A significant advancement of RF modeling was achieved by realizing for the first time the entire 3D full torus plasma simulation with detailed 3D realistic antenna and SOL plasma. Many experiments in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves (HHFW), have found strong interactions between RF waves and the SOL region. In a...
Access to high current (IP >~ 1 MA) relativistic electron (RE) beams in the DIII-D and JET tokamak reveal excitation of current-driven (low safety factor) kink instabilities that promptly terminate the RE beam on an Alfvenic time-scale [Ref. 1], a phenomenon first observed during the early JET carbon wall operation period. Unlike past results however, this phenomenon when combined with the...
Joint research on the tokamaks DIII-D and EAST demonstrates a successful integration control of divertor detachment with excellent core plasma performance, a milestone towards solving the critical Plasma-wall-interaction (PWI) issues for ITER and future reactors. DIII-D has achieved actively controlled fully detached divertor with low plasma temperature ($T_{e,div} \le $ 5 eV across the entire...
Novel disruption prevention solutions spanning the range of control regimes have been developed and tested on DIII-D to enable ITER success. First, the disruption risk during fast, emergency shutdown after large tearing and locked modes can be significantly improved by transitioning to a limited topology during shutdown. More than 50% of limited shutdowns reach a final normalized current $I_N$...
An optimized pedestal regime called the Super-H Mode (SH-mode) is leveraged to simultaneously couple a fusion relevant core plasma with a scrape-off layer appropriate for realistic reactor exhaust solutions. Recent DIII-D experiments have expanded the operating space from previous studies of the SH regime and investigated optimization of impurity seeding, deuterium gas puffing, 3D magnetic...
New scaling laws and modeling, developed at DIII-D and benchmarked with data from JET and KSTAR, provide a path for projecting Shattered Pellet Injection (SPI) performance to ITER, while improved understanding of higher-order effects such as asymmetries better constrain the expected behavior. In the limit of radiative shutdown by high-Z impurity injection, the volume-averaged performance of...
ITER adopts a strategy that distributes radiated power evenly during the disruption mitigation and reduces the time to prepare pellets, using simultaneous multiple shattered pellet injections (SPIs)$^1$. However, since there were no existing devices with perfectly symmetric SPIs, as planned in ITER$^2$, sufficient studies have not been conducted on the effects of simultaneous multi-injections....
Diverted discharges at negative triangularity on the DIII-D tokamak (figure [1]a) sustain normalized confinement and pressure levels typical of standard H-mode scenarios ($H_{98,y2}\simeq 1$, $\beta_N\simeq 3$) without developing an edge pressure pedestal (figure [1]b), despite the auxiliary power far exceeding the L→H power threshold expected from conventional scaling laws. The power...
For the first time, experiments on the DIII-D tokamak have demonstrated electron cyclotron current drive (ECCD) with more than double the efficiency of the conventional outside launch by using a novel top launch geometry (figure 1), as predicted by linear ray tracing and quasi-linear Fokker-Planck simulations. Studies have shown that off-axis current drive is a requirement for a steady-state...
Recent EAST experiment has successfully demonstrated long pulse steady-state high plasma performance scenario with core-edge integration since the last IAEA in 2018 $[1]$. A discharge with a duration over 60s with $\beta_P$ ~2.0, $\beta_N$ ~1.6, $H_{98y2}$~1.3 and internal transport barrier on electron temperature channel is obtained with multi-RF power heating and current drive, i.e. ~2.5 MW...
Next step fusion devices such as ITER will need a reliable method for controlling the quasi-periodic expulsion of a large amount of heat and particles onto the plasma-facing components caused by edge-localized modes (ELMs). Several options are currently being considered to achieve the required level of ELM-crash control in ITER; this includes operation in plasma regimes which naturally have no...
Full suppression of Edge Localized Modes (ELMs) by using n=4 resonant magnetic perturbations (RMPs) has been demonstrated for ITER for the first time (n is the toroidal mode number of the applied RMP). This is achieved in EAST plasmas with low input torque and tungsten divertor, thus also addressing significant scenario issues for ITER. In these conditions energy confinement does not drop...
Injection of boron powder in the EAST X-point showed edge-localized mode (ELM) suppression with no confinement degradation over a wide range of operations. The work shows that ELM suppression was achieved by making the pedestal marginally "leaky” via an edge-localized GAM-induced particle transport. This approach potentially opens up novel methods for increasing the ELM suppression toolbox for...
