In the figure, a 100mA current flows through a copper wire 0.10mm in diameter, a 1.0mm diameter glass tube containing a salt solution, and a vacuum tube where the current is carried by an electron beam 1.0 mm in diameter. The density of conduction electrons in copper is 1.1×10^29 m^-3 . The current in the solution is carried equally by positive and negative ions with charges +/- 2e the density of each ion species is 6.2×10^23 m^-3 . The electron density in the beam is 2.5×10^16 m^{-3}. Find the drift speed in the electron beam.