TJ-II:Magnetic configuration: Difference between revisions

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Created page with "The magnetic configurations of the low shear stellarator TJ-II in vacuum are specified by a label consisting of 3 numbers: X_Y_Z. These numbers represent the currents flowing in the external coils. * X is the current in the helical coil (HX, in kA) times 10 * Y is the current in the circular coil (CC, in kA) times 10 * Z is the current in the vertical field coil (VF, in kA) times 10 The current in the toroidal field coils (TF) is not specified,..."
 
 
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The plasma size r<sub>av</sub> increases with <math>I_{CC}+I_{HX}</math>, so that reasonably-sized plasmas are limited to the upper right triangle of this diagram.
The plasma size r<sub>av</sub> increases with <math>I_{CC}+I_{HX}</math>, so that reasonably-sized plasmas are limited to the upper right triangle of this diagram.


Only some of the available range of configurations has been explored experimentally, as in the so-called well scan experiments<ref>A.M. de Aguilera, F. Castejón, E. Ascasíbar, E. Blanco, E. de la Cal, C. Hidalgo, B. Liu, A. López-
Only part of the available range of configurations has been explored experimentally. One can cite:
* The so-called well scan experiments<ref>J. Castellano, J. Jiménez, C. Hidalgo, M. Pedrosa, A. Fraguas, I. Pastor, J. Herranz, C. Alejaldre, and the TJ-II Team. ''Magnetic well and instability thresholds in the TJ-II stellarator''. [[doi:10.1063/1.1430435|Phys. Plasmas, 9(2):713,2002]].</ref><ref>A.M. de Aguilera, F. Castejón, E. Ascasíbar, E. Blanco, E. de la Cal, C. Hidalgo, B. Liu, A. López-
Fraguas, F. Medina, M.A. Ochando, I. Pastor, M.A. Pedrosa, B. van Milligen, and the TJ-II Team. ''Magnetic well scan and confinement in the TJ-II stellarator''. [[doi:10.1088/0029-5515/55/11/113014|Nucl. Fusion, 55(11):113014, 2015]].</ref>.
Fraguas, F. Medina, M.A. Ochando, I. Pastor, M.A. Pedrosa, B. van Milligen, and the TJ-II Team. ''Magnetic well scan and confinement in the TJ-II stellarator''. [[doi:10.1088/0029-5515/55/11/113014|Nucl. Fusion, 55(11):113014, 2015]].</ref>.
* Shot-by-shot configuration scans at constant shear<ref>V. Vargas, D. López-Bruna, J. Herranz, and F. Castejón. ''Experimental electron heat diffusion in ECH plasmas of the TJ-II stellarator''. [[doi:10.1088/0029-5515/47/9/039|Nucl. Fusion, 47:1367, 2007]].</ref><ref>B.Ph. van Milligen, J.H. Nicolau, L. García, B.A. Carreras, C. Hidalgo, and the TJ-II Team. ''The impact of rational surfaces on radial heat transport in TJ-II''. [[doi:10.1088/1741-4326/aa611f|Nucl. Fusion, 57(5):056028, 2017]].</ref>.
* Dynamic single-shot configuration scans<ref>D. López-Bruna, J. Romero, R. Jiménez-Gómez, M. Pedrosa, M. Ochando, T. Estrada, A. López-Fraguas, F. Medina, J. Herranz, T. Kalhoff, E. Ascasíbar, A. de la Peña, F. Lapayese, and J. Alonso. ''First dynamic magnetic configuration scans in ECRH plasmas of the TJ-II heliac''. [[doi:10.1088/0029-5515/49/8/085016|Nucl. Fusion, 49:085016, 2009]].</ref><ref>J. Romero, L. Pacios, A. de la Peña, F. Lapayese, and E. Ascasíbar. ''Magnetic configuration sweep control in heliac type stellarators''. [[doi:10.1088/0029-5515/54/4/043008|Nucl. Fusion, 54:043008, 2014]].</ref>.
Furthermore, the impact of the magnetic configuration on enhanced confinement has been studied<ref>Boudewijn Philip van Milligen, Teresa Estrada, Benjamin Carreras, Luis García, and TJ-II Team. ''Importance of the rotational transform for L–H transitions in the TJ-II stellarator''. [[doi:10.3390/plasma7020024|Plasma, 7(2):446–464, 2024]].</ref><ref>B.Ph. van Milligen, I. García-Cortés, K.J. McCarthy, B.A. Carreras, L. García, A. Cappa, P. Pons-
Villalonga, T. Estrada, D. Medina-Roque, J. Hernández Sánchez, R. García, O.S. Kozachok, O.O. Chmyga, J.L. de Pablos, J.M. Barcala, A. Molinero, I. Pastor, D. Tafalla, A. de la Peña, F. Lapayese, and the TJ-II Team. ''The rotational transform and enhanced confinement in the TJ-II stellarator''. [[doi:10.1017/S0022377825100433|J. Plasma Phys., 91(4):E98, 2025]].</ref>.