1.Introduction
The inductive goal of ITER is to produce 500s long burning plasmas with $Q=P_{fus}/P_{aux}\geq$10[1]. This requires the development of operationally robust scenarios that span the whole plasma discharge from start-up to termination not only in Deuterium Tritium (DT) but also in the Pre Fusion-Plasma Operation (PFPO) phase in Hydrogen (H) and Helium (He). In the PFPO phase,...
Recent experiments in the DIII-D tokamak have shown that a broadened fast-ion pressure profile enables better control of Alfvén Eigenmodes (AEs), improves fast-ion confinement, and allows access to new regimes. New discharges reach 15% higher normalized plasma beta ($\beta_N$) than previously achieved in steady-state scenarios with negative central shear and $q_{min}>2$ at high field...
ITER high Q operation requires the integration of high performance plasmas with high plasma density, good fast ion confinement with acceptable stationary and transient power fluxes to plasma facing components (1). To control transients associated with high performance plasmas (Edge Localized Modes or ELMs), ITER is equipped with a set of in-vessel coils that modify the edge magnetic field...
In the study of burning plasmas it is important to understand multi-scale interactions between energetic-particle-driven MHD mode and drift-wave turbulence for establishing good confinement of both energetic particles and bulk plasmas simultaneously. We investigate nonlinear multi-scale interactions between TAE, which is unstable at low $n$, and drift-wave turbulence, which is driven by...
Detailed new H-mode pedestal measurements in the inter-ELM periods of DIII-D discharges find that ion temperature gradient (ITG)-scale density fluctuations (ñ) can explain anomalous ion heat flux (Q$_{i}$) during the ELM (Fig. [1]), followed by Q$_{i}$ becoming neo-classical$^{1}$ until the next ELM, and with trapped electron mode (TEM) and microtearing mode (MTM) like ñ and magnetic...
An accurate and predictive model for turbulent transport fluxes driven by microinstabilities is a vital component of first-principle-based tokamak plasma simulation. However, tokamak scenario prediction over energy confinement timescales is not routinely feasible by direct numerical simulation with nonlinear gyrokinetic codes. Reduced order modelling with quasilinear turbulent transport models...
A predictive 3D optimizing scheme in tokamaks is revealing a robust path of error field correction (EFC) across both resonant and non-resonant field spectrum. The new scheme essentially finds a way to deform tokamak plasmas in the presence of non-axisymmetric error fields while restoring a quasi-symmetry in particle orbits as much as possible. Such a “quasi-symmetric magnetic perturbation”...
A small angle slot (SAS) divertor concept [1] with a closed slot structure and appropriate target shaping in the near SOL has been developed in order to explore a potentially robust boundary solution with acceptable plasma surface interaction which is essential for fusion reactor plasma conditions, in particular for high-power steady-state operation. Recent experimental tests in DIII-D have...
KSTAR has clarified a set of unresolved 3-D physics issues that could be addressed in the ITER-like in-vessel 3-row, resonant magnetic perturbation (RMP) configurations. In particular, considering that one of the most critical metrics of RMP ELM-crash control would require the compatibility with the divertor heat fluxes under the given material constraints, a series of intentionally misaligned...
For the first time, the progress in RF full wave modeling allows for simulating the wave field in arbitrary 3D antenna/first wall geometry together with the scrape-of-layer (SOL) and the entire tokamak/stellarator core plasmas in an integrated manner. Universal observation among many RF heating and current drive (H/CD) experiments in the ion cyclotron (IC), high-harmonic fast waves (HHFW),...
ITB formation due to energetic particles. The performance of present-day and future fusion devices is largely determined by turbulent transport generated by plasma turbulence. Any mechanisms able to reduce the overall radial propagation of energy and particles is, therefore, crucial in view of scenario optimization. This contribution presents numerical results of turbulence suppression by...
Topic: TH
Type: Oral synopsis
A full-discharge tokamak flight simulator
E. Fable, F. Janky, O. Kudlacek, M. Englberger, R. Schramm, W. Treutterer, C. Angioni, F. Palermo, M.
Siccinio, H. Zohm, and the ASDEX Upgrade Team
Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching bei München, Germany
e-mail: emf@ipp.mpg.de
Operation of a plasma discharge in a tokamak...
Most of high-performance discharges based on the advanced scenario have shown the active generation of the Alfvén eigenmodes (AE), driven by enhanced fast-ion pressure gradient and broad current density profile in the core region$^{1,2}$.
