Dr
paolo zanca
(consorzio rfx)
25/10/2018, 08:30
Poster
A density limit (DL), causing either a disruption or a soft termination of the discharge, is generally found in magnetic confinement fusion devices. Some empirical scaling laws have been proposed to order the maximum achievable densities. The Sudo density, n_Sudo∝(P〖 B〗_ϕ )^0.5 [1], with P the heating power, is generally applied to the stellarator. The Greenwald density, n_G=I_p⁄((π a^2 ) )...
Mrs
Deepti sharma
(Institute for Plasma Research, Gandhingar, India)
25/10/2018, 08:30
Poster
The ADITYA tokamak device is used to produce circular plasma for few
hundreds of milli-seconds. The edge physics study in this device is led to
significant contributions. The upgradation of this device is focused to
address issues relevant to heat removal capability at the plasma edge. This
requires to construct plasma equilibrium with divertor configuration. In this regard, additional...
Dr
G.Z. Hao
(Southwestern Institute of Physics, Chengdu 610041, China)
25/10/2018, 08:30
Poster
There is a longstanding issue on the physical nature of a low frequency (<50 kHz) MHD instability observed at the early phase of the discharges of a spherical tokamak (ST) - the National Spherical Torus Experiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557). This work provides evidence that low frequency modes in spherical tokamaks are often driven by the rapid plasma flow. The centrifugal...
Dr
Wenzhe Mao
(University of Science and Technology of China)
25/10/2018, 08:30
Poster
Electrostatic turbulence is the main constrain of confinement improvement on low $\beta$ toroidal magnetic confinement devices. With the development of high $\beta$ operation scenario, electromagnetic turbulence is expected to become important for development of resistive tearing mode and resistive wall mode. The characteristics of electromagnetic turbulence on KTX are studied in low current...
Dr
Gunyoung Park
(National Fusion Research Institute)
25/10/2018, 08:30
Poster
Control of the edge localized modes (ELMs) is one of the most critical issues for a ITER and the future tokamak fusion reactors. In order to develop a *predictive* model of the access to ELM-crash suppressed states, it is essential to understand first the underlying physics mechanism of ELM-crash-suppression. This paper reports comparative simulation results for particular KSTAR experimental...
Prof.
YI LIU
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
Advanced tokamak scenario with central q close to 1 has been achieved on HL-2A tokamak. An ITB has been observed during the nonlinear evolution of a saturated long-lived internal mode (LLM) or fishbone activities in HL-2A discharges as the q-profile formed a very broad low-shear region with qmin ~ 1. Such steep ion temperature-gradient zone locates around r/a=0.5-0.6 with Ti>Te. The observed...
Mr
Leonid Khimchenko
(ITERRu)
25/10/2018, 08:30
Poster
Extreme high heat loads, both during steady state and transient events, expected on the tungsten divertor plates of the ITER facility, undertaken at Cadarache, France. In this paper nonambipolar plasma flow toward the surface, due to arcs and sparks, was investigated as mechanism of power exhaust, leading to enhanced heating of plasma facing materials (PFMs) at a very high heat load. This...
Dr
Yipo Zhang
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
Effect of the pedestal deposited impurity on the edge-localized mode (ELM) behaviour has been observed and intensively investigated in the HL-2A tokamak. Impurities have been externally seeded by a newly developed laser blow-off (LBO) system. Both mitigation and suppression of ELMs have been realized by LBO-seeded impurity. Measurements have shown that the LBO-seeded impurity particles are...
Dr
Juhyung Kim
(National Fusion Research Institute)
25/10/2018, 08:30
Poster
Edge localized modes (ELMs) are quasi-periodic relaxation of tokamak pedestal, releasing large heat flux on divertor places. Although ELMs are thought to be triggered by MHD peeling-ballooning instability, the nonlinear relaxation process is not fully understood.
MHD filaments can carry out heat to scrape of layers (SOL) without reconnection [1].
On the contrary, a magnetic topology change...
Dr
Alexander Melnikov
(NRC 'Kurchatov Institute')
25/10/2018, 08:30
Poster
New experimental observations and theoretical description of the plasma potential and radial electric field Er formation in the T-10 tokamak are presented. The potential was measured by heavy ion beam probe (HIBP) diagnostic from the plasma core to edge with high spatial (<1 cm) and temporal (1 mus) resolution, and by Langmuir probe (LP) at the edge. Low-density OH deuterium plasma...
Ms
Y Patil
(Institute For Plasma Research)
25/10/2018, 08:30
Poster
The APPEL (Applied Plasma Physics Experiments in Linear Device) is an experimental system designed to carry out basic plasma physics experiments as well as serve as a test-bed for experimenting various plasma facings components interaction with strongly magnetized plasma. This versatile device consists of 16 large electromagnet coils weighing up to 700 kg each, which are made from CTC...
