Axial and Temporal Gradients in Mo Z Pinches
Three nested molybdenum wire arrays with initial outer diameters of 45, 50, and 55 mm were imploded by the {approx} 20 MA, 90 ns rise-time current pulse of Sandia's Z accelerator. The implosions generated Mo plasmas with approximately 10% of the array's initial mass reaching Ne-like and nearby ionization stages. These ions emitted 2 - 4 keV L-shell x-rays with radiative powers approaching 10 TW. Mo L-shell spectra with axial and temporal resolution were captured and have been analyzed using a non-LTE collisional-radiative model. We find significant axial variation in the plasma conditions, with electron densities increasing from the cathode ({approx} 3 x 10{sup 20}cm{sup -3}) to near the anode end of the plasma ({approx} 3 x 10{sup 21}cm{sup -3}) and electron temperatures decreasing slightly from the cathode ({approx} 1.7 keV) to the anode end ({approx} 1.5 keV). Time-resolved spectra indicate that the peak electron density is reached before the peak of the L-shell emission and decreases with time, while the electron temperature remains within 10% of 1.7 keV over the 20 - 30 ns L-shell radiation pulse. Finally, while the total yield, peak total power, and peak L-shell power all tended to decrease with increasing initial wire array diameters, the L-shell yield and the average plasma conditions varied little with the initial wire array diameter. Radiative cooling is likely to play an important role in the wire array plasma development.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15014662
- Report Number(s):
- UCRL-JRNL-205451
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 3 Vol. 12; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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