| 1. |
- Chernitskiy, S. V., et al.
(författare)
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Neutronic Model of a Stellarator-Mirror Fusion-Fission Hybrid
- 2013
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 63:1T, s. 322-324
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Tidskriftsartikel (refereegranskat)abstract
- The MCNPX numerical code has been used to model the neutron transport in a mirror based fusion-fission reactor. The purpose is to find a principal design of the fission mantle which fits to the neutron source and to calculate the leakage of neutrons through the mantle surface of the fission reactor. The fission reactor part has a cylindrical shape with an outer radius 1.66 m and a 4 m length. The fuel has the isotopic composition of the spent nuclear fuel from PWR after uranium-238 removal. Inside the fission reactor core is a vacuum chamber with a radius 0.5 m containing a 4 m long hot plasma producing fusion neutrons. To sustain the hot ion plasma which is responsible for the fusion neutron production, neutral beam injection is considered. Calculation results for the radial leakage of neutrons through the mantle surface of the fission reactor are presented. These calculations predict that the power released with neutrons from the reactor to outer space would be small and will not exceed the value of 6 kW while the reactor thermal power is 1 GWth.
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| 2. |
- Coad, J. P., et al.
(författare)
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Distribution of hydrogen isotopes, carbon and beryllium on in-vessel surfaces in the various jet divertors
- 2005
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 48:1, s. 551-556
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Tidskriftsartikel (refereegranskat)abstract
- JET has operated with divertors of differing geometries since 1994. Impurities accumulated in the inner leg of all the divertors, and operation of the first (Mk I) divertor with beryllium tiles demonstrated that most are eroded from the main chamber walls and swept along the scrape-off layer to the inner divertor. Carbon deposited at the inner divertor is then locally transported to shadowed regions such as the inner louvres, where, for example, most of the tritium was trapped during the deuterium-tritium experiment (DTE1). Factors affecting these transport processes (e.g. temperature) are important for ITER, but are not well understood.
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| 3. |
- Coelho, R., et al.
(författare)
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Synthetic Diagnostics In The European Union Integrated Tokamak Modelling Simulation Platform
- 2013
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 63:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The European Union Integrated Tokamak Modelling Task Force (ITM-TF) has developed a standardized platform and an integrated modeling suite of codes for the simulation and prediction of a complete plasma discharge in any tokamak. The framework developed by ITM-TF allows for the development of sophisticated integrated simulations (workflows) for physics application, e.g., free-boundary equilibrium with feedback control, magnetohydrodynamic stability analysis, core/edge plasma transport, and heating and current drive. A significant effort is also under way to integrate synthetic diagnostic modules in the ITM-TF environment, namely, focusing on three-dimensional reflectometry, motional Stark effect, and neutron and neutral particle analyzer diagnostics. This paper gives an overview of the conceptual design of ITM-TF and preliminary results of the aforementioned synthetic diagnostic modules.
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| 4. |
- Cufar, Aljaz, et al.
(författare)
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Calculations to Support In Situ Neutron Yield Calibrations at the Joint European Torus
- 2018
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Ingår i: Fusion science and technology. - : Informa UK Limited. - 1536-1055 .- 1943-7641. ; 74:4, s. 370-386
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Tidskriftsartikel (refereegranskat)abstract
- The fusion power output of fusion plasmas is measured using the neutron yield detectors due to its linear relation to the fusion yield. Absolutely calibrated neutron yield detectors are thus a crucial part of the plasma diagnostics system and the absolute accuracy of their calibration must be ensured. The transition of the Joint European Torus's (JET's) first wall material from carbon (C) wall to ITER-like (Be/W/C) first wall was a significant change in the structure of the machine and recalibration of the main neutron yield detectors was needed to maintain the required measurement uncertainty of less than +/- 10%. The neutron yield detectors were thus recalibrated through two in situ calibrations to deuterium-deuterium neutrons in 2013 and deuterium-tritium neutrons in 2017 using 252Cf spontaneous fission source and a compact neutron generator, respectively. We describe the extensive neutronics calculations performed in support of these latest calibration experiments. These analyses were performed using Monte Carlo simulations to better understand the calibration procedure, optimize the experiments, ensure personnel safety, and quantify the effects of the uncharacteristic circumstances during calibration experiments. This paper focuses on assessments of the effects of the uncharacteristic circumstances, e. g., the presence of the remote handling system in the machine due to its use in neutron source delivery, difference in the neutron emission spectrum, and differences in the neutron source shape. Lessons learned, findings, and relevance for calibrations of future large tokamaks are discussed.