Mr
Peiwan Shi
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
The stationary and nonstationary toroidal Alfvén eigenmodes (TAE) driven by energetic-ion have been observed on HL-2A. The mode frequencies are about 90-200 kHz and toroidal mode numbers for the most unstable mode are n=1–3. The radial structure of the mode with n=2 confirmed by the Alfvén Mode Code (AMC) make up of poloidal harmonic m=2 and m=3, which is a typical feature of TAE. The...
Allan Reiman
(Princeton Plasma Physics Lab)
25/10/2018, 08:30
Poster
A small magnetic island has only a small effect on the ambient pressure gradient, so that the pressure is not constant on the flux surfaces in and near the island. The length scale determining which islands may be regarded as “small” in this context is determined by the ratio of perpendicular to parallel transport. We numerically explore the effect of such a small island on the MHD equilibrium...
Prof.
Xianming SONG
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
HL-2M tokamak is now under construction in China as a modification to the HL-2A facility, with nominal parameters as follows: Ip=1.5-3.0MA, B=2.2T, major radius= 1.78m, minor radius=0.65m, elongation =1.6-1.8, triangularity >0.5. It is a real challenge to build a new machine in fusion community, HL-2M suffers from a long delay for the first plasma. In order to fulfil the requirement of...
Dr
Toseo Moritaka
(Institue for Fusion Science)
25/10/2018, 08:30
Poster
We investigate radial electric field structure in Large Helical Device and its impact on high-energy particle loss at the material wall. We employ global gyrokinetic particle-in-cell code for whole-device simulation, X-point Gyrokinetic Code (XGC), which is currently being extended to non-axisymmetric geometries. The whole-device modeling of fusion plasma is needed to understand edge plasma...
Dr
Robert Hager
(Princeton Plasma Physics Laboratory)
25/10/2018, 08:30
Poster
The gyrokinetic neoclassical particle-in-cell code XGCa coupled to the MHD code M3D-C1 is applied to study the particle and heat flux caused by external 3D magnetic perturbations in a DIII-D H-mode plasma. Despite the existence of KAM surfaces in the pedestal, our simulations, which so far are limited to the 0.5 to 1 ms directly after the RMP field is switched on, show the beginning of density...
Mr
Maxim Nurgaliev
(National Research Centre "Kurchatov Institute")
25/10/2018, 08:30
Poster
Investigation of ion heat conductivity in plasma with ECR-heating and suppressed saw-teeth and modes $(m,n)=(1,1)$ and $(2,1)$ is carried out. Off-axis heating (localization radius is $\rho=r/a \approx0.5$) and combined heating (on-axis ECRH together with off-axis) are considered. It is shown for the ohmic stage that ion heat conductivity is on a neoclassical level in the central zone $\rho...
Dr
Masahiko Sato
(National Institute for Fusion Science)
25/10/2018, 08:30
Poster
For the high beta plasmas in the inward shifted Large Helical Device (LHD) configurations, the plasma peripheral region is theoretically MHD unstable region since there is always a magnetic hill in the plasma peripheral region. However, high beta plasmas with about 5% of the volume averaged beta value are stably obtained in the LHD experiments. This implies that the nonlinear saturation level...
Min Jiang
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
Magnetic islands formed in magnetically confined plasmas have significant influence on plasma profiles and cross-field transport, and can even cause plasma disruption [1,2]. However, observations of internal transport barriers near the rational magnetic surface suggest the importance of magnetic islands in plasma confinement via increase of flow shear at the island boundary [3,4]. In recent...
Linjin Zheng
(University of Texas at Austin)
25/10/2018, 08:30
Poster
Recently, discharges with negative triangularity were created in the DIII-D tokamak. These discharges exhibited the H-mode-level confinement features with L-mode-like edge behavior without ELMs (M.E. Austin et al., Bull. Am. Phys. Soc. vol. 62 (2017)). This led us to extensively examine the MHD stability of negative triangularity tokamaks. Using the numerically reconstructed experimental...
Dr
Shizuo Inoue
(QST)
25/10/2018, 08:30
Poster
The interaction of a locked tearing mode with a non-axisymmetric control field is found to be in good qualitative agreement with predictions of a nonlinear resistive MHD model [1]. Locked tearing mode islands often lead to disruptions in tokamaks. However, experiments have shown that unlocking and rotation of the island by a rotating control field (CF) can postpone or prevent a disruption [2]....
