Tommaso Bolzonella in the interest of RFX-mod group Consorzio RFX-Associazione Euratom-ENEA sulla fusione, Padova, Italy

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Resistive Wall Modes : exhibit results and systems Tommaso Bolzonella for the benefit of RFX-mod group Consorzio RFX-Associazione Euratom-ENEA sulla fusione, Padova, Italy RFX-mod Program Meeting 2009 – Padova - 20-22/01/2009 RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Summary A RWM preliminary: Five Ws (and one H) on Resistive Wall Modes Recent results on tokamak RWMs and future hot issues RFP conceivable commitments on RWM regular issues RFP systems to expand the effect on RWM explore RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

What are RWMs? Resistive Wall Modes are MHD hazards that begins from the perfect wrinkle when a resistive divider is encompassing the plasma. Their principle trademark is that their development rate relies on upon the average infiltration time of the uninvolved limits, i.e. it is much slower than other run of the mill MHD or half breed timscales (  control!). (B. Alper, et al., PPCF, 1989) (P.R. Brunsell, et al., Phys. Plasmas, 2003) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

When were they found and Who fears RWMs? After their first trial recognizable proof done on a RFP (HBTX1C in Culham, 1989, i.e. 20 years prior: upbeat commemoration RWMs !), since mid 90's their study turned out to be extremely well known additionally among the tokamak group as beta constraining hazards. On the RFP side rather, the intrigue stayed "calm" till the new thousand years, when information and examinations from T2R in Stockholm set off a course of new imperative results on RWM material science and, specifically, on their dynamic control. (A. Garofalo, et al., Phys. Plasmas, 1999) (P.R. Brunsell, et al., PRL, 2004) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Why are we worried about RWMs? In the tokamak case, RWMs speak to one of the significant constraining MHD marvels in Advanced Tokamak administrations. In the RFP case a set RWMs is constantly insecure when the release term surpasses the entrance time of the detached limit. This implies any present of future RFP willing to investigate long release situations needs to adapt to RWMs. At present RWMs are the most unsafe troublesome flimsiness for a design generally vigorously interruption free. RFX-mod release #18542 is ended by a non-controlled (deliberately) RWM. RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Where would we be able to discover RWMs? Regardless of the possibility that RWMs can be found in both tokamaks and RFPs, they show up with some critical contrasts: In the tokamak they develop as weight driven, full hazards. In the RFP they develop as present driven, non-resounding insecurities. In tokmaks RWM seem fundamentally as n=1 modes, with various m parts. In RFPs they show up as m=1 modes, with a n range that relies on upon the particular q profile. As a consequence of their significance, numerous offices (both tokamaks and RFPs) have or are developping dynamic devices for RWM control. This is specifically valid for the following tokamak era, see for instance KSTAR and JT-60SA. RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

