| 1. |
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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
-
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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| 11. |
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| 12. |
- Hagnestål, Anders, et al.
(författare)
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Theoretical field and coil design for a single cell minimum-B mirror hybrid reactor
- 2011
-
Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 59:1T, s. 217-219
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Tidskriftsartikel (refereegranskat)abstract
- A vacuum magnetic field from a superconducting coil set for a single cell minimum-B mirror-based,fission-fusion reactor is computed. The magnetic field is optimized for MHD stability, ellipticity and field smoothness. A recirculation region and wide magnetic expanders on both sides are provided to the central mirror cell. A coil set producing this field is computed which consists of circular and quadrupolar coils. Basic scaling assumptions are made for the coil dimensions, based on a maximum allowed current density of 1.5 kA/cm(2) for superconducting coils. Sufficient space is available for a fission mantle. The field produced by the coils is checked for MHD plasma stability and maximum ellipticity. The resulting confinement region is 25 in long with a 40 cm midplane plasma radius.
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| 13. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 14. |
- Kovtun, Yurii, et al.
(författare)
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ICRF production of plasma with hydrogen minority in Uragan-2M stellarator by two-strap antenna
- 2024
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 31:4
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Tidskriftsartikel (refereegranskat)abstract
- The experiments on medium-size stellarator Uragan-2M (U-2M) in Kharkiv, Ukraine, are carried on in support of the Wendelstein 7-X (W7-X) experimental program. The scenario ion cyclotron frequency range (ICRF) plasma production at the hydrogen minority regime had been experimentally tested on U-2M and was qualified at the Large Helical Device (LHD). The paper presents the results of further research on the ICRF plasma production. The ICRF discharge studies were carried out in a H2 + He mixture with a controlled hydrogen concentration ranging from few percents to 75%. The two-strap like antenna mimicks the W7-X antenna operated in monopole phasing. The applied RF power was in the range of ∼100 kW. Relatively dense plasma of up to Ne ∼ 1019 m−3 was produced near the first harmonic of the hydrogen cyclotron frequency. The maximum temperature of the electrons and ions was not more than a few tens of electron volt. The characteristic features of RF plasma production and the propagation of electromagnetic waves in the experimental conditions are discussed. The experiments on U-2M and LHD indicate that the minority scenario of ICRF plasma production appears to be scalable and could be used in large stellarator machines. This is, in particular, important for the future experiments ICRF production of target plasma in W-7X in conditions where electron cyclotron resonance heating start-up is not possible.
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| 15. |
- Kovtun, Yurii V., et al.
(författare)
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ICRF plasma production at hydrogen minority regime in LHD
- 2023
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Ingår i: Nuclear Fusion. - : Institute of Physics Publishing (IOPP). - 0029-5515 .- 1741-4326. ; 63:10
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Tidskriftsartikel (refereegranskat)abstract
- This study aim is to develop further an ion cyclotron range of frequencies (ICRF) method of plasma production in stellarators based on the minority heating. The previous studies demonstrate production of low density plasma (9.5 × 1017m−3) at low power of up to 0.2 MW. The higher ICRF heating power experiments become possible after introducing a programmable ICRF power ramp up at the front of the ICRF pulse. With this trick, all the shots went with the antenna voltage within the safe range. Increase of the ICRF power predictably results in increase of the density of produced plasma. Without pre-ionization the plasma density achieved was 6 × 1018 m−3 which is 6 times higher than in previous experiments. However, the electron temperature was not high, the light impurities were hot fully stripped, and there were no recombination peaks after termination of the ICRF pulse. Plasma density is too low to provide good conditions for efficient plasma heating. For the reference, the ICRF heating of high density cold plasma prepared by electron cyclotron resonance heating is performed. Both electrons and ions were heated to high temperatures, and this plasma state is sustained. The antenna–plasma coupling was much better which result in larger heating power with the lower antenna voltage.
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| 16. |
- Kovtun, Yurii, V, et al.