Dr
Xiaoquan JI
(Southwestern Institute of Physics, Chengdu 610041 China)
25/10/2018, 08:30
Poster
In HL-2A low rotation and relatively low density plasmas, the critical threshold of the intrinsic error field penetration will be decreasing. And the multi-helicity islands can be seeded by the non-axisymmetric error field penetration, and lead to the change of rotation profile, enhanced transport or even disruption. Sheared flow arising from momentum injection can suppressed the coupled...
Dr
FENG LIU
(Université Côte d’Azur)
25/10/2018, 08:30
Poster
Both nonlinear simulations and experiments of DIII-D QH-mode plasmas show that E×B rotation plays an essential role for obtaining the QH-mode. However, the mechanism for the QH-mode onset and its saturation, the influence of other rotation flows such as neoclassical flow, diamagnetic flow as well as the influence of resistive wall still remains unclear due to the complexity of the physics of...
Dr
Daniel López-Bruna
(EsLNF)
25/10/2018, 08:30
Poster
The relaxation of the constraint of periodicity imposed by the external confining magnetic field coils in a nominally 4-field period Helias Advanced Stellarator configuration produces weak periodicity-breaking deformations of the plasma. The corrugations are driven by the interaction of the pressure gradient with the magnetic field line curvature and correspond to saturated ideal...
Prof.
Sibylle Günter
(Max-Planck-Institut für Plasmaphysik)
25/10/2018, 08:30
Poster
Neoclassical tearing modes (NTMs) can degrade plasma confinement or even lead to disruptions in existing tokamak discharges. To understand their triggering mechanism by sawtooth crashes and the effect of error fields or externally applied resonant magnetic perturbations (RMPs) on their onset remain to be important for ITER or a fusion power plant. In this paper these two issues are studied...
Mr
Rupak Mukherjee
(Institute for Plasma Research)
25/10/2018, 08:30
Poster
Rupak Mukherjee, Rajaraman Ganesh
Institute for Plasma Research, HBNI, Gandhinagar, Gujarat, India, 382428.
ganesh@ipr.res.in
Since the advent of Taylor-Woltjer theory [1,2], it has been widely believed that situations with perfectly conducting boundaries and near ideal conditions, the final state of MHD system would be force-free Taylor-Woltjer states defined as curl B = alpha B with...
Dmitriy Ryzhakov
(RuKurchatov)
25/10/2018, 08:30
Poster
One of the main goals of researching global plasma disruptions is to find a way to prevent the formation of runaway electron beams, after the plasma current disruption. A possible way to solve this problem is to generation of strong MHD perturbation during current decay. The experimental study of density limit disruption on tokamak T-10, for study dependency a duration of plasma current decay...
Dr
Jun Cheng
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
Streamer, as well as zonal flow is a very challenging subject since it is expected to have significant effects on confinement in high temperature plasmas. Theoretical simulation predicts that streamers originate from the nonlinear development of turbulence driven by electron and ion temperature gradient. In experiments, few works have reported the streamer observation only up to now, and...
Prof.
Yuhong Xu
(Southwest Jiaotong University)
25/10/2018, 08:30
Poster
The Chinese First Quasi-axisymmetric Stellarator (CFQS) is a joint project of international collaboration. It is designed and fabricated by Southwest Jiaotong University (SWJTU) in China and National Institute for Fusion Science (NIFS) in Japan. The target parameters of CFQS are as follows: toroidal periodic number N = 2, major radius R = 1.0 m, aspect ratio R/a = 4.0 and magnetic field...
Dr
Wulyu Zhong
(CnSWIP)
25/10/2018, 08:30
Poster
In HL-2A H-mode plasmas, the confinement and pedestal response to impurity seeding have been recently investigated [1]. It has been observed that a broadband electromagnetic (EM) turbulence can be driven by peaked impurity density profile at the edge plasma region, and governed by double critical gradients of the impurity density [2]. In addition to the spontaneously accumulated impurity, the...
Dr
Rui Coelho
(Instituto de Plasma e Fusão Nuclear / Instituto Superior Técnico)
25/10/2018, 08:30
Poster
The reconstruction of Tokamak plasma equilibrium is a fundamental step in the understanding of fusion plasma physics since it sets the starting point for all subsequent plasma modelling applications and experimental data interpretation. The verification and validation of the numerical codes used to reconstruct plasma equilibrium, using as many available input experimental data e.g. magnetic...
Prof.
A.V. Burdakov
(Budker Institute of Nuclear Physics SB RAS, Novosibirsk, Russia)
25/10/2018, 08:30
Poster
The challenge of creation of an open trap with the reactor-grade plasma is achievable if such trap will use specialized sections of the magnetic system for suppression of particle and energy losses along the magnetic field. Currently, two new experimental devices are under construction in the Budker Institute for studies of physics of plasma confinement in magnetic systems with multiple-mirror...
