The aim of the Ignitor tokamak is to achieve plasma fusion ignition conditions by ohmic heating—inducing a current in the plasma flow in the direction of the toroidal current without the involvement of powerful additional heating. A tokamak is a reactor designed to control nuclear fusion in a plasma of ions and electrons inside a doughnut-shaped, or toroidal, magnetic bottle. The name ‘tokamak’ is derived from the Russian acronym for a ‘toroidal magnetic chamber’.
Achieving the required value of the toroidal plasma current to provide an ohmic heating to thermonuclear temperatures requires the use of strong magnetic fields, more than 2-4 times larger than the toroidal and poloidal magnetic field in conventional tokamaks. The increased magnetic fields can retain a higher plasma kinetic pressure and, consequently, a higher plasma density. The 10-fold growth of the specific density of the plasma increases the relative yield of thermonuclear reactions by 100 times, which in turn makes it possible to significantly reduce the size of the tokamak, while maintaining the integrated energy output. The essence of the Ignitor project is to create a tokamak with strong magnetic fields and a strong toroidal current.
Experiments on the ignition of thermonuclear reactions mainly from ohmic heating of dense plasma in high power-density tokamaks with a strong magnetic field will significantly simplify the technology and reduce the cost of power fusion reactors.
Reactors of this type will be:
- More compact, because they will work with plasma that is ten times as dense as other tokamaks
- Free of complicated and expensive auxiliary heating systems such as injectors, neutrals, gyrotrons and high-frequency, high-power systems
- Optimised with a simple technological process management software
- More reliable and efficient due to reducing the complexity of systems in the reactor
- Lower capital costs than other tokamaks.
History
Ignitor’s predecessors are the Alcator tokamak (MIT, USA), and a Soviet-era unit proposed by academics EP Velikhov and BB Kadomtsev with a strong field (TSP).
The TSP Tokamak was the first operating tokamak with a strong toroidal field (13 T), designed to achieve conditions in which the power of fusion reactions exceeds the power expended in heating the plasma.
A TSP experiment was set up at the Troitsk research centre near Moscow and a tokamak manufactured and put into operation in 1987. Unfortunately the disintegration of the Soviet Union and as a consequence, the termination of the financing programme caused this to be suspended.
The first contact between Ignitor project collaborators EP Velikhov and MIT physicist Bruno Coppi took place in 2004. Velikhov proposed using the unique capabilities of the TSP tokamak complex at a Troitsk research institute. After contact with the Italian government in 2005, Coppi began to promote the project to Italy’s ministry of industry and innovation. At the time Silvio Berlusconi’s government supported the establishment of the Ignitor project in Russia. Information about the funding is not available at this stage, but costs are expected to be shared equally between the two countries.
Like the TSP tokamak, the Ignitor tokamak will use a strong toroidal field (13 T). But unlike it, the Ignitor tokamak will not use adiabatic compression to heat plasma to thermonuclear temperatures, but instead use the strong current. An auxiliary heating system involving the injection of RF power is also included in the Ignitor design.
Preliminary features
The Tokamak electromagnetic system is made from copper or magnesium diboride cooled to a temperature of 30 K. Large electromagnetical and thermomechanical systems and the selection of appropriate structural materials can withstand the stresses associated with the large reaction. A central solenoid with a strong field (more than 14 T) is used for the excitation current. Fuel pellets are injected at high speed (more than 4 km/sec) to increase the plasma density. All electromagnetic components are placed in a cryostat and cooled by helium gas. The final temperature is an optimal ratio of electrical conductivity of pure copper (or MgB2) to its specific heat.
Requirements for successful performance of the Ignitor project include:
- Experimental hall with biological protection constructed of non-magnetic steels in the zone of strong magnetic fields, as well as secure and powerful ventilation
- A power supply system that can provide the required toroidal and poloidal fields, the flux in the central solenoid, and plasma field control
- A cryogenic system that provides cooling of the electromagnetic system and can maintain it at a temperature of 30 K
- A blanket system and recovery system for tritium and tritium-containing products
- A modern management and protection system
- Physical and technological diagnostics to monitor and control the plasma column
- Laboratory and office space for supporting works and project staff accommodation.
