A5010559657- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Electromagnetic Launch and Propulsion Technology
- Nuclear reactor physics and engineering
- Particle accelerators and beam dynamics
- Nuclear Materials and Properties
- Metal and Thin Film Mechanics
- Electrohydrodynamics and Fluid Dynamics
- Advanced Surface Polishing Techniques
- Nuclear Physics and Applications
- Erosion and Abrasive Machining
- Laser-induced spectroscopy and plasma
- Catalytic Processes in Materials Science
- Plasma Applications and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Diamond and Carbon-based Materials Research
- Energetic Materials and Combustion
- Digital Holography and Microscopy
- Advanced Machining and Optimization Techniques
- Petroleum Processing and Analysis
- Laser-Ablation Synthesis of Nanoparticles
- Pulsed Power Technology Applications
Oak Ridge National Laboratory
2017-2025
Culham Science Centre
2024
Culham Centre for Fusion Energy
2024
University of Florida
2015-2018
Virginia Tech
2013-2014
The technology to form and shoot high-Z cryogenic solid pellets mixed with deuterium using a gas gun that are shattered upon injection into plasma has been developed at Oak Ridge National Laboratory for mitigating disruptions. This selected as the basis baseline disruption mitigation system on ITER. development of pellet systems progressed be able accelerate large pure argon neon or without including deuterium. Impact studies have carried out shallow angles determine funnel performance in...
Abstract A series of experiments have been executed at JET to assess the efficacy newly installed shattered pellet injection (SPI) system in mitigating effects disruptions. Issues, important for ITER disruption mitigation system, such as thermal load mitigation, avoidance runaway electron (RE) formation, radiation asymmetries during quench electromagnetic control and RE energy dissipation addressed over a large parameter range. The efficiency has examined various SPI strategies. paper...
Abstract Runaway electrons (REs) created during tokamak disruptions pose a threat to the reliable operation of future larger machines. Experiments using shattered pellet injection (SPI) have been carried out at JET investigate ways prevent their generation or suppress them if avoidance is not sufficient. Avoidance possible SPI contains sufficiently low fraction high-Z material, it fired early in advance disruption prone runaway generation. These results are consistent with previous similar...
Shattered pellet injection (SPI) systems that form cryogenic pellets in a pipe-gun for of material to mitigate disruptions have been fabricated and installed use thermal mitigation runaway electron (RE) dissipation experiments on JET KSTAR. These are support disruption research ITER based an ORNL three-barrel design flexibility size selection variable composition studies. The SPI KSTAR common feature the barrels being collimated into single line enters vacuum vessel. shattered bent stainless...
Shattered pellet injection (SPI) has been selected as the baseline technology for disruption mitigation (DM) system ITER. Typical SPI utilizes cryogenic cooling to desublimate low pressure (<100 mbar) gases onto a cold zone within pipe gun barrel, forming cylindrical pellet. Pellets are dislodged from barrel and accelerated using either gas driven mechanical punch or high-pressure light-gas delivered by fast-opening valve. developed at Oak Ridge National Laboratory is currently deployed...
Abstract Studies have been performed on the release mechanism for large pellets using high pressure gas in a shattered pellet injector. Typically, are dislodged from cryogenic surface and accelerated down barrel delivered by fast-acting propellant valve. The impact an angled which shatters into many small fragments before entering plasma. This technique was initially demonstrated DIII-D (Commaux et al 2016 Nucl. Fusion 56 046007) is now deployed JET, KSTAR, ASDEX-Upgrade, other tokamaks...
The realization of fusion energy requires materials that can withstand high heat and particle fluxes at the plasma material interface. In this work, an electrothermal (ET) source has been designed as a transient flux for linear interaction device. An ET operates in ablative arc regime driven by DC capacitive discharge. current channel width is defined 4 mm bore boron nitride liner. At large currents, impacts liner wall, leading to material, which subsequently ablates ionizes. This results...
Mitigating disruptions is essential for the longevity of future large tokamak experimental devices and reactors. Currently, shattered pellet injection (SPI) technique most effective mitigation found thus far, has been chosen baseline disruption (DM) system ITER. To optimally design SPI systems, survivability throughout pre-shatter flight resulting shatter spray must be better understood. Experimental tests low-angle single strike impacts neon argon pellets were conducted to determine minimum...
Reliable mitigation is necessary to eliminate the detrimental effects of a disruption event in large high-current tokamaks such as ITER. To avoid serious damage plasma-facing components during thermal quench phase disruption, material injected radiate plasma energy over inner surface machine. The most promising method injection process known shattered pellet (SPI). SPI utilizes cryogenic cooling desublimate gas into barrel pipe gun form solid pellet. High-pressure or mechanical punch used...
