Plasma Focus Discharge of Low Energy Under Different Regimes of Input Power Density

Transcription

1 Plasma Focus Discharge of Low Energy Under Different Regimes of Input Power Density Cristian Pavez 1,2, Adolfo Sepúlveda 3, Maximiliano Zorondo 2, José Pedreros 2, Gonzalo Avaria 1,2, José Moreno 1,2, Biswajit Bora 1,2, Sergio Davis 1,2, Maria José Inestrosa-Izurieta 1,2, and Leopoldo Soto 1,2 1 Comisión Chilena de Energía Nuclear, Casilla 188-D, Santiago, Chile 2 Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Chile 3 Facultad de Ciencias, Universidad Mayor, Santiago, Chile

2 Outline: The context of the presentation Characteristics of design of Multipurpose generator The first experiments in Multipurpose generator (other Z-pinch configurations) The Multipurpose generator in a PF mode. The experimental Setup Main results Summary of the main results

3 The context of the presentation The observations reported here have its starting point at the original attempt to characterize, under different operation parameter, the filamentary structures observed in the current sheath of a small Plasma focus. Filamentary structures in dense plasma focus: Current filaments or vortex filaments? Leopoldo Soto,Cristian Pavez, Fermin Castillo, Felipe Veloso, Jose Moreno, and S. K. H. Auluck. Phys. Plasmas 21, (2014). In order to reproduce the observations on the PF-400J, in addition to expanding the parameter range to other ranges of input power density, the Multipurpose generator in PF mode was adapted. The results reported here correspond to preliminary observations of the Multipurpose generator in a PF mode under different operation parameters.

4 The Multipurpose generator Multipurpose Generator PF-400J PF-50J

5 The Multipurpose generator Design and characterization of a small multipurpose capacitor bank for plasma physics and pulsed power experiments. A Tarifeño, C. Pavez and L. Soto. Phys. Scr. T131 (2008) (3pp) C (µf) L p (nh) V max (kv) E load (J) I max (ka) T/4 (ns) Z (Ω) Short circuit (without electrodes)

6 The Multipurpose generator C (µf) L p (nh) V max (kv) E load (J) I max (ka) T/4 (ns) Z (Ω) Short circuit (without electrodes) Short circuit (with electrodes)

7 The X-pinch on Multipurpose generator 12.5 mm

8 Experimental Setup Photomultiplier m=-f 2 /f 1 m=-0.75 m=-0.5 Schematic optical setup for a simultaneous Shadow and schlieren diagnostics

9 Vo = 23.8 kv, p = 12 mbar Main results

10 Vo = 23 kv, E 0 =315 J p H = 13 mbar

11 V 0 = kv, E 0 = J, p H = 12 mbar

12 Schlieren / Shadow Schlieren / Shadow Schlieren / Shadow -380 ns -380 ns -308 ns -308 ns -330 ns -330 ns -272 ns -272 ns -222 ns -222 ns -174 ns -174 ns

13 Schlieren / Shadow Schlieren / Shadow Schlieren / Shadow -158 ns -158 ns -64 ns -64 ns -40 ns -40 ns -6 ns -6 ns 16 ns 16 ns 24 ns 24 ns

14

15 Summary of the main results The filamentary structure observed from the Shadow diagnostics could be giving account of isolated plasma regions formed by the residual material in the breakdown phase. The discontinuity observed in the plasma filaments suggest to discard the hypothesis of current filaments. For a discharges in H 2 with an anode radius of 3 mm, all shots show a dip and high X-ray yield. The characteristics shown by this plasma focus configuration (without return rods), stimulate to consider new characteristics in the designs of PF's oriented to applications. The design consideration in the PF devices can be extended beyond the currently used scaling rules.

16 Thank you for your attention!