TJ-II:Transport and magnetic configuration: Difference between revisions

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* The rotational transform <ref>[http://dx.doi.org/10.1088/0029-5515/45/4/009 E. Ascasíbar et al, ''Magnetic configuration and plasma parameter dependence of the energy confinement time in ECR heated plasmas from the TJ-II stellarator'', Nucl. Fusion '''45''' (2005) 276-284]</ref>
* The rotational transform <ref>[http://dx.doi.org/10.1088/0029-5515/45/4/009 E. Ascasíbar et al, ''Magnetic configuration and plasma parameter dependence of the energy confinement time in ECR heated plasmas from the TJ-II stellarator'', Nucl. Fusion '''45''' (2005) 276-284]</ref>
* Rational surfaces <ref>[http://dx.doi.org/10.1209/0295-5075/82/65002 D. López-Bruna et al, ''Tracking magnetic resonances in the effective electron heat diffusivity of ECH plasmas of the TJ-II Heliac'', EuroPhysics Letters '''82''' (2008) 65002]</ref>
* Rational surfaces <ref>[http://dx.doi.org/10.1209/0295-5075/82/65002 D. López-Bruna et al, ''Tracking magnetic resonances in the effective electron heat diffusivity of ECH plasmas of the TJ-II Heliac'', EuroPhysics Letters '''82''' (2008) 65002]</ref>
* [[Magnetic shear]] <ref>[http://dx.doi.org/10.1088/0029-5515/44/5/008 D. López-Bruna et al, ''Effects of ohmic current in the TJ-II stellarator'', Nucl. Fusion '''44''', 5 (2004) 645-654]</ref>
* [[Magnetic shear]] <ref>[http://dx.doi.org/10.1088/0029-5515/43/6/301 J.A. Romero et al, ''Controlling confinement with induced toroidal current in the flexible Heliac TJ-II'', Nucl. Fusion '''43''' (2003) 387-392]</ref> <ref>[http://dx.doi.org/10.1088/0029-5515/44/5/008 D. López-Bruna et al, ''Effects of ohmic current in the TJ-II stellarator'', Nucl. Fusion '''44''', 5 (2004) 645-654]</ref>
* [[Magnetic well]] <ref>[http://dx.doi.org/10.1088/0741-3335/43/12A/324 C. Hidalgo et al, ''On the radial scale of fluctuations in the TJ-II stellarator'', Plasma Phys. Control. Fusion '''43''' (2001) A313-A321]</ref> <ref>[http://link.aip.org/link/?PHPAEN/9/713/1 J. Castellano et al, ''Magnetic well and instability thresholds in the TJ-II stellarator'', Phys. Plasmas '''9''' (2002) 713]</ref> <ref>[http://dx.doi.org/10.1088/0741-3335/44/12B/322 E. Ascasíbar et al, ''Confinement and stability on the TJ-II stellarator'', Plasma Phys. Control. Fusion '''44''' (2002) B307-B322]</ref>
* [[Magnetic well]] <ref>[http://dx.doi.org/10.1088/0741-3335/43/12A/324 C. Hidalgo et al, ''On the radial scale of fluctuations in the TJ-II stellarator'', Plasma Phys. Control. Fusion '''43''' (2001) A313-A321]</ref> <ref>[http://link.aip.org/link/?PHPAEN/9/713/1 J. Castellano et al, ''Magnetic well and instability thresholds in the TJ-II stellarator'', Phys. Plasmas '''9''' (2002) 713]</ref> <ref>[http://dx.doi.org/10.1088/0741-3335/44/12B/322 E. Ascasíbar et al, ''Confinement and stability on the TJ-II stellarator'', Plasma Phys. Control. Fusion '''44''' (2002) B307-B322]</ref>



Revision as of 09:59, 24 August 2009

A significant part of the research effort at TJ-II is dedicated to the study of the interaction between transport and the (flexible) magnetic configuration. [1] [2] [3] The following issues contribute to the influence of the configuration on confinement:

The picture emerging from these studies is complex. In general, the presence of low-order rational surfaces in the plasma does not seem to be deleterious for transport; rather, local reductions of transport are observed (except at very low shear). Possibly, this is associated with the formation of internal transport barriers at or near such rational surfaces. On the other hand, the reduction of the magnetic well clearly enhances turbulence levels.

References