On the physics guidelines for a tokamak DEMO

Zohm, H.; Angioni, C.; Fable, E.; Federici, G.; Gantenbein, G.; Hartmann, Tobias; Lackner, K.; Poli, E.; Porte, L.; Sauter, O.; Tardini, G.; Ward, D.J.; Wischmeier, M.

doi:10.1088/0029-5515/53/7/073019

Cited by 202 publications

(221 citation statements)

References 28 publications

(32 reference statements)

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“…The CD method must be compatible with the environment of the ignited plasma, and its efficiency must be sufficiently high not to compromise the global power balance of the reactor. In the present planning phase of the DEMO reactor [2], it is therefore natural to explore the advantages and limitations of the various options available for non-ohmic CD, taking into account these requirements. In the Ion Cyclotron (IC) range of frequencies radio frequency (RF) power is readily available, and can be used also for auxiliary ion heating during start-up.…”

Section: Introductionmentioning

confidence: 99%

On radio frequency current drive in the ion cyclotron range of frequencies in DEMO and large ignited plasmas

Brambilla

Bilato

2015

Nucl. Fusion

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Abstract. To explore the possibility of efficient Fast Wave current drive in an ignited plasma in the Ion Cyclotron (IC) range of frequency in spite of competition from absorption by ions, we have added to the full-wave toroidal code TORIC a set of subroutines which evaluate absorption by these particles at Ion Cyclotron harmonic resonances, using a realistic "slowing-down" distribution function, and taking into account that their Larmor radius is comparable or even larger than the Fast Wave wavelength. The thermalized population of α-particles is not a serious competitor for power absorption as long as their number density is compatible with maintenance of ignition. By contrast, the energetic slowing down fraction, in spite of its even greater dilution, can absorb from the waves a substantial amount of power at the cyclotron resonance and its harmonics. An extensive exploration both in frequency and in toroidal wavenumbers using the parameters of one of the European versions of DEMO shows that three frequency windows exist in which damping is nevertheless predominantly on the electrons. Designing an antenna capable of shaping the launched spectrum to optimize current drive, however, will not be straightforward. Only in a narrow range when the first IC harmonic of Tritium is deep inside the plasma on the highfield side of the magnetic axis, and that of Deuterium and Helium is still outside on the low-field side, it appears possible to achieve a satisfactory current drive efficiency with a conventional multi-strap antenna, preferentially located in the upper part of the vessel. Exploiting the other two windows at quite low and quite high frequencies is either impossible on first principles, or will demand novel ideas in antenna design.PACS numbers: 52.25 Fi, 52.25 Ya, 52.55 Fa

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Section: Introductionmentioning

confidence: 99%

On radio frequency current drive in the ion cyclotron range of frequencies in DEMO and large ignited plasmas

Brambilla

Bilato

2015

Nucl. Fusion

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“…In this section we will obtain, by numerical simulations, the LH-driven current density considering the parameters of plasma, magnetic equilibrium and antenna relevant for DEMO [12,14] and ITER [13,15]. DEMO can operate in pulsed and Steady State regime both characterized by flat or peaked kinetic profiles.…”

Section: Numerical Results For Demo and Itermentioning

confidence: 99%

Quasi-linear modeling of lower hybrid current drive in ITER and DEMO

Cardinali¹,

Cesario²,

Panaccione³

et al. 2015

AIP Conference Proceedings

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Abstract. First pass absorption of the Lower Hybrid waves in thermonuclear devices like ITER and DEMO is modeled by coupling the ray tracing equations with the quasi-linear evolution of the electron distribution function in 2D velocity space. As usually assumed, the Lower Hybrid Current Drive is not effective in a plasma of a tokamak fusion reactor, owing to the accessibility condition which, depending on the density, restricts the parallel wavenumber to values greater than n ||crit and, at the same time, to the high electron temperature that would enhance the wave absorption and then restricts the RF power deposition to the very periphery of the plasma column (near the separatrix). In this work, by extensively using the "ray star " code, a parametric study of the propagation and absorption of the LH wave as function of the coupled wave spectrum (as its width, and peak value), has been performed very accurately. Such a careful investigation aims at controlling the power deposition layer possibly in the external half radius of the plasma, thus providing a valuable aid to the solution of how to control the plasma current profile in a toroidal magnetic configuration, and how to help the suppression of MHD mode that can develop in the outer part of the plasma. This analysis is useful not only for exploring the possibility of profile control of a pulsed operation reactor as well as the tearing mode stabilization, but also in order to reconsider the feasibility of steady state regime for DEMO.

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“…Negative ion sources [1,2,3] are a fundamental component of Neutral Beam Injectors (NBI) [4,5,6,7,8,9], which contribute most of the additional plasma heating and current drive to the International Tokamak Experimental Reactor (ITER) project and which need to be strongly optimized in the perspective of the more demanding DEMO reactor [10]. A relatively compact radiofrequency (rf) ion source, named NIO1 (Negative Ion Optimization phase 1) is being developed and tested in Padua, Italy, in collaboration bewteen Consorzio RFX and INFN [11], in the framework of the accompanying activities in support to the ITER NBI test facility and to the Megavolt ITer Injector Concept Advancement (MITICA) [8], to provide a test bench for source optimizations.…”

Section: Introductionmentioning

confidence: 99%