Numerical experiments for radial dynamics and opacity effect in argon plasma focus
A z-pinch in its simplest form is a column of plasma in which current (J) is driven in the axial direction (z) by an electric power source producing an azimuthal (θ) direction magnetic field (B) that tends to confine plasma by (J × B) force. One application of this configuration is Plasma Focus....
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
2012
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| Subjects: | |
| Online Access: | http://eprints.intimal.edu.my/1004/ http://eprints.intimal.edu.my/1004/1/Numerical%20experiments%20for%20radial%20dynamics%20and%20opacity%20effect%20in%20argon%20plasma%20focus.pdf |
| Summary: | A z-pinch in its simplest form is a column of plasma in which current (J) is driven in
the axial direction (z) by an electric power source producing an azimuthal (θ) direction magnetic
field (B) that tends to confine plasma by (J × B) force. One application of this configuration is
Plasma Focus. Dense plasma focus (DPF) is essentially a pulsed electric gas discharge between
coaxially arranged electrodes. DPF devices belong to the family of dynamic Z-pinches which
are self-constricted plasma configurations. The Lee model code was developed to simulate the
plasma dynamics in a DPF. The model incorporates the energy and mass balances equivalent,
at least in the gross sense, with radiation-coupled dynamics to all the processes which are not
even specifically modeled. It is a well known fact that radiation loss is an inevitable phenomenon
in the final stage of pinch compression. The most obvious one is that of a focus or a Z-pinch.
Plasma self-absorption is an important factor during the pinch compression. In this paper the
effect of self absorption of line radiation was investigated in argon plasma by a series of numerical
experiment considering both aspects, i.e., by including and excluding the self absorption term
in Lee code. The results were compared for various parameters, i.e., Radial trajectories, pinch
duration, pinch current, line radiation yield while changing pressure. The effect of radiation self
absorption was observed in last few fractions of seconds (200–300 ns). Considering self absorption,
the compression shows a value of radius of about 0.2 mm while a collapse (radiative collapse) was
observed otherwise. The results illustrated that the radiation cooling becomes significant when
the plasma is dense and turn to be opaque for radiation. Hence in real case we do not see a
radiative collapse in argon PF as self absorption plays in real experiments. The results of pinch
duration and pinch current also indicated that self absorption is essentially enhancing the pinch
in terms of stability. |
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