Numerical studies of ablated-plasma dynamics and precursor current of wire-array Z-pinches
- Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)
The dynamics of ablated plasmas of wire-array Z-pinches are studied numerically in (r,{theta}) geometry by using the magnetohydrodynamic (MHD) simulation model in which the mass injection boundary conditions are presented, and two-dimensional spatio-temporal distributions of magnetic field and precursor current during the ablation phase are obtained. The ablated-plasma dynamics contains four processes: drifting toward the axis, arriving at the axis and forming the precursor column, and contraction and expansion of the precursor column. The relationship among the maximum inward velocity of ablated plasma streams and the initial wire array parameters is analyzed and it is found that this velocity is relatively sensitive to the change of inter-wire separation but weakly depends on the original array radius. The results are in reasonable agreement with the experiments on MAGPIE facility. The origin of the current flow in the precursor plasmas is analyzed from the point of view of the B-field convection in (r,{theta}) plane. The dynamics of ablation streams determine the distribution of magnetic field and the current density J{sub z} inside the wire array. The precursor current can be approximately calculated by the integral of J{sub z} inside the region of a radius near to the column. In this model, the fraction of precursor current is less than 10% of the total current, which is close to the experimental results. When the current waveform is fixed, the increase of the inter-wire gap or decrease of the initial radius will lead to the increase of the precursor current.
- OSTI ID:
- 21537652
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 18; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
The role of magnetic field in the transition to streaming ablation in wire arrays
Ablation dynamics in wire array Z-pinches under modifications on global magnetic field topology