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Lunt T, Bernert M, Brida D, David P, Faitsch M, Pan O, Stieglitz D, Stroth U, Redl A. Compact Radiative Divertor Experiments at ASDEX Upgrade and Their Consequences for a Reactor. PHYSICAL REVIEW LETTERS 2023; 130:145102. [PMID: 37084430 DOI: 10.1103/physrevlett.130.145102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 03/02/2023] [Indexed: 05/03/2023]
Abstract
We present a novel concept to tackle the power exhaust challenge of a magnetically confined fusion plasma. It relies on the prior establishment of an X-point radiator that dissipates a large fraction of the exhaust power before it reaches the divertor targets. Despite the spatial proximity of the magnetic X point to the confinement region, this singularity is far away from the hot fusion plasma in magnetic coordinates and therefore allows the coexistence of a cold and dense plasma with a high potential to radiate. In the compact radiative divertor (CRD) the target plates are placed close to this magnetic X point. We here report on high performance experiments in the ASDEX Upgrade tokamak that indicate the feasibility of this concept. Despite the shallow (projected) field line incidence angles of the order of θ_{⊥}=0.2°, no hot spots were observed on the target surface monitored by an IR camera, even at a maximum heating power of P_{heat}=15 MW. And even with the X point located exactly on the target surface and without density or impurity feedback control, the discharge remains stable, the confinement good (H_{98,y2}=1), hot spots absent, and the divertor in a detached state. In addition to its technical simplicity, the CRD scales beneficially to reactor-scale plasmas that would benefit from an increased volume of the confined plasma, more space for breeding blankets, smaller poloidal field coil currents, and-potentially-an increased vertical stability.
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Affiliation(s)
- T Lunt
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - M Bernert
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - D Brida
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - P David
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - M Faitsch
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - O Pan
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - D Stieglitz
- Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - U Stroth
- Physik-Department E28, Technische Universität München, 85747 Garching, Germany and Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching, Germany
| | - A Redl
- Universitá degli Studi della Tuscia, DEIM, 01100 Viterbo, Italy
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Federici F, Reinke ML, Lipschultz B, Thornton AJ, Harrison JR, Lovell JJ, Bernert M. Design and implementation of a prototype infrared video bolometer (IRVB) in MAST Upgrade. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:033502. [PMID: 37012791 DOI: 10.1063/5.0128768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/23/2023] [Indexed: 06/19/2023]
Abstract
A prototype infrared video bolometer (IRVB) was successfully deployed in the Mega Ampere Spherical Tokamak Upgrade (MAST Upgrade or MAST-U), the first deployment of such a diagnostic in a spherical tokamak. The IRVB was designed to study the radiation around the lower x-point, another first in tokamaks, and has the potential to estimate emissivity profiles with spatial resolution beyond what is achievable with resistive bolometry. The system was fully characterized prior to installation on MAST-U, and the results are summarized here. After installation, it was verified that the actual measurement geometry in the tokamak qualitatively matches the design; this is a particularly difficult process for bolometers and was done using specific features of the plasma itself. The installed IRVB measurements are consistent both with observations from other diagnostics, including magnetic reconstruction, visible light cameras, and resistive bolometry, as well as with the IRVB-designed view. Early results show that with conventional divertor geometry and only intrinsic impurities (for example, C and He), the progression of radiative detachment follows a similar path to that observed for large aspect ratio tokamaks: The peak of the radiation moves along the separatrix from the targets to the x-point and high-field side midplane with a toroidally symmetric structure that can eventually lead to strong effects on the core plasma inside the separatrix.
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Affiliation(s)
- Fabio Federici
- York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | | | - Bruce Lipschultz
- York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Andrew J Thornton
- United Kingdom Atomic Energy Authority, Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
| | - James R Harrison
- United Kingdom Atomic Energy Authority, Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
| | - Jack J Lovell
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Matthias Bernert
- Max Planck Institute for Plasma Physics, EURATOM Association, D-85748 Garching, Germany
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Muscente P, Innocente P, Ball J, Gorno S. Analysis of edge transport in L-mode negative triangularity TCV discharges. NUCLEAR MATERIALS AND ENERGY 2023. [DOI: 10.1016/j.nme.2023.101386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Harrer GF, Faitsch M, Radovanovic L, Wolfrum E, Albert C, Cathey A, Cavedon M, Dunne M, Eich T, Fischer R, Griener M, Hoelzl M, Labit B, Meyer H, Aumayr F. Quasicontinuous Exhaust Scenario for a Fusion Reactor: The Renaissance of Small Edge Localized Modes. PHYSICAL REVIEW LETTERS 2022; 129:165001. [PMID: 36306746 DOI: 10.1103/physrevlett.129.165001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 07/08/2022] [Accepted: 08/08/2022] [Indexed: 06/16/2023]
Abstract
Tokamak operational regimes with small edge localized modes (ELMs) could be a solution to the problem of large transient heat loads in fusion reactors. A ballooning mode near the last closed flux surface governed by the pressure gradient and the magnetic shear there has been proposed for small ELMs. In this Letter, we experimentally investigate several stabilizing effects near the last closed flux surface and present linear ideal simulations that indeed develop ballooninglike fluctuations there and connect them with nonlinear resistive simulations. The dimensionless parameters of the small ELM regime in the region of interest are very similar to those in a reactor, making this regime the ideal exhaust scenario for a future device.
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Affiliation(s)
- G F Harrer
- Institute of Applied Physics, TU Wien, Fusion@ÖAW, Vienna, Austria
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - M Faitsch
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - L Radovanovic
- Institute of Applied Physics, TU Wien, Fusion@ÖAW, Vienna, Austria
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - E Wolfrum
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - C Albert
- Institute of Theoretical and Computational Physics, TU Graz, Graz, Austria
| | - A Cathey
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - M Cavedon
- Dipartimento di Fisica "G. Occhialini," Università di Milano-Bicocca, Milano, Italy
| | - M Dunne
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - T Eich
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - R Fischer
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - M Griener
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - M Hoelzl
- Max Planck Institute for Plasma Physics, Garching, Germany
| | - B Labit
- École Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland
| | - H Meyer
- CCFE, Culham Science Centre, Abingdon, Oxon, United Kingdom
| | - F Aumayr
- Institute of Applied Physics, TU Wien, Fusion@ÖAW, Vienna, Austria
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Lunt T, Bernert M, Brida D, Cavedon M, David P, Faitsch M, Feng Y, Griener M, Herrmann A, Kurzan B, Pan O, Plank U, Silvagni D, Teschke M, Willensdorfer M, Wischmeier M, Wolfrum E, Zammuto I. Study of detachment in future ASDEX Upgrade alternative divertor configurations by means of EMC3-EIRENE. NUCLEAR MATERIALS AND ENERGY 2021. [DOI: 10.1016/j.nme.2021.100950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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