== See also ==
== See also ==

Latest revision as of 08:17, 3 November 2026

The magnetic configurations of the low shear stellarator TJ-II in vacuum are specified by a label consisting of 3 numbers: X_Y_Z. These numbers represent the currents flowing in the external coils.

  • X is the current in the helical coil (HX, in kA) times 10
  • Y is the current in the circular coil (CC, in kA) times 10
  • Z is the current in the vertical field coil (VF, in kA) times 10

The current in the toroidal field coils (TF) is not specified, as it is defined implicitly by requiring that the magnetic field |B| equals 0.95 T at the magnetic axis in the relevant poloidal cross sections (where ECRH is injected) in order to ensure central power deposition.

A wide range of configurations is available. The following table lists a number of them.

Configuration rav(cm) ι(0)/2π ι(a)/2π Bm,av (T) Breson (T) Rax(0°) (m) Rax(45°) (m) Shear (%) Well (%)
0_20_13 1.139 1.185 1.194 1.033 0.9504 1.644 1.374 0.7793 5.7521E-02
0_30_15 4.228 1.518 1.698 1.019 0.9500 1.658 1.360 11.85 1.050
0_40_18 5.903 1.756 2.003 1.008 0.9505 1.671 1.347 14.09 1.217
0_50_22 6.480 1.936 2.230 0.9973 0.9502 1.682 1.336 15.17 2.481
0_60_26 8.500 2.073 2.399 0.9885 0.9502 1.692 1.326 15.70 3.218
0_70_29 7.147 2.187 2.434 0.9805 0.9503 1.701 1.317 11.30 2.985
0_80_34 6.902 2.284 2.469 0.9736 0.9506 1.710 1.308 8.084 2.735
0_90_38 6.738 2.366 2.514 0.9663 0.9503 1.719 1.299 6.269 2.534
0_100_42 12.59 2.436 2.667 0.9601 0.9505 1.727 1.291 9.493 4.643
0_110_46 10.67 2.493 2.667 0.9539 0.9503 1.734 1.284 6.980 4.554
0_120_50 12.71 2.548 2.667 0.9482 0.9504 1.742 1.276 4.683 4.272
10_20_18 2.557 1.148 1.184 1.024 0.9514 1.652 1.366 3.183 0.2469
10_30_20 6.083 1.438 1.602 1.010 0.9501 1.666 1.352 11.35 1.398
10_40_24 6.921 1.659 1.880 1.000 0.9504 1.678 1.340 13.34 2.751
10_50_27 8.140 1.826 1.997 0.9909 0.9504 1.688 1.329 9.321 3.241
10_60_31 9.350 1.965 2.183 0.9826 0.9505 1.698 1.319 11.11 3.084
10_70_35 10.10 2.077 2.288 0.9750 0.9505 1.707 1.310 10.16 3.597
10_80_38 9.810 2.174 2.371 0.9674 0.9502 1.716 1.302 9.037 3.908
10_90_42 10.54 2.257 2.434 0.9610 0.9503 1.724 1.294 7.851 4.281
10_100_47 10.21 2.327 2.482 0.9546 0.9502 1.732 1.286 6.647 4.236
10_110_51 11.11 2.395 2.547 0.9488 0.9501 1.740 1.278 6.331 5.121
10_120_55 10.04 2.451 2.565 0.9432 0.9502 1.747 1.271 4.674 4.426
20_10_21 1.213 0.7902 0.7956 1.028 0.9503 1.645 1.373 0.6830 3.7624E-02
20_20_22 3.952 1.136 1.185 1.014 0.9500 1.661 1.357 4.350 0.4717
