Physics of runaway electrons with shattered pellet injection at JET

2022 ◽  
Author(s):  
Cedric Reux ◽  
Carlos Paz-Soldan ◽  
Nicholas W. Eidietis ◽  
Michael Lehnen ◽  
Pavel Aleynikov ◽  
...  
Keyword(s):  
Gas Injection ◽  
Runaway Electrons ◽  
Large Area ◽  
Reliable Operation ◽  
Mhd Instability ◽  
Current Collapse ◽  
Pellet Injection ◽  
Heat Loads

Abstract Runaway electrons created during tokamak disruptions pose a threat to a reliable operation of future larger machines. Experiments using Shattered Pellet Injection (SPI) have been carried out at the JET tokamak to investigate ways to prevent their generation or suppress them if avoidance is not sufficient. Avoidance is possible if the SPI contains a sufficiently low fraction of high-Z material, or if it is fired early in advance of a disruption prone to runaway generation. These results are consistent with previous similar findings obtained with Massive Gas Injection. Suppression of an already accelerated beam is not efficient using High-Z material, but deuterium leads to harmless terminations without heat loads. This effect is the combination of a large MHD instability scattering runaway electrons on a large area and the absence of runaway regeneration during the subsequent current collapse thanks to the flushing of high-Z impurities from the runaway companion plasma. This effect also works in situations where the runaway beam moves upwards and undergoes scraping-off on the wall.

High pressure gas injection for suppression of runaway electrons in disruptions

2011 ◽  
Author(s):  
L.E. Zakharov ◽  
S. Putvinski ◽  
A.S. Kukushkin ◽  
R.A. Pitts ◽  
M. Sugihara ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Injection ◽  
Runaway Electrons

Comparison of disruption mitigation by shattered pellet injection to massive gas injection on J-TEXT

2021 ◽  
Author(s):  
You Li ◽  
Zhong yong Chen ◽  
Wei Yan ◽  
Yu Wei ◽  
Ruihai Tong ◽  
...  
Keyword(s):  
Gas Injection ◽  
Disruption Mitigation ◽  
Pellet Injection

scholarly journals Characteristics of Post-Disruption Runaway Electrons with Impurity Pellet Injection

2005 ◽  
Vol 81 (8) ◽  
pp. 593-601 ◽  
Author(s):  
Yasunori KAWANO ◽  
Tomohide NAKANO ◽  
Akihiko ISAYAMA ◽  
Nobuyuki ASAKURA ◽  
Hiroshi TAMAI ◽  
...  
Keyword(s):  
Runaway Electrons ◽  
Pellet Injection

scholarly journals Novel GIMS technique for deposition of colored Ti/TiO₂ coatings on industrial scale

2016 ◽  
Vol 34 (1) ◽  
pp. 137-141 ◽  
Author(s):  
Krzysztof Zdunek ◽  
Lukasz Skowroński ◽  
Rafal Chodun ◽  
Katarzyna Nowakowska-Langier ◽  
Andrzej Grabowski ◽  
...  
Keyword(s):  
Gas Injection ◽  
Deposition Process ◽  
Point Of View ◽  
Industrial Scale ◽  
Scale Production ◽  
Industrial Facility ◽  
Large Area ◽  
Glass Substrates ◽  
Process Measurements ◽  
20 Nm

AbstractThe aim of the present paper has been to verify the effectiveness and usefulness of a novel deposition process named GIMS (Gas Injection Magnetron Sputtering) used for the flrst time for deposition of Ti/TiO₂ coatings on large area glass Substrates covered in the condition of industrial scale production. The Ti/TiO₂ coatings were deposited in an industrial System utilizing a set of linear magnetrons with the length of 2400 mm each for covering the 2000 × 3000 mm glasses. Taking into account the speciflc course of the GIMS (multipoint gas injection along the magnetron length) and the scale of the industrial facility, the optical coating uniformity was the most important goal to check. The experiments on Ti/TiO₂ coatings deposited by the use of GIMS were conducted on Substrates in the form of glass plates located at the key points along the magnetrons and intentionally non-heated during any stage of the process. Measurements of the coatings properties showed that the thickness and optical uniformity of the 150 nm thick coatings deposited by GIMS in the industrial facility (the thickness differences on the large plates with 2000 mm width did not exceed 20 nm) is fully acceptable form the point of view of expected applications e.g. for architectural glazing.

