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TJ-II:Excitation of zonal flow oscillations by energetic particles: Difference between revisions
TJ-II:Excitation of zonal flow oscillations by energetic particles (view source)
Revision as of 19:01, 22 January 2017
, 22 January 2017Added reference structure
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'''Motivation''' | '''Motivation''' | ||
In stellarators the zonal flows (ZF) undergo several oscillations depending on the magnetic geometry and the plasma conditions. First, a Geodesic Acoustic Mode (GAM) oscillation, similar to that in tokamaks, appears, whose collisionless damping strongly depends on the rotational transform. A new oscillation, at a lower frequency, recently discovered theoretically | In stellarators the zonal flows (ZF) undergo several oscillations depending on the magnetic geometry and the plasma conditions. First, a Geodesic Acoustic Mode (GAM) oscillation, similar to that in tokamaks, appears, whose collisionless damping strongly depends on the rotational transform. A new oscillation, at a lower frequency, recently discovered theoretically <ref>Mishchenko PoP 2008</ref>, appears in stelallarators that is not present in quasisymmetric devices. In TJ-II, both oscillations have been found in simulations <ref>Sánchez PPCF 2013</ref> and the low frequency one has been identified for the first time during pellet injection experiments <ref>Alonso PRL 2017</ref>. Other experimental evidences appear to be related to zonal flow oscillations, both low frequency <ref>Pedrosa PoP 2008</ref> and GAM <ref>Castejón PPCF 2016</ref>. | ||
According to gyrokinetic simulations, the GAM and LFO oscillations are damped in the TJ-II geometry (even collisionlessly) and the necessary driving mechanism has not been identified so far. The turbulence can drive (non-linearly) these oscillations, but it is not the only option as driving mechanism. | According to gyrokinetic simulations, the GAM and LFO oscillations are damped in the TJ-II geometry (even collisionlessly) and the necessary driving mechanism has not been identified so far. The turbulence can drive (non-linearly) these oscillations, but it is not the only option as driving mechanism. | ||
In tokamaks it has been found that energetic particles can drive the GAM oscillation (EGAMs) | In tokamaks it has been found that energetic particles can drive the GAM oscillation (EGAMs) <ref>Zarzoso PRL 2013 and reference therein</ref>, but in stellarators there are less evidences <ref>Sun EFL 2016</ref> and the oscillation fauna is wider than in tokamaks. | ||
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Preferred dates: (format dd-mm-yyyy) | Preferred dates: (format dd-mm-yyyy) | ||
== References == | |||
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