20_30_25 6.779 1.395 1.521 1.003 0.9502 1.673 1.344 9.049 1.550
20_40_28 8.475 1.592 1.771 0.9922 0.9498 1.685 1.333 11.25 2.879
20_50_32 8.039 1.756 1.906 0.9842 0.9505 1.695 1.323 8.571 3.131
20_60_35 11.21 1.884 1.997 0.9755 0.9498 1.705 1.313 5.968 1.980
20_70_39 11.08 1.994 2.154 0.9689 0.9504 1.714 1.304 7.982 3.385
20_80_43 12.14 2.092 2.255 0.9614 0.9497 1.722 1.296 7.811 4.133
20_90_47 12.83 2.174 2.324 0.9558 0.9503 1.730 1.288 6.862 4.713
20_100_51 12.68 2.246 2.379 0.9498 0.9503 1.738 1.280 5.945 4.930
20_110_55 13.79 2.313 2.434 0.9443 0.9505 1.745 1.273 5.248 5.117
20_120_59 13.91 2.368 2.483 0.9386 0.9502 1.752 1.265 4.822 5.418
30_10_25 2.709 0.8385 0.8507 1.018 0.9501 1.654 1.363 1.452 0.1431
30_20_27 5.443 1.134 1.189 1.007 0.9514 1.669 1.349 4.847 0.7001
30_30_30 8.180 1.368 1.481 0.9956 0.9506 1.681 1.337 8.332 1.733
30_40_33 9.756 1.550 1.687 0.9860 0.9503 1.692 1.326 8.877 2.798
30_50_37 11.16 1.702 1.878 0.9779 0.9503 1.702 1.316 10.37 4.941
30_60_40 9.262 1.827 1.936 0.9706 0.9505 1.711 1.307 5.952 3.624
30_70_44 12.28 1.937 2.007 0.9631 0.9502 1.720 1.298 3.593 4.431
30_80_48 13.28 2.033 2.149 0.9567 0.9502 1.728 1.290 5.702 3.674
30_90_52 14.16 2.115 2.231 0.9504 0.9501 1.736 1.282 5.476 4.227
30_100_56 14.97 2.187 2.295 0.9448 0.9502 1.743 1.275 4.949 4.755
30_110_59 15.76 2.246 2.356 0.9391 0.9500 1.751 1.267 4.920 5.215
30_120_63 14.48 2.306 2.389 0.9343 0.9504 1.758 1.260 3.573 5.025
40_00_27 1.350 0.5464 0.5471 1.024 0.9504 1.647 1.371 0.1331 2.4768E-02
40_10_29 4.111 0.8821 0.9010 1.010 0.9510 1.663 1.355 2.152 0.2456
40_20_31 6.646 1.146 1.202 0.9975 0.9501 1.677 1.341 4.928 0.8185
40_30_34 9.328 1.354 1.452 0.9884 0.9506 1.688 1.330 7.247 1.826
40_40_37 11.15 1.523 1.646 0.9788 0.9498 1.699 1.319 8.061 2.901
40_50_41 12.66 1.666 1.797 0.9719 0.9506 1.708 1.310 7.872 4.310
40_60_44 12.34 1.786 1.927 0.9637 0.9497 1.717 1.301 7.879 5.834
40_70_48 9.734 1.894 1.963 0.9579 0.9504 1.726 1.292 3.625 3.668
40_80_52 13.96 1.986 2.067 0.9515 0.9503 1.734 1.284 4.054 3.028
40_90_56 15.39 2.062 2.156 0.9457 0.9504 1.741 1.277 4.529 3.841
40_100_60 16.40 2.132 2.232 0.9400 0.9502 1.749 1.269 4.683 4.355
40_110_64 18.12 2.199 2.288 0.9348 0.9503 1.756 1.262 4.049 4.651
40_120_68 16.81 2.256 2.327 0.9295 0.9501 1.763 1.255 3.158 4.904
50_00_31 2.818 0.6329 0.6375 1.013 0.9498 1.657 1.361 0.7286 6.1871E-02
50_10_33 5.588 0.9254 0.9532 1.001 0.9506 1.672 1.346 3.003 0.3605
50_20_36 8.222 1.160 1.216 0.9902 0.9502 1.684 1.334 4.838 1.060
50_30_39 10.67 1.352 1.435 0.9815 0.9505 1.695 1.323 6.163 2.008
