Fig. 1. Schematic of experimental setup. A detailed description of all settings can be found in the text. It is important to note that photodiode-1 measures the luminosity in both the vessel and the right-side extension tube, while photodiode-2 measures only the luminosity in the left-side extension tube, aiming to monitor when the plasma begins to eject axially.

Fig. 2. Temporal profiles of drive current (light salmon pink), magnetic field (purple), and luminosity (rose), measured at 20 Pa and 20 kV, with a time resolution of 0.01 μs.

Fig. 3. Observation of bulk plasma motion. (a) Time-series images of magnetized plasma implosion within the second half-cycle of the pinch. The exposure time for each frame is 15 ns. (b) Time variation of the radius of the outer boundary of the plasma column, as extracted from (a). The curve is included to guide the eyes.

Fig. 4. Time-dependent plasma density and temperature. Stage-1 and Stage-2 refer to the last microsecond of the first compression and the initial microsecond of the second compression, respectively, during which the plasma undergoes adiabatic compression and heating. The uncertainty in electron-density measurement is ∼10%, introduced by the theoretical uncertainty and the error of the FWHM measurements.⁴⁵ Electron temperature was measured using line-to-continuum thermometry,⁴⁷ the theoretical uncertainty of which is negligible, and the accuracy in temperature measurement is better than 10%.

Fig. 5. (a) Detailed evolution of the trapped magnetic field and its derivative, as well as the driving magnetic field, during magnetized plasma compression. (b) Illustrations of magnetic transport in the first compression phase. In each illustration, the outermost ring represents the drive coil, with the driving current flowing counterclockwise. Adjacent to the coil is the vessel wall. Further inside, the ring composed of red and blue curved arrows represents the current sheet, with directional arrows indicating different induced electric fields: the electric field E_θd induced by changes in the driving magnetic field B_d, and the motional electric field E_v×B induced by the bulk plasma motion across the field lines. The blue–gray ringed region displays plasma that has undergone compression, while the uncompressed ambient plasma is situated in front of it. The dot and cross symbols in the diagram represent magnetic fields pointing outward and inward from the page, respectively.

Fig. 6. Plots of T_f/T_i vs n_f/n_i for adiabatic compression. The adiabatic compression curve is plotted in accordance with the adiabatic relation. The blue star and green square represent the experimental results, corresponding to Stage-1 and Stage-2, respectively.

Fig. 7. Self-luminosity profile of the plasma within the time range under study (taken from Fig. 2), and the associated rates of radiative recombination and three-body recombination.