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Description
The Divertor Tokamak Test (DTT) facility (https://www.dtt-project.it/), currently in initial phase of construction at the ENEA Frascati Research Center, is designed to explore critical components of tokamak, such as the divertor, in plasma regimes that are relevant for ITER and DEMO (as far as power loads are concerned), and where plasma core and edge properties are fully integrated. To achieve this goal, considerable amounts of additional power will be injected in DTT, whose ambitious program is spread over several years with different operational phases. During the initial plasma operations (phase 1) 3 MW of ICRH, 14.5 MW of ECRH, and 7.5 MW of NNBI will be available. Additional power, up to a total of 45 MW, will be afterwards installed, on the basis of the results of Phase 1 and of technologies that will be available at that time. Moreover, in order to be relevant for DEMO, the DTT facility is designed to produce sufficiently long plasma pulses, thus requiring the adoption of a superconducting magnet system.
DTT magnet system includes 18 Toroidal Field (TF) coils, 6 Central Solenoid (CS) modules and 6 poloidal Field (PF) coils. All superconducting coils are supported by a cold structure with thermalized gravity supports and thermally protected in a cryostat with actively cooled thermal shields. The coils and their structures need to be cooled by supercritical helium supplied at about 4.3 K. The thermal shields have to be cooled with a circulation of pressurised helium between 80 K and 100 K. The superconducting coils are connected to the power supply by means of superconducting feeders which need to be maintained at 4.3K. High Temperature Superconducting (HTS) current leads, which operate between ambient and cryogenic temperatures, require cold helium gas flow at 50 K. To allow helium and hydrogen adsorption, cryopumps behind the divertor targets require 2 cryogenic helium streams, one at 4.3K for the cryopump panels and one at 80K for cryopump baffles.
The Cryogenic System has to cool-down the cryogenic users and keep them at their design temperatures during different operation modes and plasma scenarios. The overall cryogenic capacity is estimated around 11 kW equivalent power at 4.5K.
This paper gives a general overview of the cryogenic system requirements, the conceptual design, the layout and a description of the main components such as: the Helium Compression Station (HCS), the Warm Gas Storage (WGS), a Refrigerator Cold Box (RCB), an Auxiliary Cold Box (ACB), the Main CryoLine (MCL), the Cryogenic Valve Boxes (CVB) and the cryodistribution to the final users.
| Submitters Country | Italy |
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