50_40_42 12.44 1.508 1.609 0.9733 0.9504 1.705 1.313 6.719 2.910
50_50_46 13.94 1.644 1.758 0.9661 0.9505 1.714 1.303 6.944 4.001
50_60_49 15.09 1.757 1.887 0.9587 0.9502 1.723 1.295 7.390 6.217
50_70_53 13.03 1.855 1.955 0.9524 0.9502 1.731 1.287 5.353 5.830
50_80_56 16.73 1.949 2.004 0.9463 0.9501 1.739 1.279 2.807 4.003
50_90_60 16.70 2.011 2.101 0.9407 0.9502 1.747 1.271 4.501 3.444
50_100_64 18.15 2.090 2.183 0.9351 0.9500 1.754 1.264 4.434 3.907
50_110_68 17.53 2.154 2.223 0.9297 0.9498 1.762 1.256 3.205 4.270
50_120_72 19.13 2.213 2.288 0.9250 0.9501 1.768 1.250 3.417 4.378
60_00_35 4.247 0.7126 0.7205 1.003 0.9498 1.667 1.352 1.108 0.1270
60_10_37 6.862 0.9679 1.002 0.9934 0.9509 1.680 1.338 3.520 0.4827
60_20_40 9.669 1.179 1.240 0.9831 0.9503 1.692 1.326 5.202 1.236
60_30_43 12.01 1.354 1.435 0.9747 0.9502 1.702 1.316 5.973 2.132
60_40_46 13.48 1.500 1.593 0.9672 0.9503 1.712 1.306 6.170 2.806
60_50_50 15.36 1.627 1.732 0.9601 0.9504 1.721 1.297 6.467 3.895
60_60_53 16.79 1.734 1.851 0.9528 0.9499 1.729 1.289 6.731 5.666
60_70_57 15.88 1.829 1.934 0.9473 0.9502 1.737 1.281 5.736 6.958
60_80_61 13.66 1.918 1.968 0.9428 0.9514 1.745 1.273 2.622 4.555
60_90_64 17.29 2.009 2.063 0.9359 0.9501 1.753 1.265 2.640 1.637
60_100_68 17.62 2.049 2.122 0.9304 0.9497 1.760 1.258 3.560 3.718
60_110_72 17.50 2.118 2.177 0.9257 0.9501 1.767 1.251 2.811 4.023
60_120_76 17.78 2.174 2.222 0.9217 0.9510 1.774 1.244 2.209 4.211
70_00_39 5.731 0.7825 0.7975 0.9949 0.9497 1.675 1.343 1.908 0.2335
70_10_41 8.418 1.009 1.048 0.9860 0.9509 1.688 1.330 3.845 0.6755
70_20_44 11.09 1.201 1.265 0.9767 0.9504 1.699 1.319 5.345 1.317
70_30_47 13.41 1.361 1.441 0.9688 0.9504 1.709 1.309 5.859 2.187
70_40_51 14.99 1.496 1.591 0.9615 0.9503 1.718 1.300 6.348 2.859
70_50_54 16.87 1.617 1.712 0.9543 0.9501 1.727 1.291 5.843 3.756
70_60_57 17.89 1.718 1.823 0.9479 0.9500 1.735 1.283 6.140 4.746
70_70_61 18.26 1.812 1.928 0.9423 0.9503 1.743 1.275 6.353 6.812
70_80_65 16.37 1.896 1.962 0.9363 0.9499 1.751 1.267 3.469 5.948
70_90_68 9.135 1.980 1.988 0.9317 0.9506 1.758 1.260 0.3692 0.1186
70_100_72 18.64 2.007 2.094 0.9267 0.9506 1.765 1.253 4.327 3.356
70_110_76 18.23 2.088 2.147 0.9219 0.9507 1.772 1.246 2.792 3.707
70_120_80 17.89 2.145 2.184 0.9171 0.9506 1.779 1.239 1.846 4.043
80_00_42 7.247 0.8436 0.8697 0.9869 0.9497 1.684 1.335 3.094 0.2402
80_10_45 9.865 1.049 1.095 0.9794 0.9513 1.695 1.323 4.371 0.7359
80_20_48 12.28 1.226 1.290 0.9697 0.9500 1.706 1.312 5.206 1.327
