Cryogenic Targets for Inertial Fusion Reactor
Development of a Facility for Producing the Reactor-Scaled Cryogenic Targets and Their Repeatable Assembly with Sabots
Tech Area / Field
- FUS-ICS/Inertial Confinement Systems/Fusion
3 Approved without Funding
FIAN Lebedev, Russia, Moscow
- State Enterprise Krasnaya Zvezda, Russia, Moscow\nSt Petersburg State Polytechnical University, Russia, St Petersburg
- General Atomics, USA, CA, San Diego\nOsaka University / Institute of Laser Engineering, Japan, Osaka\nENEA / ICF Physics and Technology Laboratory, Italy, Frascati\nGifu University, Japan, Gifu
Project summaryProject goal is the creation of a prototype of the facility that is capable of producing the reactor-scaled cryogenic targets, repeatable assembly of the unit “cryogenic target + sabot” and pre-acceleration of the assembly unit without target damage. Project completion will make possible the technically suitable solution for the key elements of the target factory.
From 2000 year, the inertial fusion energy (IFE) research has passed to a closeout stage aimed at creating a fusion reactor for electric power generation. An effective reactor operation requires that targets must be injected to the target chamber center at a rate of about 5 Hz. The target factory is of integral reactor part designed to providing the reactor with a required quantity of freestanding targets (500000 each day) and delivering them to the target injector. The key aspect of the target factory creation is elaboration of the efficient methods of cryogenic target production and building of the corresponding facility (further layering module).
Technologies based on using freestanding targets (FST) in each production step are the research area that has been intensively explored at the Lebedev Physical Institute (LPI). A prototypical system for the efficient production of cryogenic targets was accomplished at LPI in 1998 with the demonstration of filling, layering and delivering of millimeter size targets. Our achievements have made it possible to bring the FST technologies at the stage of extension on a reactor target design for IFE power plant. A careful assessment of the issue has shown that FST layering method is an emerging technology that meets the goal of repeatable target fabrication and injection. Currently, the repetition rate is about 0.1 Hz, which is caused by manual adjustment of the layering module. An experimental study of the target injection system at a repetition rate of several Hz is underway.
The integral part of IFE reactor is a target injector. Recently, a great deal of attention has been drawn on injector creation. At present, it is common knowledge that assembly of the target with a special sabot shall precede the target acceleration and injection. The functions of the sabot are as follows: (a) to transmit effectively acceleration impulse to the target, (b) to protect the target from damage caused by the overloads and heat transfer of the acceleration and injection processes.
Thus, the principle systems of the target factory are as follows:
1. layering module fabricating reactor-scaled cryogenic targets;
2. device for assembly of the unit “target + sabot” at cryogenic temperatures (working temperature < 18 К);
3. device for transporting the assembly unit to the injector (working temperature < 18 К).
Without these elements it is not possible for the fuel target injector and, consequently, for the reactor to function. Hence, absence of detailed engineering studies in the sphere of creation of the above devices may hamper for a long time implementation of the idea of energy generation due to IFE. Within the scope of this project it is proposed to develop the prototype facility incorporating all of the above devices.
The special approach to meet the Project goal is the creation of a prototype of facility, which is capable of:
- to form solid layer of fuel on the inner surface of a reactor-scaled polymer shells;
- to make the repeatable assembly of the unit “cryogenic target + sabot”;
- to pre-accelerate the unit to speeds of about 1-3 m/s with the object of its transport to the injector.
Within this scheme the prototype will operate with an array of freestanding shells (targets) at each stage of the production cycle that will minimize dead volume of fuel in the facility. The technologies dealing with freestanding targets developed in LPI for one-millimeter shells will be used as the basis for the prototype design.
The work aimed at prototype creation will proceed in three stages.
At stage 1 it is proposed to upgrade layering module available at LPI. New layering module will be designed for fabrication of classical high gain reactor targets consisting of 4 mm OD polymer shells with layer of solid fuel of 200 m thick on their inner surface. Formation of the fuel layer will be based on FST method.
At stage 2 the device for assembly of the unit “cryogenic target + sabot” will be developed.
