Description
All posters will be displayed in both sessions on Tuesday and Wednesday.
Disruption prediction and avoidance is critical to maintain steady plasma operation and to avoid damage to device components in ITER and reactor-scale tokamaks. Physics-based disruption event characterization and forecasting (DECAF*) research determines the relation of events leading to disruption, and aims to provide event onset forecasts with high accuracy and sufficiently early warning to...
The inboard-wall runaway electron mitigation coil (REMC) designed for DIII-D was optimized based on vacuum island overlap width (VIOW) [1] and subsequently modeled with the linear MHD code MARS-F [1] and the non-linear MHD code NIMROD [2]. Both the linear and non-linear MHD modeling tracked the confinement of an initial RE test population, with the total loss fraction for the nonlinear model...
Vertical displacement events (VDEs) in tokamaks involve large displacements of the plasma magnetic axis from the vessel midplane, often leading to disruptions. These events are of particular concern for their potential to cause damage to plasma-facing components, as well as large forces on the vessel due to halo currents generated during the disruption that run through the plasma and vessel...
Unmitigated disruptions at high performance discharge are unacceptable for future reactors, while they are not able to provide enough data to train a predictor with acceptable performance along. However, current can bear disruptions, and have accumulated a large amount of data with various disruption patterns. In the meantime, domain adaptation (DA) and domain generalization (DG) are now very...
The structural integrity of the Vacuum Vessel (VV) of Pakistan's Metallic Tokamak-I (MT-I), a small spherical tokamak, was tested by simulating a 10 ms input current event on a 180° sector model. During this event, the energy from the plasma is entirely transferred to the VV's first wall. This study is based on the law of conservation of energy, demonstrating that the extent of damage is...
A pulsed hydrogen plasma stream is produced from a pulsed plasma accelerator (PPA) powered by 200 KJ Pulsed Power System (PPS). The PPS, which consists of two modules capacitor banks, is charged up to 15 kV to generates a peak discharge current of 100 kA for a half time period of 500 µs. The high voltage from the capacitor banks thus applied in between two coaxially positioned electrodes to...
Disruption of a tokamak plasma is a multi-step process in which the loss of the plasma vertical position control is often among the last events that precede the final plasma deconfinement. A flow of current between the plasma and the vessel components -the halo current [1]- is generated through the contact of vertically displaced plasma with the vacuum vessel, resulting in electromagnetic...
We present a groundbreaking multimodal neural network model designed for diagnostics resolution enhancement, which innovatively leverages inter-diagnostic correlations within a system. Traditional approaches have primarily focused on unimodal enhancement strategies, such as pixel-based image enhancement or heuristic signal interpolation. In contrast, our model employs a novel methodology by...
Runaway plateaus have been formed in EAST disruptions via massive argon injection into low-density ohmic discharges, which are carried out with circular plasma and limiter configuration in full-metal wall condition. REs are detailly described in the following three phases:
Formation: Formation of runaway plateau is found strongly depends on pre-disruption density and amounts of injected...
In the past three years, a shattered pellet injection (SPI) system designed for disruption mitigation on the EAST tokamak was successfully developed and integrated into EAST tokamak in 2022. The SPI system is capable of producing Ne pellets with diameters of ~ 5 mm and lengths ranging from 7 to 15 mm. The material gas consumption is approximately 20, 25, and 30 Pa·m3, respectively, and the...
Plasma major disruptions pose severe threats to the device integrity in future operations of International Thermonuclear Experimental Reactor (ITER). They can cause dangerous excessive electromagnetic forces, heat loads and generation of the intense beams of relativistic runaway electrons (RE). Localized interaction of intense RE beams with surrounding plasma facing components (PFC) inevitably...
In this work we report measurements of the temperature and density of the halo current region on DIII-D during disruptions using the recently upgraded Thomson scattering diagnostic allowing low-temperature measurements down to a few eV with a sub-ms repetition rate. This is done by employing deliberate downward vertical displacement events (VDEs) and relying on the expansion of the halo...
Dispersive shell pellet (DSP) injection is currently being developed as an alternative disruption mitigation technique to massive gas injection and shattered pellet injection. The main advantage of DSP injection is the core deposition of the payload which is expected to result in higher assimilation fractions and an inside-out thermal quench (TQ). DSPs have been successfully launched into...
Disruptions are an inherent property of tokamak plasmas, which cannot be completely eliminated. The consequences of disruptions are especially dangerous for large machines like ITER and even more so for DEMO. Thermal Quench (TQ) is the initial phase of disruption followed by plasma Current Quench (CQ). Essential diagnostics for the TQ are magnetics (dB/dt), Electron Cyclotron Emission (ECE)...
The Learning Using Privileged Information (LUPI) paradigm allows training classifiers with data not available at execution time. Recently, an application of the LUPI paradigm to the prediction of disruptions with extreme data scarcity was demonstrated [J. Vega et al. Nuclear Fusion 64 (2024) 046010 (12 pp)]. The objective of the previous reference was to test the development of an adaptive...
The ITER Disruption Mitigation System (DMS) is based on Shattered Pellet Injectors (SPI), which accelerates a large protium, neon or mixture pellet with high pressure gas and shatters it prior to the entrance into the plasma, creating a plume of smaller pellet fragments. The ITER DMS Support Laboratory is part of the ITER DMS Task Force programme to establish the physics and technology basis...
Future tokamaks will require disruption mitigation systems (DMS) to prevent machine damage during the uncontrolled loss of plasma confinement. Massive impurity injection, particularly shattered pellet injection (SPI), is the leading candidate for a DMS. Validated, predictive models are needed to project these systems to future devices, which require models for the macroscopic plasma evolution...
Abstract
The magnitude of the electromagnetic forces expected during and after a vertical displacement event (VDE) of a tokamak plasma is a necessary design parameter for the structural design of the many components of the tokamak device. During and after a VDE, the plasma current moves, changes in time and induces currents in the conductors around the plasma. The total vertical force
on the...
Weibel instability due to nonlinear inverse bremsstrahlung absorption (WINLIBA) in magnetized plasma has been investigated in the frame of the relativistic kinetic theory (RKT). In this study the magnetized plasma is described by relativistic Fokker-Planck equation with an ameliorated Krook collision term which takes into account the relativistic effect and the Landau microscopic collision...