80_30_51 14.38 1.370 1.454 0.9626 0.9503 1.715 1.303 6.088 2.102
80_40_54 16.47 1.500 1.594 0.9549 0.9497 1.724 1.294 6.263 2.799
80_50_58 17.63 1.612 1.706 0.9492 0.9503 1.733 1.285 5.842 3.329
80_60_61 18.84 1.712 1.814 0.9436 0.9507 1.741 1.277 5.984 3.990
80_70_65 19.27 1.799 1.898 0.9372 0.9501 1.749 1.269 5.555 4.728
80_80_69 17.96 1.880 1.935 0.9321 0.9503 1.756 1.262 2.921 3.774
80_90_73 13.42 1.957 1.982 0.9266 0.9500 1.764 1.254 1.312 0.6938
80_100_76 18.53 2.008 2.065 0.9220 0.9504 1.770 1.247 2.839 1.773
80_110_80 18.41 2.059 2.117 0.9176 0.9507 1.777 1.241 2.847 3.632
80_120_84 18.26 2.117 2.157 0.9122 0.9496 1.784 1.234 1.872 3.986
90_00_46 8.679 0.9022 0.9354 0.9802 0.9501 1.691 1.327 3.678 0.3981
90_10_49 11.45 1.090 1.146 0.9717 0.9502 1.702 1.315 5.148 0.8099
90_20_52 12.44 1.247 1.323 0.9640 0.9503 1.712 1.305 6.100 1.079
90_30_55 16.14 1.383 1.475 0.9571 0.9504 1.722 1.296 6.607 2.158
90_40_58 17.45 1.506 1.597 0.9499 0.9501 1.731 1.287 6.012 2.629
90_50_62 18.70 1.609 1.706 0.9438 0.9501 1.739 1.279 6.003 2.901
90_60_65 18.77 1.703 1.789 0.9381 0.9502 1.747 1.271 5.045 3.047
90_70_69 18.43 1.787 1.852 0.9324 0.9500 1.754 1.263 3.623 3.117
90_80_73 17.72 1.868 1.909 0.9269 0.9497 1.762 1.256 2.217 2.354
90_90_76 14.40 1.940 1.956 0.9221 0.9499 1.769 1.249 0.8079 0.8326
90_100_80 18.53 2.009 2.038 0.9176 0.9503 1.776 1.242 1.484 1.095
90_110_84 18.97 2.021 2.094 0.9129 0.9502 1.783 1.235 3.625 3.669
90_120_88 17.79 2.090 2.129 0.9077 0.9494 1.789 1.229 1.827 3.862
100_00_50 10.07 0.9544 0.9970 0.9732 0.9499 1.699 1.319 4.471 0.4341
100_10_53 12.78 1.127 1.186 0.9649 0.9499 1.710 1.308 5.262 0.9629
100_16_55 13.69 1.215 1.287 0.9610 0.9501 1.715 1.302 5.901 1.023
100_20_56 10.86 1.271 1.324 0.9583 0.9502 1.719 1.299 4.120 0.8295
100_22_56 15.40 1.309 1.381 0.9412 0.9362 1.722 1.296 5.552 1.648
100_24_58 15.90 1.326 1.406 0.9552 0.9499 1.722 1.295 6.105 1.792
100_26_58 16.42 1.352 1.435 0.9538 0.9499 1.724 1.293 6.137 1.888
100_28_59 17.07 1.375 1.464 0.9527 0.9501 1.726 1.291 6.475 1.983
100_30_59 17.29 1.398 1.490 0.9511 0.9500 1.728 1.289 6.561 2.075
100_32_60 17.74 1.423 1.517 0.9499 0.9499 1.730 1.288 6.596 2.165
100_36_61 18.37 1.467 1.567 0.9475 0.9501 1.733 1.284 6.819 2.183
100_40_63 18.77 1.509 1.608 0.9450 0.9500 1.736 1.281 6.553 2.304
100_44_64 19.25 1.551 1.653 0.9426 0.9500 1.740 1.278 6.569 2.360
100_48_65 19.16 1.591 1.684 0.9400 0.9500 1.743 1.275 5.807 2.555
100_50_65 19.11 1.613 1.704 0.9381 0.9501 1.745 1.274 5.628 2.649
