TJ-II project

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Top view of the TJ-II stellarator

The TJ-II project is the flagship project of the National Fusion Laboratory of Spain. TJ-II is a flexible, medium-size stellarator of the heliac type, the second largest operational stellarator in Europe (after W7-X).

TJ-II has a major radius of 1.5 m, an averaged minor radius 0.2 m and a magnetic field of 1 T. The highest temperatures are achieved by microwave heating (800 kW at 53 GHz) and by accelerated neutral hydrogen beam (1.6 MW and 30 keV). TJ-II has 92 access windows for experimental diagnostics and machine systems.


TJ-II was designed in collaboration with Oak Ridge National Ridge (USA). Its construction has been partly financed by EURATOM (preferential support). The first plasmas were produced in late 1997. The main TJ-II construction milestones were:

  • 1990: European financing support approval:1990

    Foto grupo Fusión 1996

    TJ-II group in 1996

  • 1991: End of design and start of fabrication:1991
  • 1996: Construction completed: October 1996
  • 1996: Magnetic surface mapping
  • 1997: End of Commissioning
  • March 1998: First physics results
  • 2008: Achievement of Low to High (L-H) transition using neutral beam injection and lithium wall conditionin

TJ-II experimental phases:

Stage I:

TJ-II model - Top view

TJ-II model – Top view

  • Heating by the resonance to the Electron Cyclotron frequency (Electron Cyclotron Resonance Heating)
  • Injected power 600 kW
  • Low density, high electron temperature plasmas

Stage II:

  • Neutral Beam Injection Heating
  • Injected power 2 MW
  • Studies on dense, high beta plasmas


The goal of the TJ-II project is to study the physics of magnetically confined plasmas, with emphasis on the influence of the magnetic configuration on heat and particle transport. These studies should contribute significantly to international efforts towards developing magnetic confined fusion as an energy source.

TJ-II model - Cutaway view

TJ-II Model.


The TJ-II group is organized into Divisions and Units:

  • Operations Division
  • Experimental Physics Division
  • Engineering Unit
  • Theoretical Physics Unit

TJ-II in the FusionWiki

Interactive data display

Copia de plasma verde