Among various AE control tools, it has been found that the ECCD and ECH are able to mitigate or suppress the toroidal Alfvén eigenmodes (TAE) and the...
The neutron and tritium production during the pre-DT, Pre-Fusion Plasma Operation, (PFPO) phase of ITER need to be quantified in view of the plans for commissioning and operation of the heating systems in hydrogen and helium plasmas, as discussed in the ITER Research Plan (IRP) [1]. In the assessment presented here, we consider a number of tritium and neutron sources of different origins. In...
The primary goal of Tokamak based fusion reactors is to achieve a self-sustained plasma satisfying ignition criterion by maximizing the product of plasma density, temperature and energy confinement time. There are limits on achievable plasma density and temperature due to current driven or pressure driven instabilities. Also, the Tokamak performance can be enhanced by operating with advanced...
The steady-state superconducting tokamak (SST1) [ref1], having major and minor radius of 1.1m and 0.2 m respectively, equipped with a Copper-based central solenoid to provide the required loop voltage. Like in other superconducting tokamaks [ref2-3], SST1 tokamak also relies on ECR breakdown technique to form Ohmic plasmas. Plasma preionization and current start-up is assisted by the 42 GHz...
Regulation of the $q$ profile via feedback control has been recently demonstrated in EAST in both L-Mode and H-mode experiments. Extensive studies have shown that the $q$ profile, which is closely related to poloidal magnetic flux profile, is a key factor to achieving advanced-tokamak operating scenarios that are characterized by improved confinement and the non-inductive sustainment of the...
A novel integrated model GOTRESS+ has been developed, which consists of the iterative transport solver GOTRESS as a kernel of the integrated model$^{1,2}$, the equilibrium and current profile alignment code ACCOME and the neutral beam heating/current-drive code OFMC. GOTRESS is able to find out an exact steady-state solution using global optimization techniques, enabling us to robustly deal...
Experiments have been carried out to explore quiescent H-mode (QH-mode) $[1]$ scenario under the condition of low torque and pure RF injection (true zero torque) with ITER like tungsten divertor on EAST, which will facilitate the eventual use of this scenario on ITER and other reactors. EAST achieved the stationary QH-mode over 50-80 energy confinement time or 3-6 current relaxation time with...
Simultaneous control of large ELMs and divertor heat load in a metal wall environment is crucial for steady-state operation of a tokamak fusion reactor. A new scenario for ELM suppression compatible with radiative divertor has been demonstrated, for the first time, in the EAST superconducting tokamak. An n = 1 mode [FIG 1(f)] along with its harmonics, initiating from the oscillation of a...
I-mode, a plasma regime with high energy confinement similar to H-mode and edge particle transport comparable to L-mode, represents a potential and credible solution alternative to H-mode for standard operation scenario in the future fusion reactor [1-3]. It is characterized by a very sharp edge temperature pedestal without edge density pedestal and ELMs. More interesting, it has the following...
For future fusion devices including ITER and DEMO, it is crucial to handle the power flux to the divertor targets in order not to exceed the steady-state material limit, q$_{t,⊥}$≤ 10 Wm$^{-2}$ [Ref. 1]. One of the viable effective methods to achieve it under development is divertor detachment via impurity gas seeding or deuterium injection in the divertor region in order to dissipate the...
The configuration of reversed shear q(r)-profile is existence for the burst of sawteeth-like events, and the collapse is triggered periodically by the magnetic reconnection of double tearing modes (DTM) [1], with abbreviation of DTRC (double tearing reconnection crash). The excitation conditions of DTRC has strong relationship with the impurity ions, the power threshold of ECRH, the influence...
Successfully confining, and heating D and DT plasmas in tokamaks results in the emission of neutrons, which carry a part of the excess energy produced in the fusion of fuel ions. Upon escaping the magnetic confinement neutrons effectively transfer fusion energy generated in the plasma to the device’s first wall and other tokamak components, such as plasma diagnostics. In future fusion devices...
Recent control advances at KSTAR enabled us to not only sustain the ITER-similar shape (ISS) in a stationary manner but also experimentally demonstrate the ISS-compatible RMP-ELM control in KSTAR for the first time, using the n=2, +90-deg phasing RMP, matching the ITER-like dimensionless parameters in lower single null (LSN) configuration with vastly contrasting upper/lower triangularities....
Introduction
Flexible and easy-to-use extrapolation tools are needed for extrapolating to, and planning for, the forthcoming JET DT campaign (DTE2) $[$1$]$. For this purpose and based on the needs of the scientific teams involved in scenario development, a streamlined, automated analysis workflow for the ASCOT heating and fast particle following code [2,3] has been developed....
