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Helium-Cooled Divertor Target


Gas-Cooled Heat-Receiving Device Rated for High Steady-State Load for the Divertor of the Demonstration Fusion Reactor-Tokamak

Tech Area / Field

  • FUS-MCS/Magnetic Confinement Systems/Fusion

3 Approved without Funding

Registration date

Leading Institute
NIIEFA Efremov, Russia, St Petersburg


  • Sandia National Laboratories, USA, NM, Albuquerque\nGeneral Atomics, USA, CA, San Diego\nForschungszentrum Karlsruhe Technik und Umwelt / Institut fuer Reaktorsicherheit, Germany, Karlsruhe

Project summary

Divertor heat-receiving devices of plasma facilities working in the steady-state regime are usually cooled by water and meant for a heat load up to 10-20 MW/m2. But for safety reasons in a prospective fusion reactor water cannot be used to cool the plasma-facing components. Under these conditions a gas coolant is generally used at a typical heat load of about 5 MW/m2. At the outlet the coolant should have rather high temperature (no less than 400-700 °С) to improve the energy conversion and to attain an economically reasonable efficiency. High-pressure helium (no less than 10-15 MPa) has the most suitable thermophysical properties. Besides, rather stringent requirements are imposed on such a heat-receiving device in respect to reliability, lifetime, manufacturability, materials properties under irradiation, resistance to plasma erosion, etc. Therefore the development of the heat-receiving helium-cooled device meant for a steady-state load not less than 10-15 MW/m2 for the pertor of a demonstration tokamak-reactor is a highly complicated and urgent scientific and technical problem some aspects of which should be studied in the framework of this Project. The results of these studies can be applied in other technology areas where high-heat loads and gas convection are used. Besides, the results will be useful for creating the high-temperature gas-cooled reactor, which is considered at present one of the priority-driven direction of international scientific-technical co-operation.

Within the framework of the Project the design, calculation and experimental activities will be undertaken.

Design and calculation activities:

– Analysis of probable loads and operation conditions of the pertor of the DEMO tokamak-reactor.

– Analysis of the properties and selection of materials for all components of the pertor cassette (W, Mo, their alloys, copper and copper alloys, vanadium alloys, steels, including ferritic steels).
– Analysis of the data on material behavior under irradiation.
– Review and analysis of the known data on gas cooling, as applied to the plasma-facing units and components, as well as selection of the working gas parameters.
– Development and optimization of the pertor target design, selection of the geometry and dimensions of the protective armour, as well as cooling system.
– Thermal, gas-dynamic and thermomechanical analysis of the pertor plate module.
– More detailed calculation study of the peculiar features of gas dynamics and heat exchange at high gas flow rates, pressure and temperatures, search for the optimal channel configuration (jet cooling including). Elaboration of adapted calculation models and numerical codes.
– Analysis of the heat scheme parameters, thermal and operational reliability, the efficiency of energy conversion in the pertor cooling loop, feasibility study of the Project and cost estimation.

Optimization of technology and manufacturing of the main mock-up components:

– Optimization of the technology for shaping of the refractory protection armoring.

– Optimization of the technology for gas-tight joint of armoring materials with cooling tubes.
– Optimization of complicated channels profiling (refractory materials including).
– Manufacturing of mock-ups of the designed components.

Development and manufacturing of helium cooling loop for device testing:

– Development of the testing loop scheme, optimization of the loop parameters and components (for example, high-pressure compressor/blower, heat exchangers, pipelines, control instrumentation).

– Search for and selection of standard equipment, optimization of expenses.
– Development and manufacturing of the non-standard equipment for helium loop.
– Assembly of the loop, adjustment of the equipment, comprehensive tests and licensing.

Heat exchange experiments:

– Experimental study of the cooling efficiency in channels of various shapes, search for optimal configurations of ribs and turbolators, comparison of nozzles and slot channels.

– Experimental check of the results of the calculation of heat transfer, gas dynamics and other processes.

Life-time testing of the main heat-receiving device components:

– Tests for tightness when under the pressure (cold and hot, water and helium).

– Thermocycling of the mock-ups (Q=10-15 MW/m2, N=102-103).

Main parameters of the heat-receiving device and helium loop:

Maximum heat load on plate surface 15 MW/m2

Load mode cyclic with long pulses
Inlet helium temperature >300 °C
Inlet helium pressure 10-15 MPa
Helium pressure drop 0.5-1 MPa
Helium flow rate 100-600 g/s
Armour material of the device tungsten
Armour temperature range 1,000-2,000 °C
Total heat power of the modules 17-120 kW
Dimensions (effective diameter) of the module
on plasma-facing surface 20-40 mm
Number of modules 1-7

The above activities will make it possible to obtain data on operation conditions of gas-cooled heat-receiving devices at different cooling parameters. The results of the work can be used for design and manufacturing of various heat-receiving devices, namely, for fusion facilities with magnetic plasma confinement, target units of accelerating equipment, some components of non-nuclear energy and aerospace equipment. The results of the work will constitute a Russian contribution to the international cooperation in the framework of the DEMO fusion reactor. The works under the Project fall in the category of applied researches.

The Project has every reason to be successfully realized in view of the wide experience gained in the Scientific Technical Center SINTEZ in developing and investigating actively cooled high-heat flux components of fusion and other electrophysical facilities, in working with inert gases, gas recuperators, heat exchangers and heat-receiving devices. The available laboratory premises, testing (“Tsefey” e-beam facility) and technological (“Peklo” current-heating facility) electrophysical facilities, as well as the diagnostic equipment will provide the basis for the experiments under the Project. The experience of scientists and designers will be helpful in solving the theoretical problems of the Project.

It is assumed that the Project will essentially contribute to accomplishment of the ISTC objectives, namely:

– Keeping of highly qualified specialists involved in the Project.

– Promotion of conversion activities of the Project participating institutions.

Involvement of Russian scientists with previous weapon expertise in the international cooperation for peaceful purposes.


The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.


ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.

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