Repetitive delivery of the targets from the collector into the revolver will proceed at cryogenic temperatures with the help of a shutter. It is expected that sabot pre-acceleration will take place under solenoidal field based on the same principles, which were used by us previously. This makes it possible to transport the assembly unit to the injector.
At stage 3 the elements of the facility prototype will be built up. A special test chamber will be constructed and connected to the prototype for the demonstration of its operation. At the inlet of the test chamber the sabot will be decelerated whereas the target will be injected into the chamber. For parameter characterization of the injected target it is proposed to develop the on-line diagnostics system.
An important feature of the technical approach is the ability of the layering module and of the assembly unit to operate as both standalone units and elements of the facility prototype.
Due to safety regulations, the work with the radioactive DT-mixture is prohibited on LPI premises. Hence, in this Project the use of D2-fuel only must be made. At the same time the ability of the created elements to subsequently use radioactive DT-fuel will be incorporated into the design of the facility prototype.
Scope of work.
In accordance with the technical approach, the main three tasks will be solved in the Project: (A) creation of the layering module for reactor-scaled targets, (B) development of the unit for «target + sabot» assembly, (C) integration of the created devices into a unified facility and sequential experimentation. The Project will be implemented based on the following program:
Task A. Creation of the layering module for reactor-scaled targets
A-1. Development of the technical specifications for the layering module (LM) with account for some target features and module-oriented capabilities to work as a standalone unit or as integral part of the assembly unit.
A-2. Design and manufacture of the layering module and associated equipment.
A-3. Theoretical study of the processes underlying the fuel layer formation by FST layering method in reactor-scaled targets.
A-4. Experimental study of the efficiency of fuel layer formation by FST layering method in reactor-scaled targets.
A-5. Layering module testing.
Task B. Development of the device for the unit «cryogenic target + sabot» assembly
B-1. Extensive studies of the thermal and mechanical loads on the cryogenic target in the process of assembly and pre-acceleration. Identification of the technical specifications for the assembly unit.
B-2. Sabot design.
B-3. Development of the diagnostic equipment to control the target parameters at the system outlet.
B-4. Design and manufacture of the elements of the device for assembly of the unit “cryogenic target + sabot” and of the test chamber.
B-5. Integration of the elements of the device for unit assembly. Device testing.
Task C. Devices Integration into a Unified Facility and Demonstration of the Facility Operation
C-1. Integration of the layering module, elements of the device for unit assembly, test chamber and diagnostic equipment into a unified facility.
C-2. Starting and testing facility operation over a closed cycle: formation assembly pre-acceleration.
C-3. Recommendations for integration of the created facility with the target injector and the laser system.
It is expected to accomplish the project for 3 years (36 months).
It is expected to arrive at the following results during the Project implementation:
- The results of reactor-scaled targets fabrication and their assembly with the sabots.
- The facility prototype and the results of its testing. The prototype includes the following components:
- Collector of cryogenic targets
- Set of sabots
- Unit for target & sabot assembly
- Extraction unit, including a coil and a guide channel
- Automatic control system synchronizing operation of all the prototype components
- Recommendations for the prototype assembly with target injector and laser system.
Prospects for application the project results
The facility created in the project forms the basis of innovative technology development for commercial application, namely - inexpensive mass production of IFE targets.
The facility created in the project can be also used for the optimization of major steps of the technological phase on a repeatable target delivery at the burn area of reactor.
Integration of the facility created in the project with a laser operated in the frequency range allows for the first time to create an operational model of the prototype reactor. The prototype-assisted research is the necessary stage under development the elements of a commercial reactor. Prof. T.Norimatsu noted in his supporting letter, «Success of the system operation will inspire young generation and help persuasion of suspicious people».
Potential foreign collaborators
General Atomics (USA), Institute of Laser Engineering, Osaka University (Japan) and the Faculty of Engineering, Gifu University (Japan) give their interest to be the project collaborators. It is planed that the foreign collaborators will participate in the Project in the scope of the following activities:
- Participation in development of the technical specifications of the key elements of prototype.
- Supply of the polymer shells to demonstrate the possibility of fabricating reactor-scaled targets by FST method.
- Participation in joint experiments.
- Joint reports and publications.
- Discussion of the results obtained and exchange of information of mutual interest.
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