Dr
Longwen Yan
(Southwestern Institute of Physics)
25/10/2018, 08:30
Poster
The stability and performance of tokamak plasmas are routinely limited by various magneto-hydrodynamic (MHD) instabilities, such as neoclassical tearing modes (NTMs). This paper presents a rather simple method to control the NTMs in real time (RT) on a tokamak, including the control principle of feedback approach for RT suppression and stabilization for the NTMs. The control system combines...
Dr
Leonardo Pigatto
(ItRFX)
25/10/2018, 08:30
Poster
The superconducting tokamak JT-60SA is being built in Naka (Japan) under the Broader
Approach Satellite Tokamak Programme jointly by Europe and Japan, and under the Japanese
national programmme. JT-60SA has an important supporting mission for the development of
fusion energy: designed to achieve long pulses (100 s) and break-even equivalent plasmas,
challenging high $\beta$ operation...
Dr
Yueqiang Liu
(General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA)
25/10/2018, 08:30
Poster
Edge localized modes (ELMs) release large bursts of heat and particle flux to the plasma facing components in tokamaks, potentially causing significant material erosion in future devices such as ITER. Externally applied three-dimensional (3D) resonant magnetic perturbations (RMP) have been experimentally demonstrated to be effective in tailoring these ELM bursts. A significant yet not well...
Zhihong Lin
(UC Irvine)
25/10/2018, 08:30
Poster
Resonant magnetic perturbations (RMPs) can be used to mitigate or fully suppress the harmful Edge Localized Modes (ELMs). In DIII-D, the ELM suppression is observed to be correlated with the enhanced particle and heat transport near the pedestal top. Initial simulations using Gyrokinetic Toroidal Code (GTC) show that the kink responses to the 3D RMP have little effect on the growth rate of...
Mr
Craig Bowie
(Australian National University)
25/10/2018, 08:30
Poster
Sandpile models have been used to provide simple phenomenological models without incorporating the detailed features of a fully featured model. The Chapman sandpile model (Chapman et al *Physical Review Letters* 86, 2814 (2001)) has been used as an analogue for the behaviour of a plasma edge, with mass loss events (MLEs) being used as analogues for (and anagrams of) ELMs. Here we modify the...
Mr
Jervis Mendonca
(Institute for Plasma Research Gandhinagar INDIA)
25/10/2018, 08:30
Poster
The (m=1, n=1) internal kink instability plays an important role in the dynamics of a
tokamak discharge and is responsible for the occurrence of sawtooth oscillations. Many
experimental observations show that plasma rotation can strongly influence the
stability properties of sawtooth oscillations. Past theoretical flow studies to understand such stabilization have been done in the low...
Dr
Vadim Prikhodko
(Budker Institute of Nuclear Physics SB RAS)
25/10/2018, 08:30
Poster
Interest to magnetic mirrors went missing in the 1980's because of three key problems: magnets' complexity, micro-instabilities, and low temperature of plasma. However, researches on the Gas Dynamic Trap (GDT) device at the Budker Institute of Nuclear Physics demonstrates the possibility to overcome these difficulties. Confinement of plasma with high energy density have been performed on GDT...
Dr
Wei Chen
(Southwestern Institute of Physics, P.O. Box 432 Chengdu 610041, China)
25/10/2018, 08:30
Poster
Magneto-hydrodynamic (MHD) instabilities in hot plasmas can strongly limit the operational parameter space of a fusion reactor. Their stabilization, suppression and active control have therefore attracted much attention, in particular with regard to expansion of the operational space, enhancing the fusion performance and decreasing the energetic particle losses in both present-day fusion...
Dr
Matthew John Hole
(Australian National University)
25/10/2018, 08:30
Poster
Edge Localised Modes (ELMs) are thought to be caused by a spectrum of magnetohydrodynamic instabilities, including the ballooning mode. While ballooning modes have been studied extensively both theoretically and experimentally, the focus of the vast majority of this research has been on isotropic plasmas. The prevalence of pressure anisotropy in modern tokamaks thus motivates further study of...
Dr
Gleb Kurskiev
(Ioffe Physical-Technical Institute of the Russian Academy of Sciences)
25/10/2018, 08:30
Poster
The presentation is devoted to the overview of thermal energy confinement time study at the compact spherical tokamak Globus-M. Globus-M has major radius R = 0.35 m and minor radius a = 0.21 m (R/a ~ 1.6). The lower-null magnetic configuration is characterized by moderate elongation k~1.9 and triangularity δ~0.35. The present study was performed in both OH and NBI heated H-mode plasma. The...
