Design and material issues for high performance SiCf/SiC-based fusion power cores

2001 ◽  
Vol 55 (1) ◽  
pp. 55-95 ◽  
Author(s):  
A.R Raffray ◽  
R Jones ◽  
G Aiello ◽  
M Billone ◽  
L Giancarli ◽  
...  
1998 ◽  
Vol 258-263 ◽  
pp. 65-73 ◽  
Author(s):  
D.L Smith ◽  
M.C Billone ◽  
S Majumdar ◽  
R.F Mattas ◽  
D.-K Sze

2019 ◽  
Vol 26 ◽  
pp. 144
Author(s):  
T. Vasilopoulou ◽  
M. I. Savva ◽  
I. Michelakaki ◽  
K. Triantou ◽  
K. Mergia ◽  
...  

The intense collaborative effort for electricity generation through fusion is currently focused on the exploitation of the Joint European Torus (JET) as well as on the preparation of its successors ITER and DEMO. Within this frame, several experiments are carried out at JET aiming to study crucial aspects related to the construction and operation of ITER as well as to the design of future fusion power plants.Most important, a high-performance Deuterium-Tritium campaign is expected to take place at JET in 2020 providing unique neutron yields up to 1.7×1021 neutrons. This paper focuses on the participation of NCSRD fusion technology group in JET nuclear analysis and, in particular, on the implementation of activation experiments at JET and discusses the main achievements in the light of their significance for optimizing future fusion activities and studies.


Author(s):  
A. E. Costley

The question of size of a tokamak fusion reactor is central to current fusion research especially with the large device, ITER, under construction and even larger DEMO reactors under initial engineering design. In this paper, the question of size is addressed initially from a physics perspective. It is shown that in addition to size, field and plasma shape are important too, and shape can be a significant factor. For a spherical tokamak (ST), the elongated shape leads to significant reductions in major radius and/or field for comparable fusion performance. Further, it is shown that when the density limit is taken into account, the relationship between fusion power and fusion gain is almost independent of size, implying that relatively small, high performance reactors should be possible. In order to realize a small, high performance fusion module based on the ST, feasible solutions to several key technical challenges must be developed. These are identified and possible design solutions outlined. The results of the physics, technical and engineering studies are integrated using the Tokamak Energy system code, and the results of a scoping study are reviewed. The results indicate that a relatively small ST using high temperature superconductor magnets should be feasible and may provide an alternative, possibly faster, ‘small modular’ route to fusion power. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.


MRS Bulletin ◽  
1989 ◽  
Vol 14 (7) ◽  
pp. 48-52 ◽  
Author(s):  
Dale L. Smith

The next major step in the development of fusion power involves the design, construction, and operation of an experimental power reactor. The general objective of this type of device is to demonstrate key plasma physics, materials, and engineering performance under conditions that approach those considered necessary to establish the technical feasibility of fusion power. This device is generally perceived to be a tokamak configuration that operates on the deuterium-tritium (D-T) fuel cycle, which would produce several hundred megawatts of fusion power. Although a number of conceptual design studies on this type of device have been conducted, the current effort is focused on the International Thermonuclear Experimental Reactor (ITER) activity, a joint undertaking of the European Community (EC), Japan, the United States, and the Soviet Union, conducted under the auspices of the International Atomic Energy Agency (IAEA).The development of fusion power as an energy source depends to a large extent on the proper selection of materials for the various components. these materials will be exposed to a wide variety of conditions such as plasma particle and neutron radiation, high thermal fluxes, large thermal and mechanical stress, various chemical environments, and high magnetic fields. In order to achieve the high performance desired for a commercial power reactor, considerable materials development will be required. Because of the relatively near term time scale projected for ITER and the limited objectives, more conventional materials with more extensive data bases will be used where possible. Even so, a substantial materials development program is required to support a test reactor like ITER.


Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).


Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.


Author(s):  
John W. Coleman

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.


Author(s):  
J W Steeds ◽  
R Vincent

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.


Author(s):  
Klaus-Ruediger Peters

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).


Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.


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