100_55_67 19.04 1.659 1.739 0.9352 0.9500 1.749 1.270 4.839 2.808
100_56_67 18.93 1.667 1.742 0.9347 0.9501 1.750 1.269 4.522 2.692
100_60_68 19.04 1.702 1.775 0.9325 0.9500 1.753 1.266 4.326 2.720
100_64_70 18.76 1.733 1.799 0.9303 0.9500 1.756 1.263 3.774 2.676
100_68_72 18.46 1.771 1.825 0.9279 0.9494 1.759 1.259 3.080 2.452
100_70_73 18.23 1.784 1.841 0.9277 0.9500 1.760 1.258 3.166 2.452
100_80_77 16.73 1.855 1.885 0.9261 0.9532 1.767 1.251 1.617 1.818
100_90_80 13.86 1.931 1.936 0.9172 0.9494 1.774 1.244 0.2833 0.7382
100_95_82 11.27 1.967 1.964 0.9243 0.9582 1.777 1.241 -0.1435 6.8954E-02
100_105_86 16.96 2.019 2.045 0.9233 0.9617 1.783 1.235 1.268 1.425
100_110_88 18.88 2.020 2.073 0.9229 0.9634 1.786 1.232 2.618 2.366
100_120_92 17.63 2.064 2.113 0.9044 0.9501 1.794 1.224 2.379 3.790
110_00_54 11.70 1.006 1.060 0.9663 0.9498 1.706 1.312 5.370 0.4642
110_10_57 13.97 1.160 1.232 0.9593 0.9502 1.716 1.301 6.136 0.8247
110_20_60 15.75 1.298 1.372 0.9526 0.9504 1.726 1.292 5.739 1.330
110_30_63 18.56 1.415 1.516 0.9455 0.9500 1.734 1.284 7.122 1.849
110_40_66 19.50 1.521 1.622 0.9398 0.9503 1.743 1.275 6.602 1.921
110_50_70 19.07 1.618 1.696 0.9336 0.9498 1.751 1.267 4.873 2.085
110_60_73 18.32 1.702 1.761 0.9291 0.9507 1.758 1.260 3.471 2.033
110_70_77 17.13 1.782 1.816 0.9237 0.9504 1.766 1.252 1.948 1.838
110_80_81 15.56 1.853 1.871 0.9192 0.9508 1.773 1.245 0.9878 1.332
110_90_84 13.12 1.923 1.926 0.9142 0.9506 1.780 1.238 0.1639 0.5301
110_95_86 10.73 1.963 1.955 0.9095 0.9486 1.783 1.235 -0.3746 8.1449E-04
110_110_92 17.29 2.020 2.055 0.9056 0.9509 1.793 1.225 1.768 2.045
110_120_95 17.55 2.048 2.095 0.9014 0.9510 1.799 1.219 2.314 3.774
120_00_57 13.14 1.050 1.117 0.9599 0.9497 1.714 1.305 6.304 0.4861
120_10_60 14.81 1.196 1.268 0.9534 0.9501 1.723 1.295 6.054 0.8382
120_20_63 17.57 1.323 1.409 0.9458 0.9494 1.732 1.286 6.504 1.409
120_30_67 19.50 1.435 1.539 0.9407 0.9503 1.741 1.277 7.263 1.529
120_40_70 19.38 1.534 1.621 0.9335 0.9492 1.749 1.269 5.695 1.632
120_50_74 18.34 1.621 1.684 0.9294 0.9503 1.756 1.262 3.910 1.864
120_60_77 17.24 1.703 1.743 0.9246 0.9507 1.764 1.254 2.381 1.733
120_70_81 16.02 1.780 1.803 0.9197 0.9509 1.771 1.247 1.312 1.511
120_80_84 14.49 1.850 1.860 0.9150 0.9509 1.778 1.240 0.5347 1.076
120_90_88 12.18 1.918 1.918 0.9096 0.9501 1.785 1.233 -4.1127E-02 0.3613
120_95_90 10.06 1.957 1.950 0.9071 0.9499 1.788 1.230 -0.3241 0.000
120_115_97 16.46 2.020 2.066 0.8983 0.9497 1.801 1.216 2.258 2.404
120_120_99 17.58 2.008 2.092 0.8967 0.9501 1.804 1.213 4.186 3.647

