X‐ray diagnostics of plasma focus DPF‐78 discharge with heavy‐gas admixtures

The x‐ray structure (λ<10 A) of the DPF‐78 discharge was investigated with different heavy‐gas admixtures to a basic D2 filling. A possible classification of plasma features is proposed. Micropinches with an unusual high aspect ratio of about 10:1 were found. Soft x‐ray spectra of single micropinches were registered on film. The use of x‐ray spectroscopic methods by means of spectra simulation codes allowed us to estimate the parameters of particular types of pinches with axial size of 0.5 mm and full radial size of 0.05 mm. In the He‐like ionization state we obtained ne≊3×1021 cm−3 and Te≊0.8 keV. The electron temperature determined in the H‐like ionization stage was considerably higher, Te≊2 keV, indicating a strong ionizing plasma. Possible deviations from the Bennett condition are discussed in connection with the spectroscopic results.

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