field coils are driven by 12 independent poloidal field power supplies, so i is 12 in the formula. It assumes by the verification method that the measurements of coil currents are accurate, thus the standard data can be calculated by using the formula (1). Due to low S/N at a weak signal level on magnetic diagnostics, PF coil currents have to be set on an appropriate level set. Different with flux loops, the poloidal coil currents effect on a magnetic probe may counteract each other. So we primarily think about how to obtain a higher strength level of magnetic probes. The least square optimization is used to specify a set of coil current levels to avoid low magnetic diagnostic measurement values. We assume that the magnetic probe values are all at a higher level, for example, 500 G, and then the optimizing coil currents can be shown in Fig. 2. Due to those causes, a verification phase was designed as shown in Fig. 2, the verification phase is from −2.4 s to −2.2 s on the graph. During the verification phase, the most magnetic probe’s calculated value can be reached greater than 200 G, and flux loops are about 2.6 Wb. PCS also stores the measured magnetic measurements into the MDSPlus database, thus not only the calculated values by using Green’s function, but also the historical measured data can be used as standard data. The experiment results by using calculated values and simulation results by using a reference history shot are all discussed in Section 3. 2.2. The control logic of magnetic measurements verification Since the first plasma was obtained in 2006, EAST PCS has served all the EAST campaigns for discharge control. Currently, the available control algorithms for EAST PCS are PF coil current control, RZIP control, plasma density control, rtefit/isoflux control,
The above steps are repeated during the whole verification ¯ ref phase, and then the average error E¯ and average standard data M of each verified signal are calculated in the next control cycle. If ¯ ref is very small, the signal may easily be drowned by background M noises. PCS compares the acquired signals with standard data at pre-specified sufficient signal–noise level. As shown in Fig. 3, the operator can specify the value of “check above this limit”. If the ¯ ref | of one signal is less than that specified value, that signal does |M not need to be verified in this discharge. There are two response scenarios in the verification algorithm. Once the trip response is enabled, PCS can list all the tripped signals in the view-log window of PCS user interface. As the error values of the magnetic signals are all stored in the MDSPlus database, it’s convenient to know the quality of magnetic diagnostics and does not affect the plasma discharge process. For both the trip response and shape response are enabled, PCS can trigger a protection to stop the discharge if any of the key signals’ average error is larger than the critical value. Such magnetics verification will increase more reliability for the overall plasma control system.
3. Experiment and simulation results 3.1. Experiment results by using calculated values Magnetic measurements verification was implemented in the EAST plasma control system in the last campaign. For EAST shot 36749 and 36750, the calculated values by using Green’s function were used as standard data. The experiment result is shown in Fig. 4, PF coil currents had the same level set for those two shots, as shown in the right part of the figure. The responses of the verification were enabled in shot 36750, as show in the blue lines. Since the E of magnetic probe No. 20 was larger than the critical value (the critical value usually set to 3% for flux loops and 5% for magnetic probes), the trip occurred after −2.2 s and all the power supply commands were forced to zero, as shown in the red dash line in the figure. (For interpretation of the references to color in this text, the reader is referred to the web version of the article.)
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
1999
Fig. 2. Red region is the designed verification phase with all key BPs greater than 200 G, shot 36749. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
3.2. Simulation results by using a reference history shot The PCS infrastructure provides the facilities to extensively test control algorithms off-line [6]. For simulation test mode, PCS input data are provided by a “simulation server” process, so-called “data simserver”. The data simserver can provide both the acquired diagnostic data and the computed results data from a real plasma operation history shot. As EAST PCS’s minimum control cycle is 50 S, it would be a very large amount for saving all data, thus PCS only save some samples for analysis after the discharge. It means that the historical acquired magnetics data is sampled. For each control cycle in a discharge, it may not have real historical acquired diagnostic data as standard data if the algorithm using a reference history shot. For the verification method using reference history shot, the average value of the historical diagnostic data over the verification phase was used as the standard data. At the PCS setup time, PCS calculates the average value of each verified signal. During the verification phase of a discharge, PCS compares the acquired magnetic signals with those average values in every control cycle.
