Mechanism for Collective Energy Transfer from Neutral Beam-Injected Ions to Fusion-Born Alpha Particles on Cyclotron Timescales in a Plasma

Dendy, R. O.; Chapman-Oplopoiou, B.; Reman, Bernard; Cook, James William S.

doi:10.1103/physrevlett.130.105102

Cited by 7 publications

(5 citation statements)

References 62 publications

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“…Furthermore, experimental results in TFTR [49], AUG [22,23,25], START [27], LHD [37,39], and KSTAR [18] have been attributed to the MCI [54,56]. Recently, a new collective cyclotron resonant process between fast ions and thermalizing fusion-born alpha particles through MCI is predicted by simulation [55], which would affect the transport of helium ash in fusion plasmas. Besides, compressional Alfvén eigenmode (CAE) is also used to explain the ICE phenomena, which is the CAE cyclotron instability driven by the velocity space anisotropy of super-thermal ions [3,[57][58][59].…”

Section: Introductionmentioning

confidence: 98%

“…The magnetoacoustic cyclotron instability (MCI) theory was developed to explain ICE, which is the resonant excitation of perpendicular fast Alfvén waves with ion Bernstein waves, due to the MCI, driven by the non-Maxwellian energetic ions [43][44][45][46][47][48][49][50][51][52][53][54][55]. An approximately linear relationship between the concentration of fusion-born alpha particles, √ n α /n e , (where n α is the alpha particle density, n e is the electron density), and ICE growth rate was predicted by MCI by theories and simulations [54,56], which explained the results of JET D-T experimental result.…”

Section: Introductionmentioning

confidence: 99%

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Identification of core ion cyclotron instabilities on HL-2A tokamak

Liu,

Tong,

Zou

et al. 2023

Nucl. Fusion

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Instabilities in multiplies of ion cyclotron frequency range are identified and termed as core ion cyclotron emission (ICE) in recent HL-2A neutral beam injection (NBI) heated experiments. Characteristics of the core ICE are presented, including frequency dependence and harmonics features. The detected frequencies are found to agree well with the multiplies of the deuterium cyclotron frequency around the magnetic axis. Additionally, the core ICE exhibits a predominantly compressional property. Observations of distinct spectrum features and individual excitation of each harmonic have demonstrated that the core ICE harmonics are independent multiple modes. Notably, the variation of plasma current is a necessary condition for exciting the 4th harmonic ICE individually. The results suggest that the drive mechanism of core ICE varies between the different frequency ranges.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Identification of core ion cyclotron instabilities on HL-2A tokamak

Liu,

Tong,

Zou

et al. 2023

Nucl. Fusion

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“…25 Molecular dynamics (MD) and first-principles methods can reveal the evolution mechanism from an atomic or even electronic perspective and have become an important research method in this field. 26,27 With the help of MD simulations, Fang et al proposed a modification method called nanometric machining of ion implanted materials (NiIM), which has been demonstrated to effectively improve the machinability of brittle materials such as Si, Ge, and SiC. 6,28,29 In addition, ion implantation has been successfully used for precutting material modification.…”

Section: Introductionmentioning

confidence: 99%

“…It is challenging to directly observe the dynamic process of IBM through experiments because it occurs in the range of picosecond (ps) time scale and nanometer (nm) spatial scale . Molecular dynamics (MD) and first-principles methods can reveal the evolution mechanism from an atomic or even electronic perspective and have become an important research method in this field. , With the help of MD simulations, Fang et al proposed a modification method called nanometric machining of ion implanted materials (NiIM), which has been demonstrated to effectively improve the machinability of brittle materials such as Si, Ge, and SiC. ,, In addition, ion implantation has been successfully used for precutting material modification. , It is evident that NiIM offers a promising approach in using modification to aid subsequent machining.…”

Section: Introductionmentioning

confidence: 99%

Subnanoscale Ion Beam Modification-Assisted Smoothing of Heterostructure Surfaces

Zhang,

Guo,

Jin

et al. 2024

ACS Appl. Mater. Interfaces

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Glass ceramic (GC) is the most promising material for objective lenses for extreme ultraviolet lithography that must meet the subnanometer precision, which is characterized by low values of high spatial frequency surface roughness (HSFR). However, the HSFR of GC is typically degraded during ion beam figuring (IBF). Herein, a developed method for constructing molecular dynamics (MD) models of GC was presented, and the formation mechanisms of surface morphologies were investigated. The results indicated that the generation of the dot-like microstructure was the result of the difference in the erosion rate caused by the difference in the intrinsic properties between ceramic phases (CPs) and glass phases (GPs). Further, the difference in the microstructure of the IBF surface under different beam angles was mainly caused by the difference in the two types of sputtering. Quantum mechanical calculations showed that the presence of interstitial atoms would result in electron rearrangement and that the electron localization can lead to a reduction in CP stability. To obtain a homogeneous surface, the effects of beam parameters on the heterogeneous surface were systematically investigated based on the proposed MD model. Then, a novel ion beam modification (IBM) method was proposed and demonstrated by TEM and GIXRD. The range of ion beam smoothing parameters that could effectively converge the HSFR of the modified surface was determined through numerous experiments. Using the optimized beam parameters, an ultrathin homogeneous modified surface within 3 nm was obtained. The HSFR of GC smoothed by ion beam modification-assisted smoothing (IBMS) dropped from 0.348 to 0.090 nm, a 74% reduction. These research results offer a deeper understanding of the morphology formation mechanisms of the GC surfaces involved in ion beam processing and may point to a new approach for achieving ultrasmooth heterostructure surfaces down to the subnanometer scale.

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“…15,16 In addition, fluctuations in the ion cyclotron frequency range, including ion Bernstein waves, are suggested to exist in the high-wavenumber region. 17 These fluctuations may affect the energy balance in the plasma confinement system [18][19][20] and have local kinetic and global effects in the magnetospheric system, 21,22 through heat transport or wave-particle interactions.…”

mentioning

confidence: 99%

Mass dependency of high-wavenumber turbulence in a linear partially magnetized plasma

Kawachi,

Sasaki,

Nishizawa

et al. 2024

Physics of Plasmas

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We investigated the mass dependency of the high-wavenumber turbulence, which occurs at scales smaller than the ion effective Larmor radius, in a partially magnetized plasma column. In this system, two different types of fluctuations were observed: one exhibiting a coherent discrete spectrum, while the other displaying a broadband continuous spectrum. The phase velocities of both types showed a similar mass dependency, approximately matching the ion sound velocity or electron diamagnetic drift velocity. Additionally, we found that the discrete spectrum has a peak interval frequency comparable to the ion cyclotron frequency, which is consistent with ion cyclotron ranges of fluctuations, including ion Bernstein waves.

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Mechanism for Collective Energy Transfer from Neutral Beam-Injected Ions to Fusion-Born Alpha Particles on Cyclotron Timescales in a Plasma

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Cited by 7 publications

References 62 publications

Identification of core ion cyclotron instabilities on HL-2A tokamak

Identification of core ion cyclotron instabilities on HL-2A tokamak

Subnanoscale Ion Beam Modification-Assisted Smoothing of Heterostructure Surfaces

Mass dependency of high-wavenumber turbulence in a linear partially magnetized plasma

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