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| 2. |
- Chen, Zhibin, et al.
(författare)
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Summary of the 3rd International Workshop on Gas-Dynamic Trap based Fusion Neutron Source (GDT-FNS)
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:6
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Tidskriftsartikel (refereegranskat)abstract
- The 3rd International Workshop on Gas-Dynamic Trap-based Fusion Neutron Source (GDT-FNS) was held through the hybrid mode on 13-14 September 2021 in Hefei, China, jointly organized by the Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS), and the Budker Institute of Nuclear Physics (BINP), Russian Academy of Sciences (RAS). It followed the 1st GDT-FNS Workshop held in November 2018 in Hefei, China, and the 2nd taking place in November 2019 in Novosibirsk, Russian Federation. With the financial support from CAS and China Association for Science and Technology (CAST), this workshop was attended by more than 80 participants representing 20 institutes and universities from seven countries, with oral presentations broadcast via the Zoom conferencing system. Twenty-two presentations were made with topics covering design and key technologies, simulation and experiments, steady-state operation, status of the ALIANCE project, multi applications of neutron sources, and other concepts (Tokamaks, Mirrors, FRC, Plasma Focus, etc). The workshop consensus was made including the establishment of the ALIANCE International Working Group. The next GDT-FNS workshop is planned to be held in May 2022 in Novosibirsk.
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| 3. |
- Coda, S., et al.
(författare)
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Physics research on the TCV tokamak facility: From conventional to alternative scenarios and beyond
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Tidskriftsartikel (refereegranskat)abstract
- The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, to exploratory plasmas driven by theoretical insight, exploiting the device's unique shaping capabilities. Disruption avoidance by real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic and radiation triggers. Runaway generation with high-Z noble-gas injection and runaway dissipation by subsequent Ne or Ar injection were studied for model validation. The new 1 MW neutral beam injector has expanded the parameter range, now encompassing ELMy H-modes in an ITER-like shape and nearly non-inductive H-mode discharges sustained by electron cyclotron and neutral beam current drive. In the H-mode, the pedestal pressure increases modestly with nitrogen seeding while fueling moves the density pedestal outwards, but the plasma stored energy is largely uncorrelated to either seeding or fueling. High fueling at high triangularity is key to accessing the attractive small edge-localized mode (type-II) regime. Turbulence is reduced in the core at negative triangularity, consistent with increased confinement and in accord with global gyrokinetic simulations. The geodesic acoustic mode, possibly coupled with avalanche events, has been linked with particle flow to the wall in diverted plasmas. Detachment, scrape-off layer transport, and turbulence were studied in L- and H-modes in both standard and alternative configurations (snowflake, super-X, and beyond). The detachment process is caused by power 'starvation' reducing the ionization source, with volume recombination playing only a minor role. Partial detachment in the H-mode is obtained with impurity seeding and has shown little dependence on flux expansion in standard single-null geometry. In the attached L-mode phase, increasing the outer connection length reduces the in-out heat-flow asymmetry. A doublet plasma, featuring an internal X-point, was achieved successfully, and a transport barrier was observed in the mantle just outside the internal separatrix. In the near future variable-configuration baffles and possibly divertor pumping will be introduced to investigate the effect of divertor closure on exhaust and performance, and 3.5 MW ECRH and 1 MW neutral beam injection heating will be added.
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| 4. |
- Hagnestål, Anders, et al.
(författare)
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A Compact Non-Planar Coil Design for the SFLM Hybrid
- 2012
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 31:4, s. 379-388
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Tidskriftsartikel (refereegranskat)abstract
- A non-planar single layer semiconductor coil set for a version of the Straight Field Line Mirror Hybrid concept with reduced magnetic field has been computed. The coil set consists of 30 coils that are somewhat similar to baseball coils with skewed sides. The coil set has been modeled with filamentary current distributions and basic scaling assumptions have been made regarding the coil widths. This coil set is expected to be considerably cheaper than a previous computed coil set. The coils can probably be produced with technologies known today.
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| 5. |
- Hagnestål, Anders, et al.
(författare)
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A study on field and coil designing for a quadrupolar mirror hybrid reactor
- 2011
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 30:2, s. 144-156
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Tidskriftsartikel (refereegranskat)abstract
- A vacuum magnetic field from a superconducting coil set for a single cell minimum B fusion-fission mirror machine reactor is computed. The magnetic field is first optimized for MHD flute stability, ellipticity and field smoothness in a long-thin approximation. Recirculation regions and magnetic expanders are added to the mirror machine without an optimizing procedure. The optimized field is thereafter reproduced by a set of circular and quadrupolar coils. The coils are modelled using filamentary line current distributions. Basic scaling assumptions are implemented for the coil design, with a maximum allowed current density of 1.5 kA/cm2. The coils are optimized using a local optimization method and the resulting field is checked for MHD flute stability and maximum ellipticity.
