Observation of multiply charged states ions in a high-power pulsed reflex discharge

Abstract

Time-resolved optical emission spectroscopy studies have been made to investigate the elemental/charge composition of the plasma ionic component at pulsed reflex discharge. The discharge plasma has are registered spectral lines neutral atoms and ions of the working gas Ar, Ar 1+ , Ar 2+ , and also of the cathode material: Zr, Zr 1+ , Zr 2+ , Zr 3+ . The presence of zirconium in the spectrum attests to the entry of cathode material into the plasma and its subsequent ionization. The variation of spectral line intensity with time in the early stage of the discharge and in the stage of dense plasma existence (time interval from the onset of the discharge up to 4 ms) correlates with the dynamics of plasma parameters. Characteristic times of appearance of excited atoms and ions in the plasma have been determined. The time of appearance of excited Zr * atoms is by the order of magnitude longer than that of Ar * . The stage of high-voltage mode exhibits the lines of excited Ar * , Zr * atoms and Ar +* , Zr +* ions, with the intensity of which sharply increasing during the transition to the high-current mode. The excited Ar 2+* , Zr 2+* , Zr 3+* ions appear later, when the discharge has already gone into the high-current mode.

First experiments on ICRF discharge generation by a W7-X-like antenna in the Uragan-2M stellarator

“…With increasing anode voltage, their start times migrate to step 2 (figure 9 b ). The difference of t app for excited ions and atoms by an order of magnitude may be explained by a cascade mechanism of ion excitation (Kovtun, Shapoval & Siusko 2019). The corresponding thresholds for the lines O II 441.5 nm and He II 468.6 nm are 26.3 and 51.0 eV, accordingly (Kramida et al.…”

Using microwave refraction to determine local inhomogeneities of a rotating plasma

“…An experimental study of dense multicomponent plasma was carried out on the MAKET facility. The experimental setup is a Penning cell in which high--power pulsed refl ex discharge in cross electrical and magnetic fi elds is realized [17]. A schematic representation of the MAKET facility is shown in Fig.…”

“…The time dependence of the integral fl ow of plasma emission from the discharge was registered using the photod etector. The photodetector is manufactured on the basis of the photodiode FDUK-13U and operates in a photodiode mode [17]. The photodiode has a wavelength range of  = 180…1100 nm with a maximum sensitivity at 940 nm [18].…”

Comparative analysis of the plasma parameters of ECR and combined ECR + RF discharges in the TOMAS plasma facility

“…The single ionization cross-section is greater than the multiple ionization cross-section. The formation of multiply charged ions occurs more efficiently in successive processes of single ionization of an atom (ion) [56]. Let us estimate the characteristic times of He 2+ formation (ionization collision time) τ i = (N He + <σv>) −1 , where <σv> electron impact ionization rate, in the reaction He + + e → He 2+ + 2e, for ECR discharge and ECR + RF discharge taking into account the experimental data N He + ≈ N e .…”