One of the remaining challenges in magnetic thermonuclear fusion is survival of the heat shield protecting the tokamak reactor vessel against excessive plasma heat fluxes. Unmitigated high confinement edge localized mode (ELM) is a regular heat pulse damaging the heat shield. We suggest a novel concept of magnetic sweeping of the plasma contact strike point fast and far enough in order to spread this heat pulse. We demonstrate feasibility of a dedicated copper coil in a resonant circuit, including the induced currents and power electronics. We predict the DEMO ELM properties, simulate heat conduction, 3D particles motion and magnetic fields of the plasma and coil in COMSOL Multiphysics and Matlab. The dominant system parameter is voltage, feasible 18 kV yields 1 kHz sweeping frequency, suppressing the ELM-induced surface temperature rise by a factor of 3. Multiplied by other known mitigation concepts, ELMs might be mitigated enough to ensure safe operation of DEMO.

ETH Zurich Switzerland

FEL Czech Technical University Technická 2 166 27 Prague Czech Republic

FNSPE Czech Technical University Břehová 7 115 19 Prague Czech Republic

Institute of Plasma Physics of the CAS Za Slovankou 3 182 00 Prague 8 Czech Republic

Zobrazit více v PubMed

Entler S, et al. Approximation of the economy of fusion energy. Energy. 2018;152:489–497. doi: 10.1016/j.energy.2018.03.130. DOI

European Research Roadmap to the Realisation of Fusion Energy www.euro-fusion.org/eurofusion/roadmap

Wenninger R, et al. The DEMO wall load challenge. Nucl. Fusion. 2017;57:046002. doi: 10.1088/1741-4326/aa4fb4. DOI

Maviglia F, et al. Impact of plasma thermal transients on the design of the EU DEMO first wall protection. Fus. Eng. Des. 2020;158:111713. doi: 10.1016/j.fusengdes.2020.111713. DOI

Barrett, T., et al. Progress in the engineering design and assessment of the European DEMO First Wall and Divertor Plasma Facing Components. EUROFUSION CP(15)06/13. https://scipub.euro-fusion.org/wp-content/uploads/2015/11/EFCP150613.pdf

https://financesonline.com/10-worlds-most-expensive-science-experiments/

https://www.iter.org/sci/Goals

Horacek J, et al. Scaling of L-mode heat flux for ITER and COMPASS-U divertors, based on five tokamaks. Nucl. Fusion. 2020;60:066016. doi: 10.1088/1741-4326/ab7e47. DOI

Sutton, G. P. & Biblarz O. Rocket propulsion elements (2017) 9th edition, Wiley, ISBN 9781118753910 https://www.vitalsource.com/products/rocket-propulsion-elements-george-p-sutton-oscar-v9781118753910

Ravensbergen T, et al. Real-time feedback control of the impurity emission front in tokamak divertor plasmas. Nat. Commun. 2021;12:1105. doi: 10.1038/s41467-021-21268-3. PubMed DOI PMC

Pitts RA, et al. Physics basis for the first ITER tungsten divertor. Mater. Energy. 2019;20:100696. doi: 10.1016/j.nme.2019.100696. DOI

Jiang M, et al. Inhibiting the Leidenfrost effect above 1000°C for sustained thermal cooling. Nature. 2022 doi: 10.1038/s41586-021-04307-3. PubMed DOI

Horacek J, et al. Predictive modelling of liquid metal divertor: From COMPASS tokamak towards Upgrade. Phys. Scr. 2021;96:124013. doi: 10.1088/1402-4896/ac1dc9. DOI

Panek R, et al. Conceptual design of the COMPASS upgrade tokamak. Fusion Eng. Des. 2017;123:11–16. doi: 10.1016/j.fusengdes.2017.03.002. DOI

Vondracek P, et al. Preliminary design of the COMPASS upgrade tokamak. Fusion Eng. Des. 2021;169:112490. doi: 10.1016/j.fusengdes.2021.112490. DOI

Weinzettl V, et al. Constraints on conceptual design of diagnostics for the high magnetic field COMPASS-U tokamak with hot walls. Fusion Eng. Des. 2019;146:1703–1707. doi: 10.1016/j.fusengdes.2019.03.020. DOI

