Fusion's False Dawn

Moyer, M.

doi:10.1038/scientificamerican0310-50

Cited by 18 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Science [60], Nature [61,62] and more recently in Scientific American [63], it has been shown that turbulence could negatively affect ITER operation by worsening energy confinement through increased heat and particle transport. Hence, it is important to assess whether this mechanism for ITG turbulence stabilization by fusion-born αs could also work in the foreseen ITER plasmas.…”

Section: Predictions On Itg Stabilization By Alpha Particles For Itermentioning

confidence: 99%

A phenomenological explanation for the anomalous ion heating observed in the JET alpha-heating experiment of 1997

Testa¹,

Albergante²

2012

Nucl. Fusion

View full text Add to dashboard Cite

In the so-called 'alpha-heating' experiment performed on the JET tokamak during the deuterium-tritium campaign of 1997, the ion temperature was found to be far exceeding (both in absolute value and in its rise time) the level that could have been expected from direct collisional heating by the fusion-born alpha particles themselves and energy equipartition with the electrons. To date, no explanation has been put forward for this long standing puzzle, despite much work having been performed on this subject in the early 2000s.Two analysis methods that have recently become available have been employed to re-analyse these observations of an anomalous ion heating. First, an algorithm based on the sparse representation of signals has been used to analyse magnetic, reflectometry and electron-cyclotron emission measurements of the turbulence spectra in the drift-wave range of frequencies. This analysis has then been complemented with turbulence simulations performed with the GENE code.We find, both experimentally and in the simulations, that the presence of a minority, but sufficiently large, population of fusion-born alpha particles that have not yet fully thermalized stabilizes the turbulence in the ion-drift direction, but practically does not affect the turbulence in the electron-drift direction. We link such stabilization of the ion-drift-wave turbulence to the increase in the ion temperature above the level achieved in similar discharges that did not have (at all or enough) alpha particles. When the fusion-born alpha particles have fully thermalized, the turbulence spectrum in the ion-drift direction reappears at somewhat larger amplitudes, which we link to the ensuing reduction in the ion temperature. This phenomenological dynamics fully corresponds to the actual experimental observations. By taking into account an effect of the alpha particles that had not been previously considered, our new analysis finally presents a phenomenological explanation for the so-far-unexplained anomalous ion heating observed in the JET alpha-heating experiment of 1997.Through the formulation of an empirical criterion for ion-drift-wave turbulence stabilization by fusion-born alpha particles, we also show why similar observations were not made in the other deuterium-tritium experiments run so far in JET and TFTR. This allows assessing the operational domain for this stabilization mechanism for ion-drift-wave turbulence in future burning plasma experiments such as ITER, which may open a new path towards the sustainment of a high energy gain in such forthcoming devices.

show abstract

Section: Predictions On Itg Stabilization By Alpha Particles For Itermentioning

confidence: 99%

A phenomenological explanation for the anomalous ion heating observed in the JET alpha-heating experiment of 1997

Testa¹,

Albergante²

2012

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…To this aim, we start from the ansatz that there is a direct link between electron and ion-drift-wave micro-instabilities, such as Trapped Electron Modes (TEM), Electron and Ion Temperature Gradient (ETG and ITG, respectively) turbulence, and the temporal evolution of the thermal-electron and -ion temperatures through modifications to the electron and ion diffusivity and thermal conductivity [17]. In [18][19][20] and more recently in [21], it has been shown that turbulence could negatively affect ITER operation by worsening energy confinement through increased heat and particle transport. Hence, it is important to assess whether this 1997 JET DTE1 data indicate that αs can contribute to turbulence suppression and the ensuing reduction in thermal-ion heat transport.…”

Section: -P2mentioning

confidence: 99%

Evidence for a new path to the self-sustainment of thermonuclear fusion in magnetically confined plasmas

Testa¹,

Albergante²

2012

EPL

View full text Add to dashboard Cite

In this work we provide the first explanation for observations made in 1997 on the Joint European Torus of unexpected ion heating with fusion-born alpha particles occurring over time scales much shorter than those theoretically foreseen. We demonstrate that non-thermal alpha particles above a critical concentration stabilize ion-drift-wave turbulence, therefore significantly reducing one of the main energy loss channels for thermal ions. As such ion heating occurs over times scales much shorter than those classically predicted, this mechanism opens new prospects on additional paths for the self-sustainment of thermonuclear fusion reactions in magnetically confined plasmas.

show abstract

“…The 4π coverage provides an enhanced tritium breeding ratio of 1.6 to 1.8 [6]. The neutron multiplication factor results from the Pb(n,2n) reaction and also from the 7 Li + n → 4 He + 3 H + n reaction as diagrammed by Moyer [7]. The challenge with a thick Pb-17Li liner is likely to be too much tritium production.…”

Section: Fusion By Acoustic Implosionmentioning

confidence: 97%

Acoustically driven Magnetized Target Fusion

Laberge

Howard

Richardson

et al. 2013

2013 IEEE 25th Symposium on Fusion Engineering (SOFE)

View full text Add to dashboard Cite

General Fusion is a 65-employee private company developing fusion energy with $40M of capital to date. This report will describe General Fusion's design for an acoustically driven Magnetized Target Fusion (MTF) reactor concept. The advantages of this particular MTF scheme will be discussed. Our experimental and numerical work and results so far will be presented, as well as plans for future development

show abstract

Fusion's False Dawn

Cited by 18 publications

References 0 publications

A phenomenological explanation for the anomalous ion heating observed in the JET alpha-heating experiment of 1997

A phenomenological explanation for the anomalous ion heating observed in the JET alpha-heating experiment of 1997

Evidence for a new path to the self-sustainment of thermonuclear fusion in magnetically confined plasmas

Acoustically driven Magnetized Target Fusion

Contact Info

Product

Resources

About