The Divertor Tokamak Test facility (DTT) [1-3] is a D-shaped superconducting tokamak (R=2.14 m, a=0.65 m, BT≤6 T, Ip≤ 5.5 MA, pulse length ≤ 100 s, auxiliary heating ≤ 45 MW, W first wall and divertor), whose construction is starting in Frascati, Italy. Its main mission is to study the controlled exhaust of energy and particle from a fusion reactor, which is a top priority research item in the...
Due to edge opacity, future tokamaks will rely on injection of cryogenic pellets for plasma fuelling. Maintaining the desired density and isotope composition crucially depends on the transient plasma response to pellet injection, motivating dedicated studies for increased understanding and predictive capabilities. In a recent experiment at the Joint European Torus (JET), Deuterium pellets...
Introduction and motivation.
Numerical simulations with the EIRENE [1] code are indispensable for both understanding and predicting the fuel and impurity transport in the edge and divertor areas of fusion devices including ITER. The transport determines impurity penetration towards the core, plasma exhaust and plasma-surface interaction (PSI) issues. The insight into the interplay of...
The toroidal rotation without any external momentum sources known as an intrinsic rotation has been focused an important topic since the most promising toroidal rotation source driven externally from a neutral beam injection may not successful for the future burning devices like ITER and DEMO. The toroidal rotation in pure ohmic plasmas is self-generated and it is considered as one of the most...
The helium plasmas have been demonstrated for the first time on EAST under the condition of pure RF-heating and ITER-like tungsten divertor, which advances physical understanding in support of the ITER non-nuclear operational phase $[1]$. Concentration of helium ($C_{He}$) in the plasma is confirmed to play a critical role in H-mode operation, as higher concentration raises the H-mode...
Hybrid scenarios are under development in KSTAR which are defined as “stationary discharges with β_N ≥ 2.4 and H_89 ≥ 2.0 at q_95 < 6.5 without or very mild sawtooth activities”. β_N≲3.0, H_89≲2.4 and G-factor (≡β_N H_89/q_95^2) ≲0.46 has been obtained simultaneously at ne/nGW~0.7 and sustained for ≳40 τ_E during the main heating phase as shown in figure 1.
![A representative hybrid...
Development of high performance operation regimes in the magnetic confinement fusion devices has been of great interest in the fusion community for decades as it is critical to accomplish efficient steady-state operations of fusion reactor. Since the first discovery of high confinement mode (H-mode) in tokamaks that claimed enhancement of energy confinement by more than a factor of 2 compared...
Plasma-wall interaction (PWI) processes are important in long-pulse plasma operation of fusion devices due to the main issues of increased fuel retention, material erosion and redeposition which are induced by a large increase in particle fluence to the wall compared to present experiments. The in situ approach is an urgent requirement to be utilized to real-time measure the fuel content on...
Leading edge induced material damages are very critical in future fusion devices which may have cassette structure for plasma facing components [1]. The upper tungsten divertor in EAST is the first application of active cooled ITER-like W/Cu monoblocks modules in a tokamak [2]. The misalignment between neighboring monoblocks was formed inevitably during fabrication and assembly processes,...
The high-performance operation is one of the major missions of HL-2M [1, 2] for supporting ITER, CFETR and future fusion reactors. Notice that, high-performance scenarios with the large plasma current (2.5-3MA) and the high elongation (1.8-2.0) are normally accompanied by the potential VDEs risk. This requires an efficient and reliable feedback control system, which is under construction. This...
The Integrated Modelling & Analysis Suite (IMAS) is the software infrastructure that is being developed building upon the modelling expertise from across the research facilities within the ITER Members to support the execution of the ITER Research Plan [1]. It is built around a standardised representation of data described by a Data Dictionary that is both machine independent and extensible. ...
Disruption prediction and avoidance is a high-priority challenge for tokamaks to sustain long pulse and high performance plasmas that are critical for ITER and next-step devices for fusion generation. Disruption-free, continuous operation of high performance plasmas over long pulse is a main goal of modern superconducting tokamak devices such as the Korea Superconducting Tokamak Advanced...
Control of impurity species in fusion plasmas is one of the main issues for long and stable plasma operation. The impurities can be generated by interaction of the plasma with its facing materials and/or by intentional injection for the purpose of maintaining radiative mantle. These impurities can cause detrimental radiation cooling and fuel dilution as they become accumulated inside the...
