1,721,116 research outputs found
Compact tokamak neutron sources as a first step towards hybrid fission-fusion reactors
No full textAn Ignitor-like tokamak that is compact, high field, and high density device, could make full use of the its intense neutron flux, without reaching ignition as a source of neutrons for materials testing in support of a fission-fusion hybrid device. The main features of this High Field Neutron Source Facility, which would have about 50% more plasma volume than Ignitor, are illustrated and the R&D required in order to achieve relevant dpa quantities in test materials are discussed. Several full-power months of operation are sufficient to obtain relevant radiation damage values in terms of dpa, and a scoping study of shielding the magnetic insulators to reduce radiation damage has been performed
THz-TDS Transmission Measurements of Spectroscopic Lamps Plasma
No full textWe will discuss the transmission spectra of plasmas generated by spectroscopic lamps filled with different gas compounds. The spectral response is measured with a standard THz-TDS spectrometer with 2 THz bandwidth. © 2018 IEEE
The tilted-coil concept for advanced tokamak devices
Full text linkIn questo rapporto si studiano gli effetti conseguenti all’inclinazione in direzione azimutale dei magneti toroidali di un tokamak. Il principale vantaggio consiste in una drastica riduzione delle forze elettromagnetiche. Un vantaggio ausiliario consiste nella generazione di campo poloidale, che si va ad aggiungere a quello toroidale. La riduzione delle forze permette una notevole semplificazione del progetto della macchina, mentre il flusso poloidale generato durante la crescita della corrente, se usato in serie con il flusso indotto dal solenoide centrale, permette di estendere la durata delle scariche rispetto al caso di un tokamak con magneti toroidali convenzionali.The implications of the adoption of a tokamak’s toroidal field coil characterized by tilting in the azimuthal direction are investigated. The major advantage introduced by tilted coils is that of a drastic reduction over most of the coil section of the electromagnetic forces. As a beneficial side-effect, the tilted coils generate a poloidal field, in addition to the toroidal field. The former advantage allows for a notable simplification of the machine layout, while the poloidal flux generated during the current rise, when used in conjunction with the conventional central solenoid, allows for discharges of much longer duration with respect to those obtainable in tokamaks with conventional (non-tilted legs)
coils
Modelling of the Ignitor scrape-off layer including neutrals
No full textIgnitor is a tokamak project aimed at achieving ignition. In the reference scenario, plasma-surface interactions are controlled by a Mo first-wall/limiter, which constitutes a simple engineering solution but, at the same time, a special challenge for edge plasma modelling. Here the ASPOEL plasma fluid code, already applied to Ignitor in the recent past, is coupled with the neutral Monte Carlo code EIRENE. We study the effects of the neutrals on the plasma density and temperature profiles in the Ignitor scrape-off layer, and compute the particle and heat loads onto the Ignitor first-wall limiter
Compact tokamaks as convenient neutron sources for hybrid reactors
No full textThe foreseen future expansion of nuclear power
would involve a solution to burn the long half-life
transuranics (TRU) in the spent nuclear fuel discharged
from LWRs. Moreover, high-energy neutrons can be very
useful for many processes. The study addresses the
development of a tokamak neutron source for a hybrid
fission-fusion demonstration experimental device, using
Ignitor-based technologies. Ignitor is a proposed compact
high magnetic field tokamak, aimed at reaching ignition
in DT plasmas. A revision of its operating parameters, in
order to act a as a suitable neutron source in a hybrid
device, is discussed, and a new operating scenario is
proposed. Features of the tokamak neutron source are
illustrated and preliminary results are discussed. A two phase
project is described, in order to test an Ignitor-based
neutron source and then implement an
experimental device for demonstration of technical
feasibility of TRU transmutation
Ignitor-like Toroidal Devices for Neutron Production
No full textCompact fusion toroidal machines operating in DT have the potential to become efficient sources of neutrons for material testing. An Ignitor-like device could be envisaged for this purpose, making full use of the intense neutron flux that it can generate without reaching ignition. Preliminary radiation damage estimates for some fusion-relevant materials have shown that few full-power months of operation would provide adequate dpa levels. The main features and technological issues of a High Field Neutron Source Facility based on the Columbus concept, with about 50% more volume than Ignitor, are illustrated and discussed. Optimization of the plasma temperature and density relative to the reference ignition scenario (with the assistance of auxiliary heating power) can achieve considerable reductions of duty cycle requirements. The constraints imposed by flux availability, magnet heating and wall loading will inevitably impose a complete redesign of the machine, with the adoption of novel materials (such as MgB2 superconductor already adopted for Ignitor), and new modes of operation will need be investigate
Compact Tokamak Neutron Sources As A First Step Towards Hybrid Fission-Fusion Reactors
No full textAn Ignitor-like tokamak that is compact, high field, and high density device, could make full use of the its intense neutron flux, without reaching ignition as a source of neutrons for materials testing in support of a fission-fusion hybrid device. The main features of this High Field Neutron Source Facility, which would have about 50% more plasma volume than Ignitor, are illustrated and the R&D required in order to achieve relevant dpa quantities in test materials are discussed. Several full-power months of operation are sufficient to obtain relevant radiation damage values in terms of dpa, and a scoping study of shielding the magnetic insulators to reduce radiation damage has been performe
Plasma Welll Interaction Physics in Ignitor
No full textThe introduction of a proper divertor in meaningful fusion burn experiments is at times advocated with the argument that it addresses the rcactor relevant issue of ash and impurity control and it allows easier access to the H-mode regime. On the other hand, a divettor decreases the volume available for the plasnna and introduces structutes that have to withstand high thermal wall loadings and the effects of disruptions in a high magnetic field environment. Other related questions are whether the density profiles that characterize the H-regime, for which a divertor is introduced, are optimal for ignition, whether the divertor has indeed led to cleaner core plasmas than those produced in limiter devices , and whether other means to remove the alfa-particles produced by fusion reactions, e.g. during their slowing down, are more appropriate even in principle. In the Ignitor operating scenario of reference, ignition can be reached by ohmic heating only. The edge conditions are characterized by relatively low temperatures and high densities. In high density regimes , an extensive series of experiments has observed a low level of impurity in the plasma core, thanks to both reduced sputtering from the wall and improved screening properties of the adjacent plasma. Radiation losses gain importance in dissipating the power leaving the main plasma and the whole scrape off layer contributes in dispersing the energy of the particles impinging on the material walls, even without the introduction of additional impurities. Therefore, the extended limiter solution, with the plasma wetting a large fraction of the first wall surface, has been preferred over that of a traditional divertor configuration
The differentially-tilted toroidal field coil concept for tokamaks
Full text linkThe implications of the adoption of a tokamak's toroidal field coil characterized by differential tilting in the azimuthal direction are investigated. From an engineering point of view, the major advantage introduced by such coils is a drastic reduction of some components of the electromagnetic forces in certain areas. As a beneficial side-effect, they generate poloidal field, in addition to toroidal field. The former advantage allows for a partial relaxation of the reinforcing structural material required in the machine design, while the poloidal flux generated during the current rise, when used in conjunction with the conventional central solenoid, would allow for discharges of longer duration. This paper presents results obtained by applying the tilting optimization procedure to circular and D-shaped coils, and characterized by geometrical and physical parameters proper of high-field compact tokamaks, since the issue of electromagnetic force reduction is most relevant in these devices
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