(författare)
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ICRF Plasma Production with Hydrogen Minority Heating in Uragan-2M and Large Helical Device
- 2023
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Ingår i: Plasma and Fusion Research. - : Japan Society of Plasma Science and Nuclear Fusion Research. - 1880-6821. ; 18:2402042
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Tidskriftsartikel (refereegranskat)abstract
- This report compares results ion-cyclotron range of frequencies (ICRF) plasma production at hydrogen mi-nority regime in Uragan-2M (U-2M) and Large Helical Device (LHD). The condition of the presence of the fundamental harmonic ion cyclotron resonance zone for the hydrogen inside the plasma column should be ful-filled for this method. The scenario is successful at both machines and weakly sensitive to the variation of the hydrogen concentration in the H2+He gas mixture. It should be noted that at LHD the start up is slower than at U-2M. The comparison of plasma production in ICRF with hydrogen minority at U-2M and LHD indicate that this scenario can be scaled to larger stellarator devices. The experiments made are the base for the proposal for usage this scenario for plasma production in ICRF at Wendelstein 7-X at magnetic field reduced to 1.7 T.
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| 17. |
- Moiseenko, Vladimir E., et al.
(författare)
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A numerical model for radiofrequency heating of sloshing ions in a mirror trap
- 2006
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 72:6, s. 1133-1137
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Tidskriftsartikel (refereegranskat)abstract
- A newly developed numerical model calculating the distribution and damping of radiofrequency fields by sloshing ions is presented. The model solves time-harmonic Maxwell's equations written in terms of the electric field. It uses a two-dimensional grid and a Fourier series in the third coordinate and is based on a non-staggered mesh not aligned along the steady magnetic field. The numerical stability of the scheme is discussed, and the convergence analysis is presented.
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| 18. |
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| 19. |
- Moiseenko, Vladimir E., et al.
(författare)
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Fusion with fission power amplification
- 2008
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Ingår i: Problems of atomic science and technology. - 1562-6016. ; :6, s. 55-57
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Tidskriftsartikel (refereegranskat)abstract
- A scheme of a sub-critical system driven by fusion neutrons from a stellarator-mirror device is considered. In addition, a power production scheme which uses fusion power amplification by depleted uranium mantle is discussed.
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| 20. |
- Moiseenko, Vladimir E., et al.
(författare)
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Multiple recycle fuel cycle for spent nuclear fuel components incineration in fusion-fission hybrid
- 2022
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Ingår i: Problems of Atomic Science and Technology. - : Problems of Atomic Science and Technology. - 1562-6016. ; :6, s. 40-43
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Tidskriftsartikel (refereegranskat)abstract
- A multiple recycle fuel cycle (MRFC) is analyzed using a simple numerical model. A straightforward approach to MRFC has some unfavorable features like strong variation of the neutron multiplication factor and accumulation of americium isotopes which would likely hamper its practical usage. A solution proposed here is addition of 238U both to initial fuel and the recycled fuel.
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| 21. |
- Moiseenko, Vladimir E., et al.
(författare)
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Second harmonic ion cyclotron heating of sloshing ions in a straight field line mirror
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:2, s. 022503-
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Tidskriftsartikel (refereegranskat)abstract
- A qualitative analysis of second harmonic heating is carried out, in which a fast magnetosonic wave is launched from a location near the magnetic mirror (where the magnetic field is stronger than the second harmonic resonance field) and directed to the midplane of the open trap. The analysis shows that there is no "magnetic beach" heating in contrast to the case with minority heating on the fundamental harmonic. Conversion to the ion Bernstein wave would distort the heating pattern, and the condition for this conversion is estimated. The scenario of second harmonic heavy ion heating is examined numerically. In the scenario chosen, the regime of global resonance overlapping is achieved that provides good heating performance. The computations show that the power deposition is core, the amount of deposited power does not depend sensitively on the parameters of the discharge, and the range of plasma beta at which the heating is efficient is not narrow. The estimated antenna Q is noticeably low and, therefore, the antenna performance is high.
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| 22. |
- Moiseenko, Vladimir E., et al.
(författare)
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Stellarator-Mirror Based Fusion Driven Fission Reactor
- 2010
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 29:1, s. 65-69
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Tidskriftsartikel (refereegranskat)abstract
- The version of fusion driven system (FDS), a sub-critical fast fission assembly with a fusion plasma neutron source, theoretically investigated here is based on a stellarator with a small mirror part. In the magnetic well of the mirror part, fusion reactions occur from collision of an RF heated hot ion component (tritium), with high perpendicular energy with cold background plasma ions. The hot ions are assumed to be trapped in the magnetic mirror part. The stellarator part which connects to the mirror part provides confinement for the bulk (deuterium) plasma. Calculations based on a power balance analysis indicate the possibility to achieve a net electric power output with a compact FDS device. For representative thermal power output of a power plant (P th ≈ P fis = 0.5–2 GW) the computed electric Q-factor is in the range Q el = 8–14, which indicates high efficiency of the FDS scheme.
