Achievements of Actively Controlled Divertor Detachment Compatible with Sustained High Confinement Core in DIII-D and EAST

Abstract The compatibility of efficient divertor detachment with high-performance core plasma is vital to the development of magnetically controlled fusion energy. The joint research on the EAST and DIII-D tokamaks demonstrates successful integration of divertor detachment with excellent core plasma confinement quality, a milestone towards solving the critical Plasma-wall-interaction (PWI) issue and core-edge integration for ITER and future reactors. In EAST, actively controlled partial detachment with Tet,div ~ 5 eV around the strike point and H98 > 1 in different H-mode scenarios including the high βP H-mode scenario have been achieved with ITER-like tungsten divertor, by optimizing the detachment access condition and performing detailed experiments for core-edge integration. For active long pulse detachment feedback control, a 30s H-mode operation with detachment-control duration being 25s has been successfully achieved in EAST. DIII-D has achieved actively controlled fully detached divertor with low plasma electron temperature (Tet,div ≤ 5 eV across the entire divertor target) and low particle flux (degree of detachment, DoD >3), simultaneously with very high core performance (βN ~3, βP >2 and H98~1.5) in the high βP scenario being developed for ITER and future reactors. The high-βP high confinement scenario is characterized by an internal transport barrier (ITB) at large radius and a weak edge transport barrier (ETB, or pedestal), which are synergistically self-organized. Both the high-βP scenario and impurity seeding facilitate divertor detachment. The detachment access leads to the reduction of ETB, which facilitates the development of an even stronger ITB at large radius in the high βP scenario. Thus, this strong large radius ITB enables the core confinement improvement during detachment. These significant joint DIII-D and EAST advances on the compatibility of high confinement core and detached divertor show a great potential for achieving a high-performance core plasma suitable for long pulse operation of fusion reactors with controllable steady-state PWIs.

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Integration of full divertor detachment with improved core confinement for tokamak fusion plasmas

Nature Communications ◽

10.1038/s41467-021-21645-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

L. Wang ◽

H. Q. Wang ◽

S. Ding ◽

A. M. Garofalo ◽

X. Z. Gong ◽

...

Keyword(s):

Steady State ◽

High Performance ◽

Confinement Loss ◽

Fusion Plasmas ◽

Large Radius ◽

Transport Barrier ◽

Self Organized ◽

Steady State Operation ◽

Core Plasma ◽

Promising Solution

AbstractDivertor detachment offers a promising solution to the challenge of plasma-wall interactions for steady-state operation of fusion reactors. Here, we demonstrate the excellent compatibility of actively controlled full divertor detachment with a high-performance (βN ~ 3, H98 ~ 1.5) core plasma, using high-βp (poloidal beta, βp > 2) scenario characterized by a sustained core internal transport barrier (ITB) and a modest edge transport barrier (ETB) in DIII-D tokamak. The high-βp high-confinement scenario facilitates divertor detachment which, in turn, promotes the development of an even stronger ITB at large radius with a weaker ETB. This self-organized synergy between ITB and ETB, leads to a net gain in energy confinement, in contrast to the net confinement loss caused by divertor detachment in standard H-modes. These results show the potential of integrating excellent core plasma performance with an efficient divertor solution, an essential step towards steady-state operation of reactor-grade plasmas.

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High performance reversed shear plasmas with a large radius transport barrier in JT-60U

Nuclear Fusion ◽

10.1088/0029-5515/38/2/305 ◽

1998 ◽

Vol 38 (2) ◽

pp. 207-221 ◽

Cited By ~ 68

Author(s):

T Fujita ◽

T Hatae ◽

T Oikawa ◽

S Takeji ◽

H Shirai ◽

...

Keyword(s):

High Performance ◽

Large Radius ◽

Transport Barrier ◽

Reversed Shear

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AFX Zeolite for Use as a Support of NH3-SCR Catalyst Mining through AICE Joint Research Project of Industries–Academia–Academia

Catalysts ◽

10.3390/catal11020163 ◽

2021 ◽

Vol 11 (2) ◽

pp. 163

Author(s):

Masaru Ogura ◽

Yumiko Shimada ◽

Takeshi Ohnishi ◽

Naoto Nakazawa ◽

Yoshihiro Kubota ◽

...

Keyword(s):

High Performance ◽

Ionic Species ◽

Research Project ◽

Joint Research ◽

Structure Directing Agent ◽

Scr Catalyst ◽

Organic Structure ◽

Nh3 Scr ◽

Joint Research Project ◽

The One

This paper introduces a joint industries–academia–academia research project started by researchers in several automobile companies and universities working on a single theme. Our first target was to find a zeolite for NH3-SCR, that is, zeolite mining. Zeolite AFX, having the same topology of SSZ-16, was found to be the one of the zeolites. SSZ-16 can be synthesized by using an organic structure-directing agent such as 1,1′-tetramethylenebis(1-azonia-4-azabicyclo[2.2.2]octane; Dab-4, resulting in the formation of Al-rich SSZ-16 with Si/Al below five. We found that AFX crystallized by use of N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium ion, called TEBOP in this study, had the same analog as SSZ-16 having Si/Al around six and a smaller particle size than SSZ-16. The AFX demonstrated a high performance for NH3-SCR as the zeolitic support to load a large number of divalent Cu ionic species with high hydrothermal stability.