Coda S, et al. Physics research on the TCV tokamak facility: From conventional to alternative scenarios and beyond. Nucl. Fusion. 2019;59:112023. doi: 10.1088/1741-4326/ab25cb. DOI

Reimerdes H, et al. Assessment of alternative divertor configurations as an exhaust solution for DEMO. Nucl. Fusion. 2020;60:066030. doi: 10.1088/1741-4326/ab8a6a. DOI

Loarte A. Chaos cuts ELMs down to size. Nat. Phys. 2006;2:369–370. doi: 10.1038/nphys331. DOI

Cruz N, et al. On the control system preparation for ELM pacing with vertical kicks experiments at TCV. Fusion Eng. Des. 2018;129:247–252. doi: 10.1016/j.fusengdes.2018.02.078. DOI

Evans T, et al. Edge stability and transport control with resonant magnetic perturbations in collisionless tokamak plasmas. Nat. Phys. 2006;2:10. doi: 10.1038/nphys312. DOI

Lennholm M, et al. Statistical assessment of ELM triggering by pellets on JET. Nucl. Fusion. 2021;61:036035. doi: 10.1088/1741-4326/abd861. DOI

Eich T, et al. ELM divertor peak energy fluence scaling to ITER with data from JET, MAST and ASDEX upgrade. Nuclear Mater. Energy. 2017;12:8490. doi: 10.1016/j.nme.2017.04.014. DOI

Adamek J, et al. Electron temperature and heat load measurements in the COMPASS divertor using the new system of probes. Nucl. Fusion. 2017;57:116017. doi: 10.1088/1741-4326/aa7e09. DOI

Suslova A, et al. Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples. Nat. Sci. Rep. 2014;4:6845. doi: 10.1038/srep06845. PubMed DOI PMC

Coenen J, et al. ELM induced tungsten melting and its impact on tokamak operation. J. Nuclear Mater. 2015;463:78–84. doi: 10.1016/j.jnucmat.2014.08.062. DOI

Coenen J, et al. ELM-induced transient tungsten melting in the JET divertor. Nucl. Fusion. 2015;55:023010. doi: 10.1088/0029-5515/55/2/023010. DOI

Kuang AQ, et al. Divertor heat flux challenge and mitigation in SPARC. J. Plasma Phys. 2020;86:865860505. doi: 10.1017/S0022377820001117. DOI

Maviglia F, et al. Impact of plasma-wall interaction and exhaust on the EU-DEMO design. Nuclear Mater. Energy. 2021;26:100897. doi: 10.1016/j.nme.2020.100897. DOI

M. Komm et al. Observations of ELM buffering in argon and nitrogen seeded discharges in AUG. Presentation at the 25th International Conference on Plasma Surface Interactions in Controlled Fusion Devices. https://www.psi2022.kr/program/program_02.html?searchTxt=komm

Gunn JP, et al. Ion orbit modelling of ELM heat loads on ITER divertor vertical targets. Nuclear Mater. Energy. 2017;12:75–83. doi: 10.1016/j.nme.2016.10.005. DOI

Arnoux G, et al. Thermal analysis of an exposed tungsten edge in the JET divertor. J. Nuclear Mater. 2015;463:415–419. doi: 10.1016/j.jnucmat.2014.11.005. DOI

Krieger K, et al. Investigation of transient melting of tungsten by ELMs in ASDEX upgrade. Phys. Scr. 2017;T170:014030. doi: 10.1088/1402-4896/aa8be8. DOI

Silvagni D, et al. I-mode pedestal relaxation events at ASDEX Upgrade. Nucl. Fusion. 2020;60:126028. doi: 10.1088/1741-4326/abb423. DOI

Horacek J, et al. Plans for liquid metal divertor in tokamak compass. Plasma Phys. Rep. 2018;44(7):652–656. doi: 10.1134/S1063780X18070024. DOI

Horacek J, et al. Modeling of COMPASS tokamak divertor liquid metal experiments. Nuclear Mater. Energy. 2020;25:100860. doi: 10.1016/j.nme.2020.100860. DOI

