### Abstract

The compression of the plasma focus pinch is a dynamic process, governed by the electrodynamics of pinch elongation and opposed by the negative rate of change of current dI/dt associated with the current dip. The compressibility of the plasma is influenced by the thermodynamics primarily the specific heat ratio; with greater compressibility as the specific heat ratio γ reduces with increasing degree of freedom f of the plasma ensemble due to ionization energy for the higher Z (atomic number) gases. The most drastic compression occurs when the emitted radiation of a high-Z plasma dominates the dynamics leading in extreme cases to radiative collapse which is terminated only when the compressed density is sufficiently high for the inevitable self-absorption of radiation to occur. We discuss the central pinch equation which contains the basic electrodynamic terms with built-in thermodynamic factors and a dQ/dt term; with Q made up of a Joule heat component and absorption-corrected radiative terms. Deuterium is considered as a thermodynamic reference (fully ionized perfect gas with f = 3) as well as a zero-radiation reference (bremsstrahlung only; with radiation power negligible compared with electrodynamic power). Higher Z gases are then considered and regimes of thermodynamic enhancement of compression are systematically identified as are regimes of radiation-enhancement. The code which incorporates all these effects is used to compute pinch radius ratios in various gases as a measure of compression. Systematic numerical experiments reveal increasing severity in radiation-enhancement of compressions as atomic number increases. The work progresses towards a scaling law for radiative collapse and a generalized specific heat ratio incorporating radiation.

Original language | English |
---|---|

Title of host publication | International Conference on Plasma Science and Applications, ICPSA 2016 |

Publisher | American Institute of Physics Inc. |

Volume | 1824 |

ISBN (Electronic) | 9780735414921 |

DOIs | |

State | Published - 30 Mar 2017 |

Event | 9th International Conference on Plasma Science and Applications, ICPSA 2016 - Langkawi, Malaysia |

### Other

Other | 9th International Conference on Plasma Science and Applications, ICPSA 2016 |
---|---|

Country | Malaysia |

City | Langkawi |

Period | 28/11/16 → 30/11/16 |

### Fingerprint

### ASJC Scopus subject areas

- Physics and Astronomy(all)

### Cite this

*International Conference on Plasma Science and Applications, ICPSA 2016*(Vol. 1824). [4978814] American Institute of Physics Inc.. DOI: 10.1063/1.4978814

**Compression mechanisms in the plasma focus pinch.** / Lee, S.; Saw, S. H.; Ali, Jalil.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*International Conference on Plasma Science and Applications, ICPSA 2016.*vol. 1824, 4978814, American Institute of Physics Inc., 9th International Conference on Plasma Science and Applications, ICPSA 2016, Langkawi, Malaysia, 28-30 November. DOI: 10.1063/1.4978814

}

TY - CHAP

T1 - Compression mechanisms in the plasma focus pinch

AU - Lee,S.

AU - Saw,S. H.

AU - Ali,Jalil

PY - 2017/3/30

Y1 - 2017/3/30

N2 - The compression of the plasma focus pinch is a dynamic process, governed by the electrodynamics of pinch elongation and opposed by the negative rate of change of current dI/dt associated with the current dip. The compressibility of the plasma is influenced by the thermodynamics primarily the specific heat ratio; with greater compressibility as the specific heat ratio γ reduces with increasing degree of freedom f of the plasma ensemble due to ionization energy for the higher Z (atomic number) gases. The most drastic compression occurs when the emitted radiation of a high-Z plasma dominates the dynamics leading in extreme cases to radiative collapse which is terminated only when the compressed density is sufficiently high for the inevitable self-absorption of radiation to occur. We discuss the central pinch equation which contains the basic electrodynamic terms with built-in thermodynamic factors and a dQ/dt term; with Q made up of a Joule heat component and absorption-corrected radiative terms. Deuterium is considered as a thermodynamic reference (fully ionized perfect gas with f = 3) as well as a zero-radiation reference (bremsstrahlung only; with radiation power negligible compared with electrodynamic power). Higher Z gases are then considered and regimes of thermodynamic enhancement of compression are systematically identified as are regimes of radiation-enhancement. The code which incorporates all these effects is used to compute pinch radius ratios in various gases as a measure of compression. Systematic numerical experiments reveal increasing severity in radiation-enhancement of compressions as atomic number increases. The work progresses towards a scaling law for radiative collapse and a generalized specific heat ratio incorporating radiation.

AB - The compression of the plasma focus pinch is a dynamic process, governed by the electrodynamics of pinch elongation and opposed by the negative rate of change of current dI/dt associated with the current dip. The compressibility of the plasma is influenced by the thermodynamics primarily the specific heat ratio; with greater compressibility as the specific heat ratio γ reduces with increasing degree of freedom f of the plasma ensemble due to ionization energy for the higher Z (atomic number) gases. The most drastic compression occurs when the emitted radiation of a high-Z plasma dominates the dynamics leading in extreme cases to radiative collapse which is terminated only when the compressed density is sufficiently high for the inevitable self-absorption of radiation to occur. We discuss the central pinch equation which contains the basic electrodynamic terms with built-in thermodynamic factors and a dQ/dt term; with Q made up of a Joule heat component and absorption-corrected radiative terms. Deuterium is considered as a thermodynamic reference (fully ionized perfect gas with f = 3) as well as a zero-radiation reference (bremsstrahlung only; with radiation power negligible compared with electrodynamic power). Higher Z gases are then considered and regimes of thermodynamic enhancement of compression are systematically identified as are regimes of radiation-enhancement. The code which incorporates all these effects is used to compute pinch radius ratios in various gases as a measure of compression. Systematic numerical experiments reveal increasing severity in radiation-enhancement of compressions as atomic number increases. The work progresses towards a scaling law for radiative collapse and a generalized specific heat ratio incorporating radiation.

UR - http://www.scopus.com/inward/record.url?scp=85018520364&partnerID=8YFLogxK

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U2 - 10.1063/1.4978814

DO - 10.1063/1.4978814

M3 - Conference contribution

VL - 1824

BT - International Conference on Plasma Science and Applications, ICPSA 2016

PB - American Institute of Physics Inc.

ER -