Plasma Focus Discharge of Low Energy Under Different ......Leopoldo Soto,Cristian Pavez, Fermin...

Thermonuclear Plasma Department

Chilean Nuclear Energy Commission 23rd IAEA TM Research Using Small Fusion Devices

29-31 March 2017, Santiago, Chile

Cristian Pavez1,2, Adolfo Sepúlveda3, Maximiliano Zorondo2, José Pedreros2,

Gonzalo Avaria1,2, José Moreno1,2, Biswajit Bora1,2, Sergio Davis1,2, Maria

José Inestrosa-Izurieta1,2, and Leopoldo Soto1,2

[email protected]

1Comisión Chilena de Energía Nuclear, Casilla 188-D, Santiago, Chile

2Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Chile 3 Facultad de Ciencias, Universidad Mayor, Santiago, Chile

Plasma Focus Discharge of Low Energy Under

Different Regimes of Input Power Density




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




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, 072702 (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.




The Multipurpose generator

PF-400J PF-50J

Multipurpose Generator





C (µF) Lp (nH) Vmax (kV) Eload (J) Imax (kA) T/4 (ns) Z (Ω)

Short circuit

(without electrodes) 1.2 33 30 540 180 313 0.17

“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) 014029 (3pp)





C (µF) Lp (nH) Vmax (kV) Eload (J) Imax (kA) T/4 (ns) Z (Ω)

Short circuit

(without electrodes) 1.2 33 30 540 180 313 0.17

Short circuit

(with electrodes) 1.2 47.5 30 540 150 375 0.2




The X-pinch on Multipurpose generator

12.5

mm




Experimental Setup

Schematic optical setup for a simultaneous Shadow and schlieren

diagnostics

m=-0.75

m=-0.5

m=-f2/f1

Photomultiplier




Main results

Vo = 23.8 kV, p = 12 mbar




Vo = 23 kV, E0=315 J pH = 13 mbar




V0 = 22-23 kV, E0=290-315 J,

pH = 12 mbar




-380 ns -380 ns -330 ns -330 ns -308 ns -308 ns

-272 ns -272 ns -222 ns -222 ns -174 ns -174 ns

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

Schlieren / Shadow Schlieren / Shadow Schlieren / Shadow




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 H2 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.




¡Thank you for your attention!

Plasma Focus Discharge of Low Energy Under Different ......Leopoldo Soto,Cristian Pavez, Fermin...

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