Global currents and e ± production in the aligned rotator. The white region above the polar cap is the zone of outflowing current, the shaded gray region indicates the bulk return current, and the thick black curve shows the separatrix return-current layer. The hatched area indicates the closed zone. The null charge line (dashed) is defined by ρ GJ = −Ω · B /(2π c) = 0; above the line ρ GJ < 0 and below ρ GJ > 0. Episodic e ± discharge occurs in the outflowing current above the polar cap (α > 1), in the bulk return current above the polar cap (α < 0), and in the bulk return current outside the null line (α > 1). Beam instabilities occur outside the light cylinder where e ± is created by the intersecting gamma-ray beams with different directions.