Control System of Sand Milling Collection Machine Based on PLC

2014 ◽  
Vol 945-949 ◽  
pp. 2713-2720
Author(s):  
Zhong Kai Chen ◽  
Shi Qiu ◽  
Hao Hu ◽  
Ye Sun
Keyword(s):  
Control System ◽  
Local Control ◽  
Mining Engineering ◽  
Large Area ◽  
Reliable Operation ◽  
Long Distance ◽  
Wireless Control ◽  
Processing Cost ◽  
Depth Control ◽  
And Control

An engineering machine wireless control system is researched based on a diggings milling collection machine. The system consists of PLC, communications module, relays, touch screen, router and long-distance terminal. The ideas of PLC state of self-sustaining when host dropped, wireless control and local control redundancy, and control instructions prioritization are proposed to achieve the reliable operation of the system. The system with local control and wireless control has been applied on the sand milling collection machine and the wireless remote control of all operations has been realized with no instruction lost and misused. A mining engineering requires that the sand with the mine in the earth’s surface of about 2~5cm depth should be collected. Also, in order to realize the accurate collection to reduce the subsequent processing cost, it demands that the thick precision of the collection should be controlled within ±5mm. Considering that the milling collection is suitable for work of large-area sand collection and easier to meet the demand of the accurate control of the depth, the sand milling collection machine is researched. This machine is equipped with the milling collection unit and depth control system. It is able to conduct the sand collection experiment under the field condition.

scholarly journals Post-disruptive runaway electron beams in the COMPASS tokamak

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
Milos Vlainic ◽  
J. Mlynar ◽  
J. Cavalier ◽  
V. Weinzettl ◽  
R. Paprok ◽  
...  
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Gas Injection ◽  
Plasma Current ◽  
Runaway Electron Beam ◽  
Runaway Electrons ◽  
Current Ramp ◽  
Maximum Current ◽  
Current Value ◽  
Almost All

For ITER-relevant runaway electron studies, such as suppression, mitigation, termination and/or control of a runaway beam, it is important to obtain the runaway electrons after the disruption. In this paper we report on the first discharges achieved with a post-disruptive runaway electron beam, termed a ‘runaway plateau’, in the COMPASS tokamak. The runaway plateau is produced by a massive gas injection of argon. Almost all of the disruptions with runaway electron plateaus occurred during the plasma current ramp-up phase. The Ar injection discharges with and without a runaway plateau were compared for various parameters. Parametrisation of the discharges shows that the COMPASS disruptions fulfil the range of parameters important for runaway plateau occurrence. These parameters include electron density, electric field, disruption speed, effective safety factor, and the maximum current quench electric field. In addition to these typical parameters, the plasma current value just before the massive gas injection proved to be surprisingly important.

Erosion simulation of first wall beryllium armour after ITER transient heat loads and runaway electrons action

2011 ◽  
Vol 417 (1-3) ◽  
pp. 655-658 ◽  
Author(s):  
B. Bazylev ◽  
Yu. Igitkhanov ◽  
I. Landman ◽  
S. Pestchanyi ◽  
A. Loarte
Keyword(s):  
Runaway Electrons ◽  
First Wall ◽  
Heat Loads

scholarly journals Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

2015 ◽  
Vol 22 (10) ◽  
pp. 102506 ◽  
Author(s):  
E. M. Hollmann ◽  
N. Commaux ◽  
N. W. Eidietis ◽  
C. J. Lasnier ◽  
R. A. Moyer ◽  
...  
Keyword(s):  
Gas Injection ◽  
Vertical Displacement ◽  
Heat Loads

Convergent Beam Electron Diffraction

1978 ◽  
Vol 36 (3) ◽  
pp. 304-315
Author(s):  
G. Lehmpfuhl
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Crystal Surface ◽  
Diffraction Spot ◽  
Crystal Thickness ◽  
Large Area ◽  
Electron Microscopic ◽  
Additional Information ◽  
Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

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