Repetitive buildup and collapse of the edge confinement barrier (called pedestal) in H-mode plasmas can seriously damage the plasma-facing components in tokamak fusion devices [1]. Hence, an accurate understanding of the underlying mechanism of the collapse is essential for the safe operation of fusion devices. We have proposed the formation of a solitary perturbation (SP) in the edge as a...
Kinetic plasma control based on extremely simple data-driven models and a two-time-scale approximation has been developed and validated on non-linear plasma simulations in recent years. Both in these models and in the associated control algorithms, the fast component (kinetic time scale) of the plasma dynamics is considered as a singular perturbation of a quasi-static magnetic and thermal...
Introduction
Compass-Upgrade tokamak, which is being constructed in the Institute of Plasma Physics of the Czech Academy of Sciences in Prague, will replace existing Compass tokamak $[1]$. It will be a compact, medium-size ($R=0,89 m, a=0,3 m$), high-magnetic-field ($5 T$) device. The tokamak is expected to operate with plasma densities up to $n_e=10^{21} m^{-3}$. Plasma heating will be...
Successful operation of ITER will require robust regulation of the plasma temperature and density despite the plasma's nonlinear dynamics and various uncertainties. In this work, a burn-control algorithm was designed to determine control efforts that will drive the plasma to desired targets. In order to effectively achieve the commanded control efforts, control allocation modules were...
$\quad$Plasmas with a high runaway electron (RE) current fraction, $f_{RE}$ > 0.5, have been achieved during the flat-top of EAST Ohmic discharges with both a circular limited and an X-point diverted configuration. Low toroidal mode number Alfvén eigenmodes (AE) in the frequency range of 100-300kHz including TAE, KTAE and GAE, which are excited by low-energy REs, are clearly identified in the...
Helium (He) operation has recently been successfully performed on EAST equipped with an upper ITER-like, water-cooled, tungsten (W) monoblock divertor. The main plasma-wall interaction issues in He plasmas have been studied and compared with those in deuterium (D) plasmas, such as divertor detachment, W erosion, material migration, ELM characteristics and control, etc. Studying the impact of...
Possible ways to suppress anomalous absorption at ECRH
E.Z. Gusakov, A.Yu. Popov
Ioffe Institute, St.-Petersburg, Russia
Possible approaches which allow reducing of anomalous absorption rate associated with the low-power-threshold two-UH-plasmon parametric decay instability, which is excited by the extraordinary pump wave in the X2 ECRH experiments in the vicinity of the plasma...
Preparation of the ITER experimental campaigns will require use of verified and validated models for the prediction of plasma response to actuators and of fusion performances. Several simulation codes have been developed by the fusion community for modelling of plasma equilibrium, transport processes, MHD stability, heating and current drive and fusion reactions. The integration of these codes...
The practical and economic viability of tokamak fusion reactors depends, in a significant way, on the efficiency of radio frequency (RF) waves to deliver energy and momentum to the plasma in the core of the reactor. The RF electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the turbulent edge plasma along their path to the core of...
The quasioptical ray tracing code named PARADE (PAraxial RAy DEscription) [a,b], which can contribute to the modeling of propagation and absorption of wave beams in both tokamak and stellarator, is newly developed based on the eXtended Geometrical Optics (XGO) theory [c]. Transmitted power profile of Electron Cyclotron Waves (ECWs) experimentally observed in Large Helical Devise (LHD) [d,e]...
KSTAR has a mission such as achieving a pulse length for more than 300 seconds and achieving a high-performance plasma[1]. The pulse length of the KSTAR discharge has increased each year gradually. Assigned research on the long pulse operation in KSTAR has been conducted since 2015. The pulse length of 90 seconds is achieved in the 2018 KSTAR experimental campaign.
The high $\beta_{P}$...
The electron cyclotron heating (ECH) is one of the intense methods of non-inductive plasma current drive (CD). The ECH waves accelerated the electrons with the Doppler-shifted electron cyclotron resonance (ECR) interactions, and effectively ramped and sustained the plasma current non-inductively to achieve long discharge duration. The plasma sustainment with ECH waves is a key issue for the...
Plasma waves naturally occur in various forms in magnetically confined plasmas. With a broad categorization into cold waves, hot (kinetic) waves, and coupled cold-hot waves, the plasma waves play integral functions in fusion plasma physics, such as particle confinement, fluid instabilities, and radiative processes. Some plasma waves, in particular low-frequency electrostatic (ES) waves, affect...