Fig. 3. The verification fault condition setting.
2000
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
Fig. 4. Calculated values by using Green’s function method as standard data is used, EAST shot 36749 and 36750.
Fig. 5. The acquired magnetic data of shot 36750 is used as standard data, simulation shot: 997101.
We have a simulation result by using the reference history shot as standard data. As shown in Fig. 5, the data simserver provides the experimental data of shot 36799, the acquired magnetic data of shot 36750 is obtained as standard data, PCS runs a closed loop test with the data simserver, the result is store in shot 997101. The coil currents are the same level set for those shots. As shown in Fig. 5, the black lines are the results from shot 36750 and the red ones are the simulation shot 997101. The signals’ relative errors of shot 36750 are higher then shot 997101, these results indicate that
better verification performance can be obtained by using a proper history shot. 4. Summary and discussion Magnetics verification was already tested and implemented in the EAST last campaign. It can list all the tripped signals to the operators for their attention and response to a protection algorithm. Such magnetics verification can prevent the discharge
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
from a key magnetic signal failure and increase reliability for the overall plasma control system. The results show that the verification algorithm is essential for plasma control. The simulation results indicate that using a reference history shot as standard data is a better choice. At present PCS only check and verify signals of the flux loops and magnetic probes, as plasma electron density is also an extremely important physics parameter in tokamak experiment, more signals such as HCN (hydrogen cyanide)/DCN (deuterium cyanide) far-infrared laser interferometer signals for measuring plasma electron density could be included in the PCS verification in the future. Acknowledgments This work supported by National Natural Science Foundation of China (No. 10835009) and the 973 project from the Chinese Ministry of Sciences and Technology (No. 2009GB103000). The authors would like to acknowledge all of the colleagues of the Computer
2001
Application Division at the Institute of Plasma Physics, Chinese Academy of Sciences and for their contributions. References [1] B. Xiao, D. Humphreys, M. Walker, A. Hyatt, J. Leuer, D. Mueller, et al., EAST plasma control system, Fusion Engineering and Design 83 (2008) 181–187. [2] D. Humphreys, J. Ferron, A. Hyatt, R. Lahaye, J. Leuer, B. Penaflor, et al., DIIID integrated plasma control solutions for ITER and next-generation tokamaks, Fusion Engineering and Design 83 (2008) 193–197. [3] B. Penaflor, J. Ferron, M. Walker, D. Humphreys, J. Leuer, D. Piglowski, et al., Worldwide collaborative efforts in plasma control software development, Fusion Engineering and Design 83 (2008) 176–180. [4] J.R. Ferron, M.L. Walker, L.L. Lao, H.E. St. John, D.A. Humphreys, J.A. Leuer, Real time equilibrium reconstruction for tokamak discharge control, Nuclear Fusion 38 (1998) 1055. [5] B.J. Xiao, Z.S. Ji, B. Shen, G.M. Li, H.Z. Wang, F. Wang, et al., Current status of EAST plasma control and data acquisition, IEEE Transactions on Nuclear Science 57 (2010) 510–514. [6] J.R. Ferron, B. Penaflor, M.L. Walker, J. Moller, D. Butner, A flexible software architecture for tokamak discharge control systems, in: SOFE 95, Seeking a New Energy Era, 16th IEEE/NPSS Symposium, Fusion Engineering 872 (1995) 870–873.
Contents lists available at SciVerse ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
The implementation of magnetics verification in EAST plasma control system R.R. Zhang a,∗ , B.J. Xiao a , Z.P. Luo a , Q.P. Yuan a , M.L. Walker b , B. Shen a a b
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, China General Atomics, DIII-D National Fusion Facility, San Diego, CA, USA
a r t i c l e
i n f o
Article history: Available online 22 May 2012 Keywords: Tokamak EAST plasma control system Magnetics verification
a b s t r a c t Experimental advanced superconducting tokamak (EAST) is an experimental device aiming at steady state plasma operation for fusion research. The values of many discharge parameters, such as plasma shape, position and current must be directly acquired or indirectly evaluated from the magnetic measurements, so the accuracy of magnetic measurements plays an important role in reliable plasma control performance. A method for verifying the key magnetic measurements in real time for each shot is described in this paper. Such magnetics verification will prevent the discharge from a key magnetic signal failure and ensure the quality of a successful discharge. The diagnostics verification algorithm has been implemented in the plasma control system for the EAST. The implementation details and its application in the recent experiment are presented in this paper. © 2012 Elsevier B.V. All rights reserved.
