along the axis to the second section. the 8" long insert. Corona is produced at the fire within The second and third sections have an inside diameter of 3.875" central axial electrode 1.25" in diameter, The corona wire enter d contain a the hemi- spring, he wire) spherical end of this electrode and is maintained taut by means o The high voltage supply connects to this electrode (and an internal through a suitable insulator. This dimensional configuration was selected so that no corona is produced except in the wire section. The fourth section contains an axial type of blower designed for but never previously tested at stratospheric altitudes. dviation use, Both ands of the assembly are fitted with butterfly valves operat motor mounted on the external surface of the tube. The active po precipitator are lined with 3 mil aluminum foil upon which the s The high voltage power supply uses a “vitran" (vibrator—transform at a primary voltage of 4.5 volts, The no-load rectified and fil voltage of this device is approximately operating conditions about 170 faa at 2u 2750 volts and it delive 1450 volts, This unit toget hour electrical impulse timer are contained im apressurized c (3 atmospheres air). by a small ions of the le is collected. ) operating red D.C, under normal The circuit used is extremely simple (Figur 12). cam on the timer operates two sets of two switches in accordancs A dual ith the time settings. The first cam is set to close switches B and Bl after e time for ascent has elapsed, (Normally 2 hours). These switches actuate th valve motor, opening the valves, turning on the high voltage and starting the ower, After the set sampling time (6 hours) at altitude has elapsed, the no switches A and Al are actuated, turning off the timer and power s causing the valves to close (through a back contact on the switch blower is also turned off by switch Al, A back contact on the bla may be used for cutting down the balloon load. Power for the blower is obtained from a group of silver cells pro iding 12 volts for 12 ampere hours. Under these conditions (altitude and voltag ) the blower moves 100 cfm at altitude and consumes 1.25 amperes. this unit samples the required 1000 cubic meters. In 6 hours 100 cfm A 4.5 volt 3 AH set of batteries power the timer, H.V. supply and valve motor. The batteries and pressurized container are housed in an insulateq aluminun container. The prsecipitator assembly is spring mounted in a sepagate aluminum angle frame. The entire assembly including batteries and cables Weighs approximately 35 pounds. Calculations indicate that within the range of dust particle sizeq of interest, -05 to 10m, the unit is 100% efficient. Due to the lack of time efficiency tests have not yet been made on this unit. Preparations are now deing made to perform these tests under simulated conditions, The theory of eldctrostatic precipitation and calculations based on this unit are contained iq AppendixD .