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| 5. |
- Donné, Adam, et al.
(författare)
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Overview of core diagnostics for TEXTOR
- 2005
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 47:2, s. 220-245
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Tidskriftsartikel (refereegranskat)abstract
- The diagnostic system of TEXTOR comprises about 50 individual diagnostic devices. Since the start of the Trilateral Euregio Cluster collaboration, part of the emphasis in the experimental program has shifted toward the study of physics processes in the plasma core. To aid these studies several new and advanced core diagnostics have been implemented, whereas a number of other core diagnostics have been upgraded to higher resolution, more channels, and better accuracy. In this paper a brief overview is given of the present set of plasma core diagnostics at TEXTOR.
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| 6. |
- Ferreira, Diogo R., et al.
(författare)
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Full-Pulse Tomographic Reconstruction with Deep Neural Networks
- 2018
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Ingår i: Fusion science and technology. - : TAYLOR & FRANCIS INC. - 1536-1055 .- 1943-7641. ; 74:1-2, s. 47-56
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Tidskriftsartikel (refereegranskat)abstract
- Plasma tomography consists of reconstructing a two-dimensional radiation profile of a poloidal cross section of a fusion device based on line-integrated measurements along several lines of sight. The reconstruction process is computationally intensive, and in practice, only a few reconstructions are usually computed per pulse. In this work, we trained a deep neural network based on a large collection of sample tomograms that have been produced at JET over several years. Once trained, the network is able to reproduce those results with high accuracy. More importantly, it can compute all the tomographic reconstructions for a given pulse in just a few seconds. This makes it possible to visualize several phenomena-such as plasma heating, disruptions, and impurity transport-over the course of the entire pulse.
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| 7. |
- Giegerich, Thomas, et al.
(författare)
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Conceptual design of the mechanical tritium pumping system for jet DTE2
- 2015
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Ingår i: Fusion science and technology. - : TAYLOR & FRANCIS INC. - 1536-1055 .- 1943-7641. ; 68:3, s. 630-634
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the conceptual design of the Mechanical Tritium Pumping System (MTPS) that shall be installed and tested at JET during the next Deuterium-Tritium-Experiment (DTE2). This pump train uses a two-stage liquid ring pump in combination with a booster pump to cover a pressure regime from 10(-1) Pa to 10(5) Pa. As working fluid for all pumps, mercury will be used for tritium compatibility reasons. Starting from the requirements to MTPS, the pumps and their arrangement will be described in this paper as well as the mercury containment strategy and safety- and control issues.
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| 8. |
- Graves, J. P., et al.
(författare)
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RECENT ADVANCES IN SAWTOOTH CONTROL
- 2011
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 59:3, s. 539-548
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Tidskriftsartikel (refereegranskat)abstract
- Important advances have been made recently in the invention and application of experimental methods to control the sawtooth instability in tokamak plasmas. The primary means of control involves the application of either ion cyclotron resonance heating (ICRH), or electron cyclotron heating, with resonance very close to the q = 1 radius in the plasma core. Reported here are experiments that have successfully applied these methods to either shorten or lengthen the sawteeth deliberately, in a variety of plasma conditions, in three tokamaks: Joint European Torus (JET), TCV, and Tore Supra. It is shown that despite the sensitivity of the sawtooth period to the resonance position, sawteeth can be controlled using either real-time control of the electron cyclotron deposition, or in the case of ion cyclotron heating, very careful adjustment of the magnetic field strength and minority ion concentration. The latter technique has been guided by theoretical advances that have enabled the control of sawteeth in JET with ITER-relevant ICRH scenarios.
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| 9. |
- 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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| 10. |
- Hagnestål, Anders, et al.
(författare)
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Theoretical field and coil design for a single cell minimum-B mirror hybrid reactor
- 2011
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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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