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Effects of diadenosine polyphosphates and seminal fluid vesicles on rabbit sperm cells

Reproduction ◽

10.1530/rep.0.1250827 ◽

2003 ◽

pp. 827-835 ◽

Cited By ~ 14

Author(s):

A Minelli ◽

L Liguori ◽

I Bellezza ◽

T Renieri ◽

C Castellini

Keyword(s):

High Performance ◽

Acrosome Reaction ◽

Seminal Fluid ◽

Membrane Vesicles ◽

Fluorescein Isothiocyanate ◽

Plasma Electron ◽

Sperm Cells ◽

Experimental Conditions ◽

Diadenosine Polyphosphates ◽

Rabbit Spermatozoa

Membrane vesicles were isolated from rabbit seminal plasma. Electron microscopy analyses showed the presence of numerous small, round vesicles with a diameter of about 70 nm. Determination of enzyme activities was carried out by high performance liquid chromatography and showed that the vesicles can degrade the diadenosine polyphosphates (ApnA), Ap3A and Ap4A and ATP and ADP, but not AMP. Studies of the degradation of diadenosine compounds by the vesicles present in seminal fluid showed an increasing production of AMP as the by-product and a time-dependent generation of dephosphorylated products consistent with the presence of ecto-ATP diphosphophosphatase (ecto-apyrase). In the presence of rabbit spermatozoa, AMP did not accumulate because 5'nucleotidase and adenosine deaminase, present at the surface of sperm cells, transformed AMP into adenosine and inosine. The effects of seminal fluid vesicles and diadenosine compounds on the acquisition of fertilizing capacity by rabbit spermatozoa were evaluated by Pisum sativum agglutinin fluorescein isothiocyanate conjugated staining. The results obtained with uncapacitated spermatozoa showed that the capacitating effector BSA could be substituted efficiently by the addition of diadenosine compounds and vesicles previously incubated for 2 h to the capacitative medium. Under these experimental conditions, the spontaneous acrosome reaction rate was not increased. Capacitated rabbit spermatozoa did not undergo acrosome reaction when l-alpha-lysophosphatidylcholine was substituted by diadenosine compounds previously incubated with vesicles. In conclusion, this study has shown that rabbit seminal fluid vesicles can degrade diadenosine compounds to AMP and that the addition of the vesicles and diadenosine compounds to uncapacitated rabbit spermatozoa favours the acquisition of the fertilizing capacity.

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Confinement improvement during detached phase with RMP application in deuterium plasmas of LHD

Nuclear Fusion ◽

10.1088/1741-4326/ac42f3 ◽

2021 ◽

Author(s):

Masahiro Kobayashi ◽

Ryosuke Seki ◽

Yuki Hayashi ◽

Tetsutarou Oishi ◽

Kanji Tanaka ◽

...

Keyword(s):

Heat Load ◽

Field Application ◽

Edge Plasma ◽

Magnetic Fluctuations ◽

Transport Barrier ◽

Radiation Level ◽

Hydrogen Plasmas ◽

Core Plasma ◽

Load Increase ◽

Stochastic Layer

Abstract In order to explore compatibility of good core plasma performance with divertor heat load mitigation, interaction between cold edge plasma and core plasma transport including edge transport barrier (ETB) has been analysed in the divertor detachment discharges of deuterium plasmas in LHD with RMP (resonant magnetic perturbation) field application. The RMP application introduces widened edge stochastic layer and sharp boundary in the magnetic field structure between the confinement region and the edge stochastic layer. The widened edge stochastic layer enhances impurity radiation and provides stable detachment operation as compared with the case without RMP. It is found that ETB is formed at the confinement boundary at the onset of detachment transition. However, as the detachment deepens resistive pressure gradient driven MHD mode is excited, which degrade the ETB. At the same time, however, the core transport decreases to keep global plasma stored energy (Wp) unchanged, showing clearly core-edge coupling. After gradual increase of density fluctuation during the MHD activity, spontaneous increase of Wp and recovery of ETB are observed while the detachment is maintained. Then the coherent MHD mode ceases and ELM like bursts appear. In the improved mode, the impurity decontamination occurs, and the divertor heat load increase slightly. Key controlling physics in the interplay between core and cold edge plasma is discussed. Comparison between deuterium and hydrogen plasmas show that the hydrogen plasmas exhibit similar features as the deuterium ones in terms of density and magnetic fluctuations, impurity decontamination toward higher confinement etc. But most of the features are modest in the hydrogen plasmas and thus no clear confinement mode transition with clear ETB formation is defined. Better global confinement is obtained in the deuterium plasmas than the hydrogen ones at higher radiation level.

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