1. Introduction EAST is an experimental device aiming at steady state plasma operation for fusion research. Its plasma control system [1] (EAST PCS) is adapted from DIII-D plasma control system architecture [2,3] and keeps its continuous development to meet EAST growing experimental needs. Optimum performance of a tokamak discharge needs accurate and reliable feedback control of many discharge parameters. The values of these parameters such as plasma shape, position and current must be directly acquired or indirectly evaluated from the magnetic measurements, so a high accuracy of magnetic measurements plays an important role in reliable plasma control performance. EAST key magnetic diagnostics that used in the PCS consist of current measurements for the plasma, coils and vessel, flux loops for the poloidal flux and magnetic probes for the poloidal fields. As shown in Fig. 1, 38 poloidally aligned magnetic probes and 35 flux loops are mounted on the vacuum vessel in the current EAST magnetic diagnostics configuration. Because of instrumental error such as the sensor fault or integrator abnormal drift, an acquired magnetic signal may encounter signal contamination. Daily verification routine is inevitable as this contamination occasionally occurs unexpectedly. In this paper, we propose a verification of key magnetic measurements in real time for each shot in EAST PCS. PCS compares the acquired signals of magnetic probes and flux loops with standard data. The standard data can be obtained from a reference history shot or calculated by using Green’s function method. Once one of the signals’ errors is larger
∗ Corresponding author. Tel.: +86 551 5591354; fax: +86 551 5593350. E-mail address: [email protected] (R.R. Zhang). 0920-3796/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fusengdes.2012.04.026
than the critical value that specified by the operator, PCS could trigger a protection to stop the discharge. The implementation details and experiment results are presented in Sections 2 and 3. Finally, a conclusion is given in Section 4.
2. Magnetics verification in EAST PCS 2.1. The design of magnetic measurements verification phase The magnetic signal fault can be defined as the difference between the measured magnetic and standard data. PCS reacts to fault conditions based on the specified criteria that set by the operators. To avoid disturbing the plasma, the verification should be carried out for a short period time at poloidal field coil initial magnetization phase of a discharge. PCS calculates the average errors to compare with the criteria data when the verification time is over. Once the error is larger than the tolerable value, PCS can be shifted immediately to a protection algorithm or just list all the fault signals to the operators for their attention. To avoid overheating of coils and the possible damage of the insulation layer by high end voltage, the current ramp-rate of all coils is restrained. Furthermore, to ensure least influenced by the vessel current, the verification should be carried out after all coil currents reach the designed flattop for a period much longer than the vessel field penetration time (∼25 ms). Under those conditions, according to the superposition principle of magnetic field, a magnetic diagnostic signal has the form Mj =
j
Gi ∗ Ici
(1)
1998
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
fault detection and protection [4,5]. The magnetics verification algorithm was added into the fault detection and protection algorithms for efficient discharge. Once the verification switch is on, PCS executes a single code loop continuously until the verification phase is over. For each control cycle, the verification algorithm typically performs the following steps: a. The magnetic measurement signals are acquired. The error is generated for each signal that used in the discharge control. The error can be either a relative error or absolute error. It can be generated using the following formula:
Mref − Macq or E(t) = Mref − Macq E(t) = Mref + ε
(2)
In the above formula, Mref is the standard data, either can be measured magnetic values of a history shot or calculated values by using Green’s function method. Macq is the current shot’s acquired data. ε is a very small value, to avoiding divide by zero error if |Mref | is close to zero by chance in a control cycle. b. The error E(t) and standard value |Mref | are accumulated. c. The error values are stored to be archived into PCS database. Fig. 1. EAST cross section and magnetic diagnostics distribution: closed circle, flux loops; open diamond, magnetic probes.