How would we be able to control RWMs? This is obviously the essential question… There are fundamentally two principle ways: Indirect control: since plasma turn stabilizingly affects RWM, by supporting it (blunder field control, energy infusion, … ) likewise RWM can be controlled. This works primarily on tokamaks. Coordinate control: a reasonable arrangement of dynamic loops coupled to an arrangement of sensors can input control the RWM plentifulness. This is the favored path on RFPs and will be the main control component on moderate pivoting tokamaks. (E.J. Strait, et al., Nucl. Combination, 2003) DIII-D RFX-mod RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Major present results on RWM in tokamaks Stabilization in moderate pivoting plasmas: blunder fields versus adjusted energy infusion. New, more great threshods found, however extrapolation to ITER still questionable. Significance of motor dissemination instruments Development of new numerical apparatuses (counting 3D impacts) Development of more productive control programming projects (M. Takechi, et al., PRL, 2007) Similar results in (H. Reimerdes, et al., PRL, 2007) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Major residual issues on RWM in tokamaks ITER (DEMO) stream revolution? RWM security edge and 3D mistake fields Mode inflexibility Kinetic impacts on RWM steadiness Optimal dynamic curl framework geometry Optimal sensor sort and area Optimal control calculations RWM ID (transaction with NTMs) RWM activating by other MHD occasions (ELMs, fishbones, quick particles hazards, … ) (P. Thomas, et al., Geneva, IAEA-FEC, 2008) (M. Okabayashi, et al., Geneva, IAEA-FEC, 2008) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Major present headings on RWM in RFPs Many subjects normal to RFPs and tokamaks! Settled and analyzed phenomenology Clear information for code benchmarking Experimental confirmation of plasma turn impact on RWM development rate, hunt down conceivable dispersal instruments Advanced control calculations execution and test Resonant Field Amplification concentrates on (impact of blunder fields and of non-streamlined control) Mode inflexibility (M. Okabayashi, et al., PPCF, 2002) (H. Reimerdes, et al., PRL, 2004) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Benchmarking ITER steadiness code against RFX estimations ITER expectation codes require benchmarking against trial information CARMA (MARSF + CARIDDI) is a MHD perfect code combined with a discretionary 3D attractive limit Used to evaluate part of 3D impacts for security forecasts (openings, augmentations..) and contrast and 2D forecasts RFX-mod information (n=5 RWM) used to approve the code g (1/s) CARMA 3D 2D code n=4 F parameter (F. Villone et al., PRL, 2008) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella 2008 IAEA Fusion Energy Conference, Geneva - P. Martin

Advanced RWM control and mode un-locking Active pivot of non-thunderous divider bolted RWM is prompted by applying complex increases (keeping the mode at the sought steady sufficiency) RWM adequacy RWM stage (T. Bolzonella, V. Igochine et al., PRL, 2008) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

One all the more thing… RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella 2008 IAEA Fusion Energy Conference, Geneva - P. Martin

How would we be able to study mode inflexibility? The MHD criticism control framework can be intentionally " minimized " both in power and number of curls, to study tokamak-significant issues The impact of diminished accessible power Effects of mode non-unbending nature with a lessened arrangement of loops Interaction amongst RWMs and Tearing Modes (TM) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella 2008 IAEA Fusion Energy Conference, Geneva - P. Martin

How would we be able to study mode unbending nature? The MHD input control framework can be intentionally " minimized " both in power and number of curls, to study tokamak-pertinent issues The impact of diminished accessible power Effects of mode non-inflexibility with a lessened arrangement of loops Interaction amongst RWMs and Tearing Modes (TM) RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella 2008 IAEA Fusion Energy Conference, Geneva - P. Martin

Can it work ? With full control (192 dynamic loops) on all the fourier segments RFX-mod can work up to 1.8 MA, taking care of something like 30MW of ohmic power without limiters or divertors. What woud happen minimizing the control framework? RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Different activity on various MHD instablities Full control (192 dynamic loops) on all the fourier parts yet one RWM Reduced control (minimized dynamic curl cluster) just on the objective RWM. The determination is finished by the product control inside the process duration. RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Different activity on various MHD instablities Full control (192 dynamic curls) on all the fourier parts however one RWM Reduced control (minimized dynamic loop cluster) just on the objective RWM. The determination is finished by the product control inside the process duration. RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Different activity on various MHD instablities Full control (192 dynamic loops) on all the fourier parts yet one RWM Reduced control (minimized dynamic curl exhibit) just on the objective RWM. The choice is finished by the product control inside the process duration. RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella

Comments and conclusions RWM studies are basic field for tokamak and RFPs and composed activities speak to an extraordinary open door for complementary advantages. A few regions of basic intrigue can be recognized and in some of them RFPs can add to ITER applicable points. Future upgrades could be helpful, e.g. in the indicative region (plasma stream, current profiles, … ) and in the numerical displaying. Critical strides on those bearings are as of now advancing. RFX-mod abilities are splendidly suited to think about a large number of the most blazing issues on RWMs! RFX-mod Program Workshop, 20-22/01/09, Padova - T. Bolzonella