2. The discharge is excited in the lamp by HF generator
3. The radiation is emitted along magnetic lines of force through a cylindrical orifice made in one of the pole tips. The magnetic field strength between the pole tips of the electromagnet is changed by a voltage ramp driver
4 and measured by Hall sensor 12. The Zeeman components σ+ and σ− are separated in time using a polarizing modulator, which consists of photoelastic modulator
5 operating at a modulation frequency of 50 kHz, driven by quartz oscillator
6, and polarizer
7. After the polarizing modulator, radiation passes through analytical cell
8, interference filter
9 with the peak transmittance at λ = 254 nm, and is detected by photodetector
10. Signals from the photodetector output arrive at electric signal processing unit
11, where the signals modulated at frequency S1 and dc signals S0 are separated and an analytical signal, related to the differential cross section ΔQ by the Eq.