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| 23. |
- Moiseenko, Vladimir, et al.
(författare)
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Fast wave heating in a mirror during plasma build-up
- 2010
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Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 56:3, s. 359-367
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Tidskriftsartikel (refereegranskat)abstract
- A heating method for partially ionized plasma has been described in reference [V.E. Moiseenko, Sov. J. Plasma Phys. 12, 427 (1986)]. It exploits the collisional damping of fast waves that is large owing to the high rate of charge exchange collisions. Since the time of heating is limited by the duration of neutral gas ionization, the heating needs to be strong enough to achieve a high final ion temperature. This heating method has been studied numerically in the framework of MHD-like (magneto-hydrodynamic) equations in inhomogeneous cylindrical plasma. The influences of the ratio of the mean free path of the neutral atoms to the plasma radius, the initial ion concentration, the characteristics of the interaction of the neutral atoms with the chamber wall and other parameters on the plasma heating dynamics are examined. A scenario for RF plasma heating in one central cell of the multi-mirror device GOL3 (Novosibirsk, Russia) is developed, in which the final ion temperature exceeds the ion oscillation energy in the RF field by one order of magnitude. The energy efficiency is high; only a small portion of the power is transferred by the neutral atoms to the chamber wall.
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| 24. |
- Moiseenko, Vladimir, et al.
(författare)
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Radio-frequency heating in straight field line mirror neutron source
- 2011
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Konferensbidrag (refereegranskat)abstract
- There is a need in a practical scenario for ion heating up to high temperatures in a mirror based neutron source. Such a scenario could be developed with the ion cyclotron heating. Fundamental harmonic ion cyclotron heating of deuterium and second harmonic heating for tritium are studied numerically from the point of view of antenna coupling and heating efficiency. The behavior of the antenna loading resistance and radio-frequency power shine-through the cyclotron zone with the heating frequency, plasma density and temperature and the antenna position is analyzed.
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| 25. |
- Noack, Klaus, et al.
(författare)
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Neutronic model of a mirror based fusion-fission hybrid for the incineration of spent nuclear fuel and with potential for power generation
- 2011
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Konferensbidrag (refereegranskat)abstract
- In the last decade the Georgia Institute of Technology (Georgia Tech) published several design concepts of tokamak based fusion-fission hybrids which use solid fuel consisting of the transuranic elements of spent nuclear fuel from Light-Water-Reactors. The objectives of the hybrids are the incineration of the transuranic elements and additional net energy production. The paper presents a rough scientific design of the blanket of a mirror hybrid which was derived from the results of neutron transport calculations. The main operation parameters of two hybrid options were specified. One is the analog to Georgia Techs first version of a 'fusion transmutation of waste reactor" (FTWR) and the other is a possible near-term option which requires minimal fusion power.
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| 26. |
- Noack, Klaus, et al.
(författare)
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Neutronic model of a mirror based fusion-fission hybrid for the incineration of the transuranic elements from spent nuclear fuel and energy amplification
- 2011
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 38:2-3, s. 578-589
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Tidskriftsartikel (refereegranskat)abstract
- The Georgia Institute of Technology has developed several design concepts of tokamak based fusion-fission hybrids for the incineration of the transuranic elements of spent nuclear fuel from Light-Water-Reactors. The present paper presents a model of a mirror hybrid. Concerning its main operation parameters it is in several aspects analogous to the first tokamak based version of a "fusion transmutation of waste reactor". It was designed for a criticality keff <= 0.95 in normal operation state. Results of neutron transport calculations carried out with the MCNP5 code and with the JEFF-3.1 nuclear data library show that the hybrid generates a fission power of 3 GWth requiring a fusion power between 35 and 75 MW, has a tritium breeding ratio per cycle of TBRcycle = 1.9 and a first wall lifetime of 12-16 cycles of 311 effective full power days. Its total energy amplification factor was roughly estimated at 2.1. Special calculations showed that the blanket remains in a deep subcritical state in case of accidents causing partial or total voiding of the lead-bismuth eutectic coolant. Aiming at the reduction of the required fusion power, a near-term hybrid option was identified which is operated at higher criticality keff <= 0.97 and produces less fission power of 1.5 GWth. Its main performance parameters turn out substantially better.