Shattered pellet injection (SPI) experiments on Joint European Torus (JET) are an important element in determining the physics basis for mitigating disruptions ITER. The initial design of JET SPI system included three barrels to produce pellets with diameters 4.5, 8.1, and 12.5 mm. variability speed by operating without a mechanical punch was limited led poor integrity, so removed. Fragment size distribution is function desire change resulting fragment not originally requirement. After first...
To produce a realistic tokamak-like plasma environment in linear device, transient source is needed to deliver heat and particle fluxes similar those seen an edge localized mode (ELM). ELMs future large tokamaks will of ∼1 GW/m2 the divertor facing components at few Hz. An electrothermal can this magnitude. These sources operate ablative arc regime which driven by DC capacitive discharge. was configured with two pulse lengths tested under solenoidal magnetic field determine resulting impact...
The technology for producing, accelerating, and shattering large pellets (before injection into plasmas) disruption mitigation has been under development at the Oak Ridge National Laboratory several years, including a system on DIII-D that used to provide some significant experimental results. original proof-of-principle testing was carried out using pipe gun injector cooled by cryogenic refrigerator (temperatures <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML"...
A continuous pellet fueling system (CPFS) is currently being designed at the Oak Ridge National Laboratory (ORNL) for long pulse operation of Wendelstein 7-X (W7-X) stellarator. The purpose CPFS to provide deep feedback-controlled high-density and mitigation predicted hollow density profiles. will capability inject cylindrical pellets solid hydrogen or deuterium into plasma core, with flexibility vary size, velocity, injection frequency. Pellets are nominally 3 mm in diameter have a length...
Shattered pellet injector systems have been installed on DIII-D, JET, and KSTAR used to experimentally determine the effectiveness of shattered injection (SPI) process in mitigating deleterious effects a tokamak plasma disruption. Pellets are fired, before entering plasma, strike bent tube known as shatter causing shatter. The fragmentation is chaotic that can be described terms fragment size distribution through statistical model incorporates material impact characteristics. In addition...
Erosion characteristics of tungsten-alternative plasma-facing materials (PFMs) were tested under high heat flux conditions in the electrothermal plasma source facility at Oak Ridge National Laboratory. The PFMs interest are high-purity β-3C chemical vapor deposition silicon carbide (SiC) and MAX phases Ti3SiC2 Ti2AlC [MAX = formula Mn+1AXn, where M is an early transition metal (such as Ti or Ta), A A-group element Si Al), X carbon nitrogen]. An erosion analysis method was developed using a...
Shattered pellet injection (SPI) has been chosen as the baseline disruption mitigation system on ITER due to its ability rapidly inject material deep into plasma greatly increase density and radiate thermal energy. SPI utilizes a mechanical punch or high-pressure gas release accelerate that cryogenically desublimated in barrel of pipe gun. Various combinations could possibly be implemented during different phases event energy, reduce electromagnetic loads machine components, avoid formation...
Reliably mitigating disruptions is essential for ITER to meet its long-term operational research plan without damage the in-vessel components. Currently, shattered pellet injection (SPI) technique most effective radiator of thermal energy and has been chosen baseline disruption mitigation system (DMS) ITER. The SPI process uses cryogenic temperatures desublimate material into barrel a pipe gun forming solid cylindrical pellet. Pellets will initially be hydrogen hydrogen–neon mixtures. Once...
A high-voltage pulsed power supply (HVPPS) has been designed, prototyped, and tested for driving an eddy current actuated propellant valve the International Thermonuclear Experimental Reactor (ITER) disruption mitigation system. The (HV) dc output voltage is software programmable, energy storage capacitor bank can be readily reconfigured as 200, 400, 600, 800 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math...
Mitigation of disruption events in future high energy density tokamaks is essential for machine longevity. The creation runaway electrons, large electromagnetic forces, and localized heat loads during a can be devastating to components. Shattered pellet injection currently the most effective method mitigation. Injection cryogenically solidified deuterium, neon, or argon (or mixtures thereof) have been shown efficiently radiate thermal plasma so that load distributed on walls machine. Pellets...
Cryogenic pellets are used for injection into fusion plasmas to add fuel build up density and replace the ions lost from reactions imperfect confinement in plasma. These formed at cryogenic temperatures with pure hydrogenic isotopes or mixtures of isotopes. Technology make these inject them has been under development many years, various methods using freezing desublimation have shown produce high-quality solid suitable injection. The throughput needed possible impurity content necessary...