Here Mj is one of the key magnetic measurements used by PCS, j
either a magnet probe or flux loop. Gi is the Green’s function or
the poloidal coil currents effect on the Mj . Ici is the ith poloidal coil current. As shown in Fig. 1, EAST has 14 superconductive poloidal field coils, PF’s 7 and PF’s 9 are connected in series as PF’s 8 and 10. A total of 12 independent superconducting poloidal field coils are driven by 12 independent poloidal field power supplies, so i is 12 in the formula. It assumes by the verification method that the measurements of coil currents are accurate, thus the standard data can be calculated by using the formula (1). Due to low S/N at a weak signal level on magnetic diagnostics, PF coil currents have to be set on an appropriate level set. Different with flux loops, the poloidal coil currents effect on a magnetic probe may counteract each other. So we primarily think about how to obtain a higher strength level of magnetic probes. The least square optimization is used to specify a set of coil current levels to avoid low magnetic diagnostic measurement values. We assume that the magnetic probe values are all at a higher level, for example, 500 G, and then the optimizing coil currents can be shown in Fig. 2. Due to those causes, a verification phase was designed as shown in Fig. 2, the verification phase is from −2.4 s to −2.2 s on the graph. During the verification phase, the most magnetic probe’s calculated value can be reached greater than 200 G, and flux loops are about 2.6 Wb. PCS also stores the measured magnetic measurements into the MDSPlus database, thus not only the calculated values by using Green’s function, but also the historical measured data can be used as standard data. The experiment results by using calculated values and simulation results by using a reference history shot are all discussed in Section 3. 2.2. The control logic of magnetic measurements verification Since the first plasma was obtained in 2006, EAST PCS has served all the EAST campaigns for discharge control. Currently, the available control algorithms for EAST PCS are PF coil current control, RZIP control, plasma density control, rtefit/isoflux control,
The above steps are repeated during the whole verification ¯ ref phase, and then the average error E¯ and average standard data M of each verified signal are calculated in the next control cycle. If ¯ ref is very small, the signal may easily be drowned by background M noises. PCS compares the acquired signals with standard data at pre-specified sufficient signal–noise level. As shown in Fig. 3, the operator can specify the value of “check above this limit”. If the ¯ ref | of one signal is less than that specified value, that signal does |M not need to be verified in this discharge. There are two response scenarios in the verification algorithm. Once the trip response is enabled, PCS can list all the tripped signals in the view-log window of PCS user interface. As the error values of the magnetic signals are all stored in the MDSPlus database, it’s convenient to know the quality of magnetic diagnostics and does not affect the plasma discharge process. For both the trip response and shape response are enabled, PCS can trigger a protection to stop the discharge if any of the key signals’ average error is larger than the critical value. Such magnetics verification will increase more reliability for the overall plasma control system.
3. Experiment and simulation results 3.1. Experiment results by using calculated values Magnetic measurements verification was implemented in the EAST plasma control system in the last campaign. For EAST shot 36749 and 36750, the calculated values by using Green’s function were used as standard data. The experiment result is shown in Fig. 4, PF coil currents had the same level set for those two shots, as shown in the right part of the figure. The responses of the verification were enabled in shot 36750, as show in the blue lines. Since the E of magnetic probe No. 20 was larger than the critical value (the critical value usually set to 3% for flux loops and 5% for magnetic probes), the trip occurred after −2.2 s and all the power supply commands were forced to zero, as shown in the red dash line in the figure. (For interpretation of the references to color in this text, the reader is referred to the web version of the article.)
