TJ-II:Interferometry

TJ-II has two interferometry systems for the measurement of the line-integrated density.

The Microwave interferometer

The diagnostic is located in sector B8. The probing beam has an inclination of 18.7º with respect to the vertical and a frequency of 140 GHz, corresponding to a wavelength of λ = 2.14 mm. The diagnostic provides a time trace of the-line integrated electron density (65536 points, sampling rate 100 kHz). The signal is less reliable for high densities (above 2-3 10¹⁹ m^-3). This time trace is fundamental for machine operation.

The CO₂ interferometer

The probing wavelength is about 10 μm.