東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Disruption Mitigation in Tokamaks wi...

Vallhagen, Oskar.

Linked to FindBook

Google Book

Amazon

博客來

Disruption Mitigation in Tokamaks with Massive Material Injection.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Disruption Mitigation in Tokamaks with Massive Material Injection./
Author:	Vallhagen, Oskar.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
Description:	59 p.
Notes:	Source: Masters Abstracts International, Volume: 85-01.
Contained By:	Masters Abstracts International85-01.
Subject:	Plasma. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30518622
ISBN:	9798379871147

Disruption Mitigation in Tokamaks with Massive Material Injection.
Vallhagen, Oskar.

Disruption Mitigation in Tokamaks with Massive Material Injection. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 59 p.

Source: Masters Abstracts International, Volume: 85-01.

Thesis (Licentiate)--Chalmers Tekniska Hogskola (Sweden), 2023.

This item must not be sold to any third party vendors.

The sudden loss of confinement of the energy content of fusion plasmas in off-normal events. called disruptions. is among the most severe threats to the future of fusion energy based on the tokamak design. An efficient disruption mitigation system will therefore be of utmost importance for future large. high-current devices such as ITER. The potentially greatest threat to be mitigated is posed by currents carried by highly energetic electrons, called runaway electrons. which may cause severe damage upon wall impact. The disruption mitigation system must also ensure a sufficiently homogeneous deposition of the thermal energy on the plasma-facing components. and avoid excessive forces on the machine due to currents flowing in the surround- ing structures. The currently envisaged mitigation method is to initiate a massive material injection. e.g. in the form of a pressurized gas or a shattered cryogenic pellet. when an emerging disruption is detected. and so attempt to better control the plasma cooling and energy dissipation.In this thesis, we develop modeling tools for the various physical phenomena present during a tokamak disruption mitigated by a massive materia] injection. This includes extending the numerical tools GO and DREAM with the capability to handle more advanced geometry. effects of partial ionization in the cooling plasma on the generation of runaway electrons. and the material assimilation in the plasma following a shattered pellet injection. These tools are then used to perform inte- grated numerical simulations, assessing the mitigation performance for a wide range of injection scenarios in reactor-scale tokamak devices. Finally. we also develop an analytical model for the radial transport of the relatively cold and dense material recently ablated from a shattered pellet upon exposure to the hot plasma.Our results indicate that the severity of a disruption in a reactor-scale device can be significantly reduced by a carefully chosen injection scheme and composition of the injected material. In particular. a two-stage shattered pellet injection might efficiently reduce the localised heat loads and the runaway generation due to the hot- tail mechanism. by allowing for an intermediate equilibration of the superthermal electron population between the injections. However. the strong runaway avalanche associated with a high plasma current was found to be able to amplify even a very small runaway seed. such as those produced by tritium decay and Compton scattering during nuclear operation. to several mega-amperes. The reason is that the intense cooling from the injected material leads to a high induced electric field and a substantial recombination. resulting in an enhanced avalanche multiplication. Our calculations also indicate that this mitigation scheme might be further complicated by a relatively large outward drift of the recently ablated pellet material.

ISBN: 9798379871147Subjects--Topical Terms:

877619
Plasma.

Disruption Mitigation in Tokamaks with Massive Material Injection.
LDR:04046nmm a2200373 4500 001 2396380
005 20240611104237.5
006 m o d
007 cr#unu||||||||
008 251215s2023 ||||||||||||||||| ||eng d
020 $a 9798379871147
035 $a (MiAaPQ)AAI30518622
035 $a (MiAaPQ)Chalmers_SE535522
035 $a AAI30518622
040 $a MiAaPQ $c MiAaPQ
100 1 $a Vallhagen, Oskar. $3 3766071
245 1 0 $a Disruption Mitigation in Tokamaks with Massive Material Injection.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2023
300 $a 59 p.
500 $a Source: Masters Abstracts International, Volume: 85-01.
500 $a Advisor: Fulop, Tunde.
502 $a Thesis (Licentiate)--Chalmers Tekniska Hogskola (Sweden), 2023.
506 $a This item must not be sold to any third party vendors.
520 $a The sudden loss of confinement of the energy content of fusion plasmas in off-normal events. called disruptions. is among the most severe threats to the future of fusion energy based on the tokamak design. An efficient disruption mitigation system will therefore be of utmost importance for future large. high-current devices such as ITER. The potentially greatest threat to be mitigated is posed by currents carried by highly energetic electrons, called runaway electrons. which may cause severe damage upon wall impact. The disruption mitigation system must also ensure a sufficiently homogeneous deposition of the thermal energy on the plasma-facing components. and avoid excessive forces on the machine due to currents flowing in the surround- ing structures. The currently envisaged mitigation method is to initiate a massive material injection. e.g. in the form of a pressurized gas or a shattered cryogenic pellet. when an emerging disruption is detected. and so attempt to better control the plasma cooling and energy dissipation.In this thesis, we develop modeling tools for the various physical phenomena present during a tokamak disruption mitigated by a massive materia] injection. This includes extending the numerical tools GO and DREAM with the capability to handle more advanced geometry. effects of partial ionization in the cooling plasma on the generation of runaway electrons. and the material assimilation in the plasma following a shattered pellet injection. These tools are then used to perform inte- grated numerical simulations, assessing the mitigation performance for a wide range of injection scenarios in reactor-scale tokamak devices. Finally. we also develop an analytical model for the radial transport of the relatively cold and dense material recently ablated from a shattered pellet upon exposure to the hot plasma.Our results indicate that the severity of a disruption in a reactor-scale device can be significantly reduced by a carefully chosen injection scheme and composition of the injected material. In particular. a two-stage shattered pellet injection might efficiently reduce the localised heat loads and the runaway generation due to the hot- tail mechanism. by allowing for an intermediate equilibration of the superthermal electron population between the injections. However. the strong runaway avalanche associated with a high plasma current was found to be able to amplify even a very small runaway seed. such as those produced by tritium decay and Compton scattering during nuclear operation. to several mega-amperes. The reason is that the intense cooling from the injected material leads to a high induced electric field and a substantial recombination. resulting in an enhanced avalanche multiplication. Our calculations also indicate that this mitigation scheme might be further complicated by a relatively large outward drift of the recently ablated pellet material.
590 $a School code: 0419.
650 4 $a Plasma. $3 877619
650 4 $a Physics. $3 516296
650 4 $a Cooling. $3 1457878
650 4 $a Thermal energy. $3 3560700
650 4 $a Gases. $3 559387
650 4 $a Charged particles. $3 3682557
650 4 $a Heat. $3 573595
650 4 $a Alternative energy sources. $3 3561089
650 4 $a Energy resources. $3 3561090
650 4 $a Fusion. $3 3380818
650 4 $a Energy consumption. $3 631630
650 4 $a Radiation. $3 673904
650 4 $a Power plants. $3 3564814
650 4 $a Alternative energy. $3 3436775
650 4 $a Atomic physics. $3 3173870
650 4 $a Energy. $3 876794
650 4 $a Plasma physics. $3 3175417
690 $a 0605
690 $a 0363
690 $a 0748
690 $a 0791
690 $a 0759
710 2 $a Chalmers Tekniska Hogskola (Sweden). $3 1913472
773 0 $t Masters Abstracts International $g 85-01.
790 $a 0419
791 $a Licentiate
792 $a 2023
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30518622