Kallenbach A, et al. Developments towards an ELM-free pedestal radiative cooling scenario using noble gas seeding in ASDEX Upgrade. Nuclear Fusion. 2021;61:016002. doi: 10.1088/1741-4326/abbba0. DOI

Jacquinot J, et al. Deuterium-tritium operation in magnetic confinement experiments: Results and underlying physics. Plasma Phys. Control. Fusion. 1999;41:A13–A46. doi: 10.1088/0741-3335/41/3A/002. DOI

Romanelli F, et al. Overview of the JET results with the ITER-like wall. Nucl. Fusion. 2013;53:104002. doi: 10.1088/0029-5515/53/10/104002. DOI

Clery D, et al. European fusion reactor sets record for sustained energy. Science. 2022;375(6581):600. doi: 10.1126/science.ada1089. PubMed DOI

Putterich T, et al. Calculation and experimental test of the cooling factor of tungsten. Nucl. Fusion. 2010;50:025012. doi: 10.1088/0029-5515/50/2/025012. DOI

Wang Shuming, et al. Thermal damage of tungsten-armored plasma-facing components under high heat flux loads. Nat. Sci. Rep. 2020;10:1359. doi: 10.1038/s41598-020-57852-8. PubMed DOI PMC

Horacek J, et al. Feasibility study of fast swept divertor strike point suppressing transient heat fluxes in big tokamaks. Fusion Eng. Des. 2017;123:646–649. doi: 10.1016/j.fusengdes.2017.01.027. DOI

Li M, Maviglia F, Federici G, You J-H. Sweeping heat flux loads on divertor targets: Thermal benefits and structural impacts. Fusion Eng. Des. 2016;102:50–58. doi: 10.1016/j.fusengdes.2015.11.026. DOI

Lukes, S. Horacek, J. Fast swept divertor suppressing transient heat pulses in tokamaks. Master Thesis, Czech Technical University (2022). https://dspace.cvut.cz/handle/10467/100839

You JH, et al. Progress in the initial design activities for the European DEMO divertor: Subproject “Cassette”. Fusion Eng. Des. 2017;124:364370. doi: 10.1016/j.fusengdes.2017.03.018. DOI

Pitts RA, et al. Physics conclusions in support of ITER W divertor monoblock shaping. Mater. Energy. 2017;12:60–74. doi: 10.1016/j.nme.2017.03.005. DOI

Gunn JP, et al. Surface heat loads on the ITER divertor vertical targets. Nucl. Fusion. 2017;57:046025. doi: 10.1088/1741-4326/aa5e2a. DOI

https://en.m.wikipedia.org/wiki/Solenoid

DEMO Eurofusion private document. https://idm.euro-fusion.org

Adamek J, et al. On the transport of edge localized mode filaments in the tokamak scrape-off layer. Nuclear Fusion. 2020;60:096014. doi: 10.1088/1741-4326/ab9e14. DOI

Hamalainen H, et al. AC resistance factor of Litz-Wire windings used in low-voltage high-power generators. IEEE Trans. Ind. Electron. 2014;61(2):693–700. doi: 10.1109/TIE.2013.2251735. DOI

Gaudreau, M. et al Solid-state power systems for pulsed electric field (PEF) processing. In 2005 IEEE Pulsed Power Conference Solid-State Power Systems for Pulsed Electric Field (PEF) Processing. 10.1109/PPC.2005.300605

Fridman B, et al. A 0.5-MJ 18-kV module of capacitive energy storage. IEEE Trans. Plasma Sci. 2011;39:769. doi: 10.1109/TPS.2010.2095430. DOI

Ma K, et al. Evaluation and design tools for the reliability of wind power converter system. J. Power Electron. 2015;15(5):1149–1157. doi: 10.6113/JPE.2015.15.5.1149. DOI

Becoulet M, et al. Screening of resonant magnetic perturbations by flows in tokamaks. Nucl. Fusion. 2012;52:054003. doi: 10.1088/0029-5515/52/5/054003. DOI

Dejarnac R, et al. Overview of COMPASS tokamak divertor liquid metal experiments. Nuclear Mater. Energy. 2020;25:100801. doi: 10.1016/j.nme.2020.100801. DOI