The Troitsk facility
The Strong Field Tokamak (TSP) site’s existing energy, experimental bench base and infrastructure mean that the site best satisfies these technical requirements and the starting conditions for the project. The research centre was originally the USSR magnet laboratory (1952-61); a division of the Kurchatov Institute of Atomic Energy (1961-1991), and then the Troitsk Institute for Innovation and Fusion Research (1991-1993). Since then, it has been the State Research Centre of Russian Federation Troitsk Institute for Innovation and Fusion Research. The Troitsk site, 18km from Moscow, employs 35,000 people in 12 research institutes, including SRC RF TRINITI.
TSP has 1220 employees, including two members of the Russian Academy of Sciences, 20 professors, 55 DScs, 150 PhD candidates, and a doctoral dissertation council in plasma physics and laser physics. The site includes one of three operating Russian T-11M tokamaks; the Angara-5 TW-term electrical generator, an MK-200 plasma accelerator, and an energy complex.
The power supply system provides static power of 330 MW from the grid and surges of up to 1000 MW for up to 100 seconds from four surge turbogenerators. In addition, other SRC RF TRINITI energy complex functions include:
- Electrical substation with 80MW power
- Inductive storage with an energy content of 1 GJ
- 3 surge generators (TCD-200) with a power of 200 MW
- Pulsed power up to 10GW from a capacitor bank with energy content 10MJ
- Cooling tower and cooling system
- Tritium system
- Experimental hall with biosecurity and ventilation system.
Tokamak T-11M, the Department of Physics tokamak reactor, employs 140 skilled workers. The total area of the facility is 80,000 sq m, which includes building 220 (experimental assembly halls, laboratories and support facilities), and buildings 201, 215, 216 and 217 to accommodate the surge generators.
Many tasks remain to prepare the centre for the Ignitor project. The centre needs to:
- Raise the installed capacity of the transformer substation to the desired value
- Complete and start up the fourth surge generator 216
- Inspect, repair and start up the three existing generators 201, 215 and 217
- Renovate the TSP cryogenic system
- Inspect and repair the complex cooling system
- Resolve issues related to the conduct of tritium experiments in the Moscow region
- Modernize infrastructure
- Conduct Ignitor preparatory works (design, fuel injection system, operational training, diagnostics and data acquisition and processing system)
- Manage works on the campus to provide access in accordance with established procedure
- Build a residential complex in the town of Troitsk for construction workers, Russian and foreign specialists, and their families
- Attract new staff and provide basic scientific engineering and technical personnel.
In April 2010, a memorandum of understanding was signed between Russian and Italian teams and a meeting at the Kurchatov Institute followed in May. The meeting set out a preliminary structure: the Italian team will send the entire project documentation to Russia.
The Russian team will develop the documentation and adapt it to Russian norms for construction, installation, safety, and environment. The Italian team also intends to begin building production equipment and materials. In late December 2010, the Italian government allocated the project EUR 35 million per year for three years, and EUR 300,000 for two years for collaboration, Bruno Coppi told Nuclear Engineering International. The Russian government is committed to match those funds, he added. Also, Italian electricity utility Enel has promised substantial aid.
“I will ask for engineers,” Coppi said, although he added that he had not had time to develop his proposals.
The project is led by a 13-member coordinating council. The Italian consortium includes Ansaldo Nucleare, Columbus Superconductors and research centres and universities. The Russian team includes the Kurchatov Institute, SRC RF TRINITI, NIIEFA (Yefremov Scientific Research Institute for Electrophysical Apparatus) in St Petersburg and the State Specialized Design Institute (GSPI) in Moscow. The coordinating council held its first meeting in July 2010.
Author Info:
VE Cherkovets is director of SRC RF TRINITI, Russia, 142190, Moscow Region, Troitsk,
ul. Pushkovykh, vladenie 12.
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| Table 1: Ignitor tokamak in numbers |
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Major radius of the torus R = 1.32 m |
