Pinch modes in the SPEED2 plasma focus

• Autorzy: Kies W. , Decker G. , Berntien U. , Sidelnikov U. , Glushkov D. , Koshelev K. , Simanovskij D. , Bobashev S.
• Języki publikacji: EN

Abstrakty

EN

Deuterium discharges in the SPEED2 plasma focus (80 kJ, 200 kV, 2 MA, 400 ns) have been found unexpectedly stable within the operational regime as a neutron source. Only at higher filling pressures (above 6 mbar) sometimes m=0 instabilities appeared in the pinch column, especially in discharges of lower efficiency (moderate dynamics and neutron yield). Enhancing the electromagnetic radiation by doping these discharges with heavy gases (e.g. neon, argon) distinctly two pinch modes are produced, the micropinch mode (MPM) or the stable column mode (SCM), with a transition regime where the initial SCM is followed by the MPM. Micropinches are local radiative collapses initiated by m=0 instabilities of low-energy- density pinch plasmas. These instabilities and the successive micropinches can be suppressed by kinetic deuterons produced during dynamical compression of high-energy-density deuterium plasma sheaths. Depending on the relaxation of this fast deuteron component the pinch column can be stabilized for several tens of nanoseconds. While the short-lived (appr. 1 ns) micropinches erratically appear as point-like successive flashes along the pinch axis with temperatures about 1 keV and about solid density the reproducible SCM, optimized with respect to the compression ratio, forms a powerful linear radiation source of temperatures and densities similar to the MPM. The SCM needs powerful (fast) drivers in order to use the kinetic ion stabilization, but not necessarily MA currents as available from the SPEED2 driver. This opens the possibility to establish the SCM also in compact experiments like SPEED3 (8 kJ, 80 kV, 0.8 MA, 300 ns) or even SPEED4 (2 kJ, 40 kV, 250 kA, 300 ns).

Słowa kluczowe

EN

pinch plasma; pinch stability; plasma focus; plasma radiation; radiation source

• Wydawca: Institute of Nuclear Chemistry and Technology
• Czasopismo: Nukleonika
• Rocznik: 2001
• Tom: Vol. 46, nr 1
• Strony: 9--14
• Opis fizyczny: Bibliogr. 16 poz., rys.

Twórcy

autor

Kies W.

• Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, Germany, Tel.: [phone], Fax: [phone]

autor

Decker G.

• Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, Germany, Tel.: [phone], Fax: [phone]

autor

Berntien U.

• Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, Germany, Tel.: [phone], Fax: [phone]

autor

Sidelnikov U.

• Institute of Spectroscopy, Russian Academy of Sciences, 142092, Troitsk, Moscow region, Russia

autor

Glushkov D.

• Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, Germany, Tel.: [phone], Fax: [phone]

autor

Koshelev K.

• Institute of Spectroscopy, Russian Academy of Sciences, 142092, Troitsk, Moscow region, Russia

autor

Simanovskij D.

• Ioffe Physico-Technical Institute, Russian Academy of Sciences, St.-Petersburg, Russia

autor

Bobashev S.

• Ioffe Physico-Technical Institute, Russian Academy of Sciences, St.-Petersburg, Russia

Bibliografia

• 1. Decker G, Deutsch R, Kies W, Rybach J (1985) Plasma layers of fast focus discharges – schlieren pictures experimentally taken and computer simulated. Plasma Phys Contr Fusion 27;5:609–619
• 2. Decker G, Flemming L, Kaeppeler HJ et al. (1980) Current and neutron yield scaling of fast high-voltage plasma focus. Plasma Phys 22:245–260
• 3. Decker G, Kies W, Mälzig M, van Calker C, Ziethen G (1986) High performance 300 kV driver SPEED2 for MA pinch discharges. Nucl Instrum Meth Phys Res A 249:477–483
• 4. Decker G, Kies W, Nadolny R et al. (1996) Micropinch actuation in the SPEED2 plasma focus. Plasma Sources Sci Technol 5:112–118
• 5. Decker G, Kies W, Pross G (1983) The first and the final fifty nanoseconds of a fast focus discharge. Phys Fluids 26;2:571–578
• 6. Deutsch R, Kies W (1988) Ion acceleration and runaway in dynamical pinches. Plasma Phys Contr Fusion 30:263–276
• 7. Deutsch R, Kies W, Decker G (1986) Theoretical model and computer simulations of electric signals for magnetically driven plasma sheaths. Plasma Phys Contr Fusion A 28;12:1823–1839
• 8. Jäger H, Herold H (1987) Fast ions kinetics and fusion reaction mechanism in the plasma focus. Nucl Fusion 27;3:407–423
• 9. Kies W (1986) Power limits for dynamical pinch discharges? Plasma Phys Contr Fusion 28:1645–1657
• 10. Kies W (1988) Z-pinch plasmas for nuclear fusion? Habilitationsschrift, Universität Düsseldorf
• 11. Kies W, Decker G, Berntien U et al. (2000) Pinch modes produced in the SPEED2 plasma focus. Plasma Sources Sci Technol 9:279–287
• 12. Mather JW (1971) Dense plasma focus. Methods of experimental physics, vol. 9. Academic Press, New York
• 13. Shearer JW (1976) Contraction of Z pinches actuated by radiation losses. Phys Fluids 19;9:1426–1428
• 14. Steinmetz K (1980) Neutron production and ion beam generation in plasma focus devices. Plasmabericht 1/80. Institut fuer Angew. Physik II, Universität Heidelberg
• 15. Van Calker C, Decker G, Jäger H, Kies W, Rybach J (1985) Pinch formation and reaction proton spectra of SPEED1 focus discharges. Phys Lett A 113;4:203–206
• 16. Voronov AS (1997) A practical fit formula for ionization rate coefficients of atoms and ions by electron impact: Z=1–28. Atomic Data Nucl Data Tables 65;1:1–35