A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

Kazakov, Ye. O.; Ongena, J.; Eester, D. Van; Bilato, R.; Dümont, R.; Lerche, E.; Mantsinen, M.; Messiaen, A.

doi:10.1063/1.4928880

Cited by 17 publications

(19 citation statements)

References 41 publications

(86 reference statements)

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“…hydrogen minority in deuterium plasma) by means of an injected RF wave with frequency equal to the cyclotron frequency of the minority ion species. The majority species (one [1] of two components [2,3]) imposes the polarization of the magneto-sonic wave with a sufficient left-hand polarized component to accelerate the minority ions species. The second scenario uses the mode conversion through confluence of the fast wave with a slow wave such as the electrostatic ion Bernstein wave or ion cyclotron wave at the ion-ion hybrid layer in the plasma.…”

Section: Introductionmentioning

confidence: 99%

Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

Ragona

Messiaen

2016

Nucl. Fusion

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For the central heating of a fusion reactor ion cyclotron radio frequency heating (ICRH) is the first choice method as it is able to couple RF power to the ions without density limit. The drawback of this heating method is the problem of excitation of the magneto-sonic wave through the plasma boundary layer from the antenna located along the wall, without exceeding its voltage standoff. The amount of coupling depends on the antenna excitation and the surface admittance at the antenna output due to the plasma profile. The paper deals with the optimization of the antenna excitation by the use of sections of traveling-wave antennas (TWAs) distributed all along the reactor wall between the blanket modules. They are mounted and fed in resonant ring system(s). First, the physics of the coupling of a strap array is studied by simple models and the coupling code ANTITER II. Then, after the study of the basic properties of a TWA section, its feeding problem is solved by hybrids driving them in resonant ring circuit(s). The complete modeling is obtained from the matrices of the TWA sections connected to one of the feeding hybrid(s). The solution is iterated with the coupling code to determine the loading for a reference low-coupling ITER plasma profile. The resulting wave pattern up to the plasma bulk is derived. The proposed system is totally load resilient and allows us to obtain a very selective exciting wave spectrum. A discussion of some practical implementation problems is added.

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Section: Introductionmentioning

confidence: 99%

Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

Ragona

Messiaen

2016

Nucl. Fusion

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“…This is an extension of the three-ion species ICRH technique reported earlier [6][7][8] to convert traditional electron heating scenarios (through mode conversion) to effective ion absorption scenarios. Synergetic ICRH+NBI acceleration of D-NBI ions was also at work in earlier D- 3 He plasmas [13][14][15].…”

Section: Discussionmentioning

confidence: 99%

“…First, by adding a third ion species to the plasma with a different Z/A value than that of the two main ions such that (Z/A) 2 < (Z/A) 3 < (Z/A) 1 . Such 'three-ion' ICRF scenarios have been theoretically developed in [6,7], and later confirmed in dedicated JET and Alcator C-Mod experiments [8]. Typical dispersion curve (hot-plasma approximation) for the fast magnetosonic wave in a mixture plasma, without (blue dotted line) and with a population of fast beam ions (red solid line).…”

Section: Introductionmentioning

confidence: 99%

Synergetic heating of D-NBI ions in the vicinity of the mode conversion layer in H-D plasmas in JET with the ITER like wall.

Ongena¹,

Kazakov²,

Baranov

et al. 2017

EPJ Web Conf.

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Abstract. This paper discusses the extension of the 'three-ion' species ICRF technique for heating mixture plasmas using fast injected NBI ions as resonant 'third' species. In this scenario the ICRF power is absorbed by the fast beam ions in the vicinity of the mode conversion layer where the left-hand polarized RF electric field E + is strongly enhanced. The ions in the beam velocity distribution that have a Doppler-shifted resonance close to the mode conversion layer efficiently absorb RF power and undergo acceleration. We show first experimental observations of ICRF heating of D-NBI ions in H-D plasmas in JET with the ITER-like wall. In agreement with theoretical predictions and numerical modelling, acceleration of the D-NBI ions in this D-(D NBI )-H scenario is confirmed by several fast-ion measurements. An extension of the heating scheme discussed here is acceleration of T-NBI and D-NBI ions in D-T plasmas, offering the potential to further boost the Q-value in future D-T campaigns in JET.

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“…Plasmas in JET and the future tokamak ITER naturally contain a small amount of 9 Be impurities. Since (Z/A) T < (Z/A) 9Be < (Z/A) D , 9 Be ions can efficiently absorb RF power and transfer most of their energy to D and T ions during their collisional slowing-down, a feature particularly attractive for a fusion reactor 10 . As another example of three-ion technique, we mention the observed parasitic off-axis absorption of ICRH power by 7 Li impurities in TFTR D-T plasmas 27 .…”

Section: Efficient Generation Of High-energy Ionsmentioning

confidence: 99%

“…Heating minority ions at higher concentrations is equally possible; plasma mixtures with 1 X ≳ * 1 X are more optimal in this case 10 . The method can also be extended to plasmas containing more than three ion species by adapting slightly the plasma composition.…”

Section: Figure 1 | a New Technique For Fast-ion Generation In Magnetmentioning

confidence: 99%

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

Kazakov¹,

Ongena²,

Wright

et al. 2017

Nature Phys

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We describe a new technique for efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed 'three-ion' scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of this technique on the world-largest plasma magnetic confinement device JET (Joint European Torus, Culham, UK) and the high magnetic field tokamak Alcator C-Mod (MIT, USA). The obtained results demonstrate efficient acceleration of 3 He ions to high energies in dedicated hydrogen-deuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast 3 He ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space plasma environments, in particular, 3 He-rich solar flares.Accepted version of the paper published in Nature Physics (2017) http://dx

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A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

Cited by 17 publications

References 41 publications

Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

Synergetic heating of D-NBI ions in the vicinity of the mode conversion layer in H-D plasmas in JET with the ITER like wall.

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

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