The second idea that could equalize the magnitude of the positive and negative ion currents in the
ionizer output was to use separately adjustable AC and DC voltages on the field emitting needles. The attempt 
was made with boil off nitrogen gas in the same arrangement that had difficulty achieving equality
of the ion currents in late August 2014 at LHO with AC excitation alone. The experiment showed that
the DC of either polarity and amplitude in combination with AC made no improvement in the equality 
of the ion currents over a range of pressures on the needles between 300 to 900 torr. It was bad 
advice from the "experts" in the electrostatic reduction business. This leaves dry air, tried earlier
this week, as the best method to achieve robust equal magnitude positive and negative ionization. Let's
hope that the optical coating tests being carried out at Caltech show no increase in absorption from the
ionized air.

A report of the ion currents comparing dry air and boil off nitrogen as the carrier gas will be posted later.