Torus machine

For the elucidation of chemical reaction mechanisms, in-situ NMR spectroscopy is an established technique. For investigations at high pressure either sample tubes from sapphire [3] or metallic reactors [4] permitting high pressures and elevated temperatures are used. The latter represent autoclaves, typically machined from copper-beryllium or titanium-aluminum alloys. An earlier version thereof employs separate torus-shaped coils that are imbedded into these reactors permitting in-situ probing of the reactions within their interior. However, in this case certain drawbacks of this concept limit the filling factor of such NMR probes consequently, their sensitivity is relatively low, and so is their resolution. As a superior alternative, the metallic reactor itself may function as the resonator of the NMR probe, in which case no additional coils are required. In this way gas/liquid reactions or reactions within supercritical fluids can be studied... 

Perhaps the two most important implications of tritium inventory buildup in the torus are the locking up of the fuel in the PFMs (reducing the available fuel in the machine), and the need to keep the in-vessel T inventory within a licensed limit due to safety considerations. Based on postulated accident scenarios for ITER, the administrative in-vessel limit of mobilizable tritium has been set to be 1,000 g [2]. When the accumulated T inventory in the torus reaches this level, operation will have to be discontinued and dedicated T-removal procedures must be applied. 

It is evident that the removal of tritium from the torus of ITER-like machines requires the removal of tritium from the co-deposited layers, or perhaps - depending on the technique used - the removal of the co-deposits themselves. Notwithstanding the observation that tritium retention in short-pulse machines will be affected by mechanisms other than co-deposition, the experience gained from TFTR and JET - the only tritium-burning tokamaks in the world - is of paramount importance for gaining some understanding of the T-removal processes. Here we present a brief review of the T-removal experience with TFTR and JET, and then review controlled laboratory and... 

With careful planning, both TFTR and JET have demonstrated safe tritium handling in a fusion machine. Special controls imposed on the handling of tritium [60-62] have required that the quantity of tritium retained in the torus be accounted for and the inventory limited [63,64] in order to permit... 

He and He must be withdrawn. Up to now, this is done by shutting down, emptying the torus and filling it with a fresh D-T mixture. Suitable technical solutions for continuous operation of the machines have to be developed. 

For continuous cascade operation, the friction plate is lowered in the bowl so that a volume of material always remains inside while excess overflows. The residual volume can be either measured experimentally or calculated, assuming that the cross-section of the rope may be approximated by a fourth of a circle (quarter torus). To obtain a particular spheronization effect, an overall residence time must be maintained. The processing time in each machine can be calculated as the ratio of residual volume divided by the volumetric feed rate (= volumetric throughput). Since bowl diameters are predetermined and fixed by the design, the position of the friction plate in the bowl is the only variable which can be modified to match a certain feed rate or system capacity to the desired or necessary residence time. 

Figure 21.60 shows the schematic diagram of the KDS Micronex machine and the isometric sectional view of the torus. The KDS chamber encloses a set of eight spinning chains and a stationary torus above it. The chains are spun around in a horizontal plane by a motor-driven hub. The velocity at the chain tips is 200 m/s. The top of the torus is concave and its bottom is flat. Eight radially disposed baffle plates are welded at 120°C to the bottom surface of the torus. The blades provide a surface for the particles to impinge on, hence pulverize the product. In addition, the blades direct the peripheral air to the flow through the central hole of the torus. 

To make these membranes, a suitable phospholipid, lipid or mixture of lipids is dissolved in an organic solvent (say n-decane) the mixture is gently brushed across a circular orifice in a piece of machined teflon, which itself forms a partition between the two sides of a chamber filled with suitable electrolyte (say 0.1 M NaCl). The diameter of the orifice is usually 1 or 2 mm, and over a few seconds the lipid-containing solution thins down, the excess lipid remaining as a torus around the hole, until a black lipid bilayer remains covering the orifice and separating two salt solutions. 

In closed-ended machines the plasma is twisted back on itself to form a torus, eliminating the end-loss problem. Since simple toroidal magnetic fields do not confine plasma against radial outward drift, more complex magnetic field geometries are required in closed systems. Of the eight concepts, two, EBT and the Reversed-Field-Pinch, are closed systems, the others are open. 

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