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| 27. |
- Noack, Klaus, et al.
(författare)
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Safety And Power Multiplication Aspects Of Mirror Fusion-Fission Hybrids
- 2012
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Ingår i: Fusion for Neutrons and Subcritical Nuclear Fission. - : AIP. - 9780735410381 ; , s. 186-198
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Konferensbidrag (refereegranskat)abstract
- Recently, in a research project at Uppsala University a simplified neutronic model for a straight field line mirror hybrid has been devised and its most important operation parameters have been calculated under the constraints of a fission power production of 3 GW and that the effective multiplication factor k(eff) does not exceed 0.95. The model can be considered as representative for hybrids driven by other types of mirrors too. In order to reduce the demand on the fusion power of the mirror, a modified option of the hybrid has been considered that generates a reduced fission power of 1.5 GW with an increased maximal value k(eff) = 0.97. The present paper deals with nuclear safety aspects of this type of hybrids. It presents and discusses calculation results of reactivity effects as well as of driver effects.
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| 28. |
- Ågren, Olov, et al.
(författare)
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Coil design for the straight field line mirror
- 2022
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Ingår i: Problems of Atomic Science and Technology. - : Problems of Atomic Science and Technology. - 1562-6016. ; :6, s. 13-15
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Tidskriftsartikel (refereegranskat)abstract
- This paper briefly describes numerical design of 3D super-conduction coils aimed to mimic analytically derived magnetic field for the Straight Field Line Mirror (SFLM) concept. The paper is based on a manuscript for a previous IAEA report, i.e. IAEA-TECDOC-1998.
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| 29. |
- Ågren, Olov, et al.
(författare)
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Conceptual study of a straight field line mirror hybrid reactor
- 2011
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Ingår i: Problems of Atomic Science and Technology. - 1562-6016. ; :1, s. 3-7
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Tidskriftsartikel (refereegranskat)abstract
- A hybrid reactor based on the straight field line mirror (SFLM) with magnetic expanders at the ends is proposed as a compact device for transmutation of nuclear waste and power production. Compared to a fusion reactor, plasma confinement demands can be relaxed if there is a strong energy multiplication by the fission reactions, i.e. Q(r)=Pfission/Pfusion >> 1. The values of Q(r) is primarily restricted by fission reactor safety requirements. For the SFLM, computations suggest that values of Q(r) ranging up to 150 are consistent with reactor safety. In a mirror hybrid device with Q(r) > 100, the lower bound on the electron temperature for power production can then be estimated to be around 400 eV, which may be achievable for a mirror machine. The SFLM with its quadrupolar stabilizing fields does not rely on plasma flow into the expanders for MED stability, and a scenario with plasma density depletion in the expanders is a possibility to increase the electron temperature. Efficient power production is predicted with a fusion Q= 0.15 and an electron temperature around 500 eV. A fusion power of 10 MW could then be amplified to 1.5 GW fission power in a compact 25 m long hybrid mirror machine. Beneficial features are that all sensitive equipment can be located outside the neutron rich region and a steady state power production seems possible. Self circulation of the lead coolant, which is useful for heat removal if coolant pumps cease to operate, could be arranged by orienting the magnetic axis vertically. Results from studies on plasma equilibrium and stability, coil designing, RF heating and neutron computations are presented.
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| 30. |
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| 31. |
- Ågren, Olov, et al.
(författare)
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Fusion-fission hybrid reactor studies for the straight field line mirror
- 2011
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 59:1T, s. 166-169
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Tidskriftsartikel (refereegranskat)abstract
- A comparatively small mirror fusion hybrid device may be developed for industrial transmutation and energy production from spent nuclear waste. This opportunity ensues from the large fission to fusion energy multiplication ratio, Q(r) =P-fis/P-fus <= 150, in a subcritical fusion device surrounded by a fission mantle with the neutron multiplicity k(eff) approximate to 0.97. The geometry of mirror machines is almost perfectly suited for a hybrid reactor application, and the requirements for plasma confinement can be dramatically relaxed in correspondence with a high value of Q(r) Steady state power production in a mirror hybrid seems possible if the electron temperature reaches 500 eV. A moderately low fusion Q factor, the ratio of fusion power to the power necessary to sustain the plasma, could be sufficient, i.e. Q approximate to 0.15. Theoretical predictions for the straight field line mirror (SFLM) concept are presented, including results from radio frequency heating, neutron Monte Carlo and magnetic coil computations. Means to achieve an electron temperature of 500 eV are briefly discussed. The basic study considers a 25 m long confinement region with 40 cm plasma radius with 10 MW fusion power and a power production of 1.5 GW thermal.
