Near-earth Thin Current Sheets and Birkeland Currents during Substorm Growth Phase
- Princeton Plasma Physics Laboratory
Two important phenomena observed during the magnetospheric substorm growth phase are modeled: the formation of a near-Earth (|X| {approx} 9 R{sub E}) thin cross-tail current sheet, as well as the equatorward shift of the ionospheric Birkeland currents. Our study is performed by solving the 3-D force-balance equation with realistic boundary conditions and pressure distributions. The results show a cross-tail current sheet with large current (J{sub {phi}} {approx} 10 nA/m{sup 2}) and very high plasma {beta} ({beta} {approx} 40) between 7 and 10 R{sub E}. The obtained region-1 and region-2 Birkeland currents, formed on closed field lines due to pressure gradients, move equatorward and become more intense (J{sub {parallel}max} {approx} 3 {micro}A/m{sup 2}) compared to quiet times. Both results are in agreement with substorm growth phase observations. Our results also predict that the cross-tail current sheet maps into the ionosphere in the transition region between the region-1 and region-2 currents.
- Research Organization:
- Princeton Plasma Physics Lab., NJ (US)
- Sponsoring Organization:
- USDOE Office of Science (SC) (US)
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 813623
- Report Number(s):
- PPPL-3809
- Country of Publication:
- United States
- Language:
- English
Similar Records
Current sheet thickness in the near-earth plasma sheet during substorm growth phase
Birkeland currents in the plasma sheet