Flexibility

Flexibility diagram

The magnetic configurations of TJ-II offer ample flexibility in terms of rotational transform, plasma volume, and magnetic well, among others. The diagram shows the variation in the rotational transform as a function of ICC and IHX. The plasma size rav increases with ICC+IHX, so that reasonably-sized plasmas are limited to the upper right triangle of this diagram.

Only part of the available range of configurations has been explored experimentally. One can cite:

  • The so-called well scan experiments[1][2].
  • Shot-by-shot configuration scans at constant shear[3][4].
  • Dynamic single-shot configuration scans[5][6].

Furthermore, the impact of the magnetic configuration on enhanced confinement has been studied[7][8].

See also

References

  1. ↑ J. Castellano, J. Jiménez, C. Hidalgo, M. Pedrosa, A. Fraguas, I. Pastor, J. Herranz, C. Alejaldre, and the TJ-II Team. Magnetic well and instability thresholds in the TJ-II stellarator. Phys. Plasmas, 9(2):713,2002.
  2. ↑ A.M. de Aguilera, F. Castejón, E. Ascasíbar, E. Blanco, E. de la Cal, C. Hidalgo, B. Liu, A. López- Fraguas, F. Medina, M.A. Ochando, I. Pastor, M.A. Pedrosa, B. van Milligen, and the TJ-II Team. Magnetic well scan and confinement in the TJ-II stellarator. Nucl. Fusion, 55(11):113014, 2015.
  3. ↑ V. Vargas, D. López-Bruna, J. Herranz, and F. Castejón. Experimental electron heat diffusion in ECH plasmas of the TJ-II stellarator. Nucl. Fusion, 47:1367, 2007.
  4. ↑ B.Ph. van Milligen, J.H. Nicolau, L. García, B.A. Carreras, C. Hidalgo, and the TJ-II Team. The impact of rational surfaces on radial heat transport in TJ-II. Nucl. Fusion, 57(5):056028, 2017.
  5. ↑ D. López-Bruna, J. Romero, R. Jiménez-Gómez, M. Pedrosa, M. Ochando, T. Estrada, A. López-Fraguas, F. Medina, J. Herranz, T. Kalhoff, E. Ascasíbar, A. de la Peña, F. Lapayese, and J. Alonso. First dynamic magnetic configuration scans in ECRH plasmas of the TJ-II heliac. Nucl. Fusion, 49:085016, 2009.
  6. ↑ J. Romero, L. Pacios, A. de la Peña, F. Lapayese, and E. Ascasíbar. Magnetic configuration sweep control in heliac type stellarators. Nucl. Fusion, 54:043008, 2014.
  7. ↑ Boudewijn Philip van Milligen, Teresa Estrada, Benjamin Carreras, Luis García, and TJ-II Team. Importance of the rotational transform for L–H transitions in the TJ-II stellarator. Plasma, 7(2):446–464, 2024.
  8. ↑ B.Ph. van Milligen, I. García-Cortés, K.J. McCarthy, B.A. Carreras, L. García, A. Cappa, P. Pons- Villalonga, T. Estrada, D. Medina-Roque, J. Hernández Sánchez, R. García, O.S. Kozachok, O.O. Chmyga, J.L. de Pablos, J.M. Barcala, A. Molinero, I. Pastor, D. Tafalla, A. de la Peña, F. Lapayese, and the TJ-II Team. The rotational transform and enhanced confinement in the TJ-II stellarator. J. Plasma Phys., 91(4):E98, 2025.
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