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| 32. |
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| 33. |
- Ågren, Olov, et al.
(författare)
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Radial Drift Invariant in Long-Thin Mirrors
- 2012
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Ingår i: European Physical Journal D. - : Springer. - 1434-6060 .- 1434-6079. ; 66:28
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Tidskriftsartikel (refereegranskat)abstract
- In omnigenous systems, guiding centers are constrained to move on magnetic surfaces. Sincea magnetic surface is determined by a constant radial Clebsch coordinate, omnigeneity implies that theguiding center radial coordinate (the Clebsch coordinate) is a constant of motion. Near omnigeneity isprobably a requirement for high quality confinement and in such systems only small oscillatory radialbanana guiding center excursions from the average drift surface occur. The guiding center radial coordinateis then the leading term for a more precise radial drift invariant Ir, corrected by oscillatory “bananaripple” terms. An analytical expression for the radial invariant is derived for long-thin quadrupolar mirrorequilibria. The formula for the invariant is then used in a Vlasov distribution function. Comparisons arefirst made with Vlasov equilibria using the adiabatic parallel invariant. To model radial density profiles, itis necessary to use the radial invariant (the parallel invariant is insufficient for this). The results are alsocompared with a fluid approach. In several aspects, the fluid and Vlasov system with the radial invariantgive analogous predictions. One difference is that the parallel current associated with finite banana widths could be derived from the radial invariant.
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| 34. |
- Ågren, Olov, et al.
(författare)
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Studies of a Straight Field Line Mirror with emphasis on fusion-fission hybrids
- 2010
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 57:4, s. 326-334
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Tidskriftsartikel (refereegranskat)abstract
- The straight field line mirror (SFLM) field with magnetic expanders beyond the confinement region is proposed as a compact device for transmutation of nuclear waste and power production. A design with reactor safety and a large fission-to-fusion energy multiplication is analyzed. Power production is predicted with a fusion Q = 0.15 and an electron temperature of [approximately]500 eV. A fusion power of 10 MW may be amplified to 1.5 GW of fission power in a compact hybrid mirror machine. In the SFLM proposal, quadrupolar coils provide stabilization of the interchange mode, radio-frequency heating is aimed to produce a hot sloshing ion plasma, and magnetic coils are computed with an emphasis on minimizing holes in the fission blanket through which fusion neutrons could escape. Neutron calculations for the fission mantle show that nearly all fusion neutrons penetrate into the fission mantle. A scenario to increase the electron temperature with a strong ambipolar potential suggests that an electron temperature exceeding 1 keV could be reached with a modest density depletion by two orders in the expander. Such a density depletion is consistent with stabilization of the drift cyclotron loss cone mode.
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| 35. |
- Ågren, Olov, et al.
(författare)
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The straight field line mirror concept and applications
- 2008
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Ingår i: Problems of Atomic Science and Technology. - 1562-6016. ; :6, s. 8-12
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Tidskriftsartikel (refereegranskat)abstract
- The straight field line mirror field is a marginal minimum B field with straight nonparallel field lines. This field gives optimal ellipticity, the drift surfaces lie on a magnetic surface, radiofrequency heating of the plasma is predicted to be efficient and MHD stability is provided by the minimum B property. One intended application of the magnetic field configuration is energy production and transmutation of spent nuclear fuel in a fusion-fission machine, where the mirror confined plasma is surrounded by a fission mantle. Reactor safety can be increased with a subcritical fission mantle, and the fission power can exceed the fusion power by as much as a factor of 150 with a reasonable condition for reactor safety margins, and this provides a basis for a compact reactor design. The straight field line mirror concept can also be of interest as a plasma source for synthesis of sophisticated materials. PACS: 28.52.Av, 28.41.Ak.
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