Chinese Fusion Engineering Testing Reactor (CFETR) aims to bridge the technical gaps between ITER and the first commercial fusion power plant [1]. The physics design of the operation scenarios should provide an integrated solution for the plasma to meet the key mission goals for CFETR subject to engineering constraints. For this purpose the optimization of scenarios and the exploration of...
Studies are carried out examining the dependence and sensitivity of fusion power production, temperature and density pedestals on edge density fueling strength, current density profile, alpha heating, and magnetic field strength. The goal of these integrated ITER simulations is to identify dependencies that can impact ITER fusion performance.
The self-consistent predictive core-pedestal...
The Advanced FRC is a Field Reversed Configuration maintained by neutral beam (NB) injection and electrode biasing (EB), with scrape-off-layer (SOL) pumping and electron heat confinement provided by expander divertors. This alternate magnetic confinement system has been developed at TAE Technologies, Inc in the C-2 [1,2], C-2U [3,4], and C-2W [5] series of devices. In this paper we summarize...
Tearing modes with poloidal/toroidal mode numbers $m$/$n$ = 2/1 have been routinely observed in KSTAR [1] with modes having notably large amplitude leading to significantly reduced both normalized beta, $\beta_N$, and plasma stored energy. Global kink/ballooning or resistive wall modes (RWMs) are observed to be stable at high $\beta_N$ above the $n$ = 1 ideal MHD no-wall stability limit,...
Recently, improved high-performance plasma operation has been significantly extended towards more ITER and CFETR related high beta steady-state regime with optimization of current profile (βP ~ 2.5 & βN ~ 1.9 with ITB +ETB of using RF & NB and βP ~ 1.9 & βN ~ 1.5 with eITB + ETB of using pure RF) on EAST [1]. The ITB formation and sustainment company with optimization of the current profiles,...
The KSTAR uses the NBI (neutral beam injection) as a majority of heating and current drive and has been exploring the inboard-limited ITB (Internal Transport Barrier) as an alternative candidate to achieve a high performance regime since 2016. The approach with the inboard limited configuration to avoid the H-mode transition prior to the formation of the ITB was effective at a given L-H...
Lower hybrid waves (LHW) are absorbed in the scrape-off layer (SOL), and then the heated plasma follows the magnetic field lines in the co-current and counter current directions, which intercepts the LHW antenna limiter and divertor plate [1,2]. Hot spots are observed on the guard limiter, and heat flux striations on the divertor plate are observed on both the ion and electron drift sides. In...
Of the three additional heating methods envisaged for ITER, waves in the Ion Cyclotron Range of Frequencies (ICRF) are attractive as the only one capable of ion heating and central deposition at high density. Yet, since their first use in magnetic fusion devices, the non-linear interaction of ICRF waves with the Scrape-Off Layer (SOL) plasma has attracted attention. This interaction is now...
Disruption prediction and avoidance is critical for ITER and reactor-scale tokamaks to maintain steady plasma operation and to avoid damage to device components. The present status and results from the disruption event characterization and forecasting (DECAF) research effort (1) are shown for multiple tokamak devices. Access to the full KSTAR, MAST, NSTX, AUG, TCV, and DIII-D databases is...
Disruptions can have root causes in density limits, radiation cooling of the edge or MHD instabilities. The latter include external kink modes, tearing modes and Neoclassical Tearing Modes (NTM) that slow down and can eventually lock to the wall {1}. Operating a tokamak with lowest disruption rate is not only a matter of understanding the stability limits of a plasma, but also of developing a...
To predict energy and particle transport in future tokamaks we cannot use experimental measurements as boundary condition. Therefore, we need integrated modelling from the SOL to the plasma center.
On the other hand, transport in the various plasma regions is known to different degree. In order to increase our confidence on the transport predictions, we need to validate the available...
Tungsten is foreseen as plasma facing material in next generation tokamaks (ITER/DEMO). It is thus crucial to understand and predict tungsten transport to prevent detrimental behaviour such as central tungsten accumulation leading, in worst scenarios, to disruptions.
In the framework of integrated modelling, ASDEX Upgrade and WEST discharges (both machines operating in full tungsten...
The development of tokamak start-up operation scenario often relies on operator’s experiences, rather than more robust approach based on numerical modelling. Such a trial-and-error approach has fortunately worked to find start-up recipes in small or medium size devices, but increases the risk of delays to experiments. Moreover, it would not be appropriate anymore for a large superconducting...