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
1999
Fig. 2. Red region is the designed verification phase with all key BPs greater than 200 G, shot 36749. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
3.2. Simulation results by using a reference history shot The PCS infrastructure provides the facilities to extensively test control algorithms off-line [6]. For simulation test mode, PCS input data are provided by a “simulation server” process, so-called “data simserver”. The data simserver can provide both the acquired diagnostic data and the computed results data from a real plasma operation history shot. As EAST PCS’s minimum control cycle is 50 S, it would be a very large amount for saving all data, thus PCS only save some samples for analysis after the discharge. It means that the historical acquired magnetics data is sampled. For each control cycle in a discharge, it may not have real historical acquired diagnostic data as standard data if the algorithm using a reference history shot. For the verification method using reference history shot, the average value of the historical diagnostic data over the verification phase was used as the standard data. At the PCS setup time, PCS calculates the average value of each verified signal. During the verification phase of a discharge, PCS compares the acquired magnetic signals with those average values in every control cycle.
Fig. 3. The verification fault condition setting.
2000
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
Fig. 4. Calculated values by using Green’s function method as standard data is used, EAST shot 36749 and 36750.
Fig. 5. The acquired magnetic data of shot 36750 is used as standard data, simulation shot: 997101.
We have a simulation result by using the reference history shot as standard data. As shown in Fig. 5, the data simserver provides the experimental data of shot 36799, the acquired magnetic data of shot 36750 is obtained as standard data, PCS runs a closed loop test with the data simserver, the result is store in shot 997101. The coil currents are the same level set for those shots. As shown in Fig. 5, the black lines are the results from shot 36750 and the red ones are the simulation shot 997101. The signals’ relative errors of shot 36750 are higher then shot 997101, these results indicate that
better verification performance can be obtained by using a proper history shot. 4. Summary and discussion Magnetics verification was already tested and implemented in the EAST last campaign. It can list all the tripped signals to the operators for their attention and response to a protection algorithm. Such magnetics verification can prevent the discharge
R.R. Zhang et al. / Fusion Engineering and Design 87 (2012) 1997–2001
from a key magnetic signal failure and increase reliability for the overall plasma control system. The results show that the verification algorithm is essential for plasma control. The simulation results indicate that using a reference history shot as standard data is a better choice. At present PCS only check and verify signals of the flux loops and magnetic probes, as plasma electron density is also an extremely important physics parameter in tokamak experiment, more signals such as HCN (hydrogen cyanide)/DCN (deuterium cyanide) far-infrared laser interferometer signals for measuring plasma electron density could be included in the PCS verification in the future. Acknowledgments This work supported by National Natural Science Foundation of China (No. 10835009) and the 973 project from the Chinese Ministry of Sciences and Technology (No. 2009GB103000). The authors would like to acknowledge all of the colleagues of the Computer
2001
Application Division at the Institute of Plasma Physics, Chinese Academy of Sciences and for their contributions. References [1] B. Xiao, D. Humphreys, M. Walker, A. Hyatt, J. Leuer, D. Mueller, et al., EAST plasma control system, Fusion Engineering and Design 83 (2008) 181–187. [2] D. Humphreys, J. Ferron, A. Hyatt, R. Lahaye, J. Leuer, B. Penaflor, et al., DIIID integrated plasma control solutions for ITER and next-generation tokamaks, Fusion Engineering and Design 83 (2008) 193–197. [3] B. Penaflor, J. Ferron, M. Walker, D. Humphreys, J. Leuer, D. Piglowski, et al., Worldwide collaborative efforts in plasma control software development, Fusion Engineering and Design 83 (2008) 176–180. [4] J.R. Ferron, M.L. Walker, L.L. Lao, H.E. St. John, D.A. Humphreys, J.A. Leuer, Real time equilibrium reconstruction for tokamak discharge control, Nuclear Fusion 38 (1998) 1055. [5] B.J. Xiao, Z.S. Ji, B. Shen, G.M. Li, H.Z. Wang, F. Wang, et al., Current status of EAST plasma control and data acquisition, IEEE Transactions on Nuclear Science 57 (2010) 510–514. [6] J.R. Ferron, B. Penaflor, M.L. Walker, J. Moller, D. Butner, A flexible software architecture for tokamak discharge control systems, in: SOFE 95, Seeking a New Energy Era, 16th IEEE/NPSS Symposium, Fusion Engineering 872 (1995) 870–873.