Dynamic response of the ITER tokamak during asymmetric VDEs

Schioler, Tyge; Bachmann, Christian; Mazzone, G.; Sannazzaro, G.

doi:10.1016/j.fusengdes.2010.11.016

Cited by 29 publications

(26 citation statements)

References 1 publication

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“…The good agreement between the reduced MHD model and the full MHD models originates from the presence of a large vacuum toroidal field [18]. The formulation of the energy principle for n = 0 reveals that important stabilizing terms involving the large toroidal magnetic field (B φ ) can be minimized by choosing the following form of the plasma velocity v (or plasma displacement ξ): v = ξγ = −R 2 ∇u × ∇φ (1) where γ is the growth rate, φ is the toroidal angle and u is the velocity stream function. This condition is called "Slip Motion Condition" [19], in which the plasma moves across the large toroidal field without doing work against it.…”

Section: Discussionmentioning

confidence: 99%

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Axisymmetric simulations of vertical displacement events in tokamaks: A benchmark of M3D-C1, NIMROD, and JOREK

et al. 2020

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A benchmark exercise for the modeling of vertical displacement events (VDEs) is presented and applied to the 3D nonlinear magneto-hydrodynamic codes M3D-C 1 , JOREK and NIMROD. The simulations are based on a vertically unstable NSTX equilibrium enclosed by an axisymmetric resistive wall with rectangular cross section. A linear dependence of the linear VDE growth rates on the resistivity of the wall is recovered for sufficiently large wall conductivity and small temperatures in the open field line region. The benchmark results show good agreement between the VDE growth rates obtained from linear NIMROD and M3D-C 1 simulations as well as from the linear phase of axisymmetric nonlinear JOREK, NIMROD and M3D-C 1 simulations. Axisymmetric nonlinear simulations of a full VDE performed with the three codes are compared and excellent agreement is found regarding plasma location and plasma currents as well as eddy and halo currents in the wall.

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Section: Discussionmentioning

confidence: 99%

“…These asymmetries can lead to asymmetric forces on the vessel walls. Since asymmetric forces will lead to asymmetric stresses, and might even rotate in mechanical resonance with the vessel structures [1], they can lead to large local stresses in the vacuum vessel.…”

Section: Introductionmentioning

confidence: 99%

Axisymmetric simulations of vertical displacement events in tokamaks: A benchmark of M3D-C1, NIMROD, and JOREK

et al. 2020

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“…which is also called sideways [2][3][4][5][9][10][11][12][13][14][15][16][17]19,21,23,30,31 or lateral 3,18 force. Here, e X is the unit vector along a fixed horizontal direction.…”

Section: Estimates Of the Sideways Forcementioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Evaluations for ITER give worrisome numbers at the level of hundred MN. [12][13][14][15][16][17][18][19][20][21] There are several approaches [2][3][4][5]7,9,17,19,[21][22][23][24] to calculating the instability-induced electromagnetic forces on the vessel components in tokamaks, but some issues remain unresolved. 13,20 One of them was recently raised in Refs.…”

Section: Introductionmentioning

confidence: 99%

Analytical model of wall forces produced by kink perturbations in tokamaks

Mironov

Pustovitov

2015

Phys. Plasmas

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Analytical model of the electromagnetic forces produced by kink modes on the tokamak wall [H. R. Strauss et al., Phys. Plasmas 17, 082505 (2010)] is revisited. One of the main conclusions of the mentioned paper is that the largest force occurs at cs w % 1, where c is the kink growth rate and s w is the wall penetration time. In the present study, a similar approach is developed under less restrictive assumptions on the plasma and dynamics of perturbation, and a different result is obtained: the force increases with c and must be maximal at cs w ! 1. Additionally, the dependence of its amplitude on the plasma parameters is clarified. All distinctions and their reasons are explained in detail. The analysis is performed in the cylindrical model incorporating a resistive wall treated without traditional thin-wall constraints and covering therefore a full range in cs w . It is applicable to either locked or rotating modes. Estimates of the sideways force are presented and compared with earlier forecasts. V C 2015 AIP Publishing LLC. [http://dx.

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“…A particular concern for large scale tokamaks such as ITER and DEMO is the rotation of the electromagnetic load asymmetry. This rotation could resonate with the mechanical frequencies of the vessel creating a significant amplification of the vessel forces [2,3]. The destabilization of toroidally asymmetric modes is typically associated with the onset of external MHD modes, which are driven by large edge current densities and a low edge safety factor [4].…”

Section: Introductionmentioning

confidence: 99%

Understanding the reduction of the edge safety factor during hot VDEs and fast edge cooling events

et al. 2020

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In the present work a simple analytical approach is presented in order to clarify the physics behind the edge current density behaviour of a hot plasma entering in contact with a resistive conductor. As it has been observed in recent simulations [1], when a plasma enters in contact with a highly resistive wall, large current densities appear at the edge of the plasma. The model shows that this edge current originates from the plasma response, which attempts to conserve the poloidal magnetic flux (Ψ) when the outer current is being lost. The loss of outer current is caused by the high resistance of the outer current path compared to the plasma core resistance. The resistance of the outer path may be given by plasma contact with a very resistive structure or by a sudden decrease of the outer plasma temperature (e.g. due to a partial thermal quench or due to a cold front penetration caused by massive gas injection). For general plasma geometries and current density profiles the model shows that given a small change of minor radius (δa) the plasma current is conserved to first order (δI p = 0 + O(δa 2 )). This conservation comes from the fact that total inductance remains constant (δL = 0) due to an exact compensation of the change of external inductance with the change of internal inductance (δL ext + δL int = 0). As the total current is conserved and the plasma volume is reduced, the edge safety factor drops according to q a ∝ a 2 /I p . Finally the consistency of the resulting analytical predictions is checked with the help of free-boundary MHD simulations.

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Dynamic response of the ITER tokamak during asymmetric VDEs

Cited by 29 publications

References 1 publication

Axisymmetric simulations of vertical displacement events in tokamaks: A benchmark of M3D-C1, NIMROD, and JOREK

Axisymmetric simulations of vertical displacement events in tokamaks: A benchmark of M3D-C1, NIMROD, and JOREK

Analytical model of wall forces produced by kink perturbations in tokamaks

Understanding the reduction of the edge safety factor during hot VDEs and fast edge cooling events

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