TJ-II:Magnetic configuration

The magnetic configuration of TJ-II in vacuum is completely determined by the currents flowing through the external coils. Magnetic configurations are labelled as 'xxx_yy_zz', where

• 'xxx': 10 times the current (in kA) in the circular coil
• 'yy': 10 times the current (in kA) in the helical coil
• 'zz': 10 times the current (in kA) in the vertical field coils

The current in the toroidal field coils is not specified, as its value is adjusted to guarantee central absorption of the Electron Cyclotron Resonant Heating source (requiring a specific value of the magnetic field on the magnetic axis).

Often used configurations are:

Configuration	$\iota (0)/2\pi$	Volume (m3)	Magnetic well (%)	Minor radius a (m)
100_28_59	1.375	0.8111	1.9	0.1760
100_32_60	1.423	0.934	2.0	0.1880
100_36_62	1.467	0.987	2.2	0.1950
100_40_63	1.509	1.065	2.2	0.2030
100_44_64	1.551	1.287	2.4	0.2220
100_48_65	1.591	1.2043	2.46	0.2160
100_50_65	1.614	1.260	2.5	0.2210
100_68_72	1.770	1.226	2.36	0.2210
69_41_51	1.515	0.580	2.5	0.1509

Flexibility

Flexibility diagram of TJ-II magnetic configurations. Several lines of constant rotational transform are highlighted and labelled with the corresponding central $\iota /2\pi$-value.

TJ-II has considerable configurational flexibility, as observed in the 'flexibility diagram'.