Investigation of NO removal using a pulse-assisted RF discharge

Wang, Qi; Wang, Yanhui; Wang, Haochen; Wang, Zhanhui; Ding, Hongbin

doi:10.1088/2058-6272/aa607b

Cited by 7 publications

(7 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To increase the plasma-wetted area [19], the chamfer shaping with 1 mm cutting in both toroidal and radial directions has been used for both left and right corners of the tungsten monoblocks, as shown in figure 1(c). This can decrease the maximum temperature to some extent with the misalignment below the limit value of about 0.94 mm [20]. However, the maximum misalignment between adjacent cassette modules could reach up to a maximum of 3 mm according to the actual measurements after assembly.…”

Section: Tungsten Divertor In Eastmentioning

confidence: 99%

Characterization of the in situ leading-edge-induced melting on the ITER-like tungsten divertor in EAST

Zhu

Ding

et al. 2019

Nucl. Fusion

View full text Add to dashboard Cite

Understanding tungsten melting behavior and its influence on plasma operation is one of the main concerns for ITER, which will be operated with a full tungsten divertor. Similar to ITER, actively cooled tungsten cassette modules have been successfully installed for the upper divertor in EAST for a stronger heat exhaust ability. However, an unexpected in situ tungsten melting phenomenon has been observed around the strike point area on both the inner and outer targets during recent EAST plasma campaigns. It was identified that such tungsten melting was caused by the leading edges, which leads to much high heat load on the protruded edges of the cassette modules. All tungsten melting occurred only at the edges of the cassette modules where larger misalignment up to millimeter scale was formed. The melted layer, which was mainly driven by the electromagnetic force, was moved either up or down under different conditions. Only a few bridge connections along the vertical direction could be formed. Such tungsten melting ejected a large number of droplets into the core plasma, and resulted in a sharp increase of tungsten impurity and power radiation and could eventually lead to disruptions. With droplet ejection and melted layer removal, the melted corner seems to form a moderate chamfer structure and thus may mitigate the temperature rise. Under current operation conditions, EAST can tolerate such melting to some extent. Several solutions to help avoid this kind of melting have been proposed according to the thermal analysis for future EAST operations.

show abstract

Section: Tungsten Divertor In Eastmentioning

confidence: 99%

Characterization of the in situ leading-edge-induced melting on the ITER-like tungsten divertor in EAST

Zhu

Ding

et al. 2019

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…In the hybrid fluid model, the plasma is assumed to be the fluid. The fluid governing equations for LRIT-40 are ion continuity equation [24] u where ν in is the elastic scattering frequency of ion and neutral atom, α represents the different species of ions, ν θ is the angular average electron current velocity that driven by RF field. The boundary conditions for solving the electric potential are divided into two parts: plasma discharge electric potential and the ion optics grids system electric potential.…”

Section: Inductively Coupled Discharge Fluid Modelmentioning

confidence: 99%

Numerical research of a 2D axial symmetry hybrid model for the radio-frequency ion thruster

Wu¹,

Sun²,

Zuo³

et al. 2018

Plasma Sci. Technol.

View full text Add to dashboard Cite

Since the high efficiency discharge is critical to the radio-frequency ion thruster (RIT), a 2D axial symmetry hybrid model has been developed to study the plasma evolution of RIT. The fluid method and the drift energy correction of the electron energy distribution function (EEDF) are applied to the analysis of the RIT discharge. In the meantime, the PIC-MCC method is used to investigate the ion beam current extraction character for the plasma plume region. The beam current simulation results, with the hybrid model, agree well with the experimental results, and the error is lower than 11%, which shows the validity of the model. The further study shows there is an optimal ratio for the radio-frequency (RF) power and the beam current extraction power under the fixed RIT configuration. And the beam extraction efficiency will decrease when the discharge efficiency beyond a certain threshold (about 87 W). As the input parameters of the hybrid model are all the design values, it can be directly used to the optimum design for other kinds of RITs and radio-frequency ion sources.

show abstract

“…The ECH switch-off also causes an increased inward particle pinch at electron scales, as displayed in figure 16, whose wavelength integral accounts for about 25% of the outward particle flux generated by ion scale fluctuations. Such pinch might be connected to the well known ECH density pump-out effect [24], whose experimental characterization is the subject of active research [25,26] due to its importance in determining the density radial profile in future machines. Previous work identified the cause of the pump-out in the switch of the direction of propagation of the dominant ion-scale instability, which would result in a modification of density peaking via a reversal of the direction of the thermo-diffusive pinch [27]; that work was based on detailed gyrokinetic analysis of plasmas in two different stationary phases: before and after the modification of the density peaking was observed.…”

Section: Gyrokinetic Modelingmentioning

confidence: 99%

The effect of electron cyclotron heating on density fluctuations at ion and electron scales in ITER baseline scenario discharges on the DIII-D tokamak

et al. 2017

View full text Add to dashboard Cite

Experiments simulating the ITER baseline scenario on the DIII-D tokamak show that torque-free pure electron heating, when coupled to plasmas subject to a net co-current beam torque, affects density fluctuations at electron scales on a sub-confinement time scale, whereas fluctuations at ion scales change only after profiles have evolved to a new stationary state. Modifications to the density fluctuations measured by the phase contrast imaging diagnostic (PCI) are assessed by analyzing the time evolution following the switch-off of electron cyclotron heating (ECH), thus going from mixed beam/ECH to pure neutral beam heating at fixed . Within 20 ms after turning off ECH, the intensity of fluctuations is observed to increase at frequencies higher than 200 kHz; in contrast, fluctuations at lower frequency are seen to decrease in intensity on a longer time scale, after other equilibrium quantities have evolved. Non-linear gyro-kinetic modeling at ion and electron scales scales suggest that, while the low frequency response of the diagnostic is consistent with the dominant ITG modes being weakened by the slow-time increase in flow shear, the high frequency response is due to prompt changes to the electron temperature profile that enhance electron modes and generate a larger heat flux and an inward particle pinch. These results suggest that electron heated regimes in ITER will feature multi-scale fluctuations that might affect fusion performance via modifications to profiles.

show abstract

Investigation of NO removal using a pulse-assisted RF discharge

Cited by 7 publications

References 25 publications

Characterization of the in situ leading-edge-induced melting on the ITER-like tungsten divertor in EAST

Characterization of the in situ leading-edge-induced melting on the ITER-like tungsten divertor in EAST

Numerical research of a 2D axial symmetry hybrid model for the radio-frequency ion thruster

The effect of electron cyclotron heating on density fluctuations at ion and electron scales in ITER baseline scenario discharges on the DIII-D tokamak

Contact Info

Product

Resources

About