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| 6. |
- Hagnestål, Anders, 1976-
(författare)
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Coil Design and Related Studies for the Fusion-Fission Reactor Concept SFLM Hybrid
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A fusion-fission (hybrid) reactor is a combination of a fusion device and a subcritical fission reactor, where the fusion device acts as a neutron source and the power is mainly produced in the fission core. Hybrid reactors may be suitable for transmutation of transuranic isotopes in the spent nuclear fuel, due to the safety margin on criticality imposed by the subcritical fission core. The SFLM Hybrid project is a theoretical project that aims to point out the possibilities with steady-state mirror-based hybrid reactors. The quadrupolar magnetic mirror vacuum field is based on the Straight Field Line Mirror field and the central cell is 25 m long. A fission mantle surrounds the mirror cell. The fission to fusion power ratio is about 150 with keff = 0.97, implying that almost all the produced energy comes from fission. Beyond each mirror end magnetic expanders are located, which increase the plasma receiving “divertor” area and provide tolerable heat load on wall materials. The plasma is heated with ion cyclotron radio frequency heating and the fission mantle is cooled using a liquid lead-bismuth eutectic. The device is self-sufficient in tritium, and does not seem to suffer from severe material problems. A remaining issue may be the plasma electron temperature, which need to reach about 500 eV for efficient power production. In this doctoral thesis, theoretical work has been done with the magnetic coil system of such a device and also with the overall concept. A new coil type, the fishbone coil, suitable for single cell quadrupolar mirrors, has been invented. Two vacuum field coil sets with satisfying properties have been found, where the most recent coil set consists of fishbone coils. Finite ß effects on the magnetic field have been investigated, showing that the flux tube ellipticity increases with ß. The ellipticity of the vacuum field increases slightly with radius, but with finite ß it decreases with radius. The maximum flux surface radial extensions decrease with ß, which is an unexpected and beneficial result. A radial invariant has also been identified, and particle simulations have been made to emphasize that quadrupolar mirrors must be symmetric or confinement may be lost.
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| 7. |
- Hagnestål, Anders, et al.
(författare)
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Coil design for the straight field line mirror
- 2009
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 55:2T, s. 127-130
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Tidskriftsartikel (refereegranskat)abstract
- Coil systems for producing the Straight Field Line Mirror field using axisymmetric and quadrupolar coils are calculated. Two applications are intended, a fusion-fission nuclear waste transmutation device and a small plasma deposition device. Position, size and current for the axisymmetric coils are optimized as well as radial profile and current for the quadrupolar coils for the two applications. Calculations show that such a coil system can produce the Straight Field Line Mirror field for long-thin mirrors with moderate mirror ratio, but some other coil configuration needs to be found for mirrors where the coils cannot reside close to the plasma edge. In this work, the material science experiment mirror can be produced with about 1% error but the fusion-fission device field has not at this moment been reproduced with acceptable errors.
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| 8. |
- Hagnestål, Anders, et al.
(författare)
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Field and Coil Design for a Quadrupolar Mirror Hybrid Reactor
- 2011
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 30:2, s. 144-156
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Tidskriftsartikel (refereegranskat)abstract
- A vacuum magnetic field from a superconducting coil set for a single cell minimum B fusion-fission mirror machine reactor is computed. The magnetic field is first optimized for MHD flute stability, ellipticity and field smoothness in a long-thin approximation. Recirculation regions and magnetic expanders are added to the mirror machine without an optimizing procedure. The optimized field is thereafter reproduced by a set of circular and quadrupolar coils. The coils are modelled using filamentary line current distributions. Basic scaling assumptions are implemented for the coil design, with a maximum allowed current density of 1.5 kA/cm(2). The coils are optimized using a local optimization method and the resulting field is checked for MHD flute stability and maximum ellipticity.
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| 9. |
- Hagnestål, Anders, 1976-, et al.
(författare)
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Finite ß corrections to the magnetic field in the SFLM Hybrid
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Finite effects for the magnetic field in the SFLM Hybrid reactor concept have been studied numerically. The parallel current has been calculated, and it is found to be negligible. The constant pressure surfaces at the midplane are not significantly affected by the parallel current, and have a square-like octupolar distortion near the plasma edge. In most of the plasma region, their cross sections are nearly circular. The flux tube ellipticity is found to increase by the finite effects, but the increase is considerably more pronounced near the z axis where the pressure is high. At the plasma edge, the increase in ellipticity by finite effects is only moderate and the maximum radial extensions of the flux tube are even slightly decreased compared to the vacuum case.
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| 10. |
- Hagnestål, Anders, et al.
(författare)
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Radial Confinement in Non-Symmetric Quadrupolar Mirrors
- 2013
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Ingår i: Journal of fusion energy. - : Springer. - 0164-0313 .- 1572-9591. ; 32:3, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- Charged particles in symmetric quadrupolar mirrors are radially confined and have an associated radial invariant. In a symmetric quadrupolar field the magnetic field modulus satisfies B(z)=−B(z) along the axis if z = 0 defines the field minimum of the mirror, and the quadrupolar field has a corresponding symmetry. The field in the anchor cells of a tandem mirror need not obey a corresponding symmetry. In this paper, the radial confinement of non-symmetric mirrors is examined by tracing sample ions in the magnetic field. It is found that for non-symmetric mirrors, particles are typically not confined, and no radial invariant exists for such devices. Without attention to this effect in the field and coil design, radial confinement of trapped particles may be lost.
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