Energy-Loss Mechanisms of a Low-Discharge-Voltage Hall Thruster

e = elementary charge, C fi = ionization mass fraction of the propellant Id = discharge current, A Ii = exhausted ion current, A Isp = specific impulse, s j = ion current density, A=m M = spacecraft mass, kg m = mass of a xenon atom/ion, kg _ m = flow rate of propellant as determined by the mass-flow controller, kg=s P = kinetic power delivered to the spacecraft, W Ps = supply output power IdVd, W Q = average charge state of the ionized propellant q = charge number T = thrust, N Ue = ion velocity, m=s 2 Vaccel = acceleration potential for a given ion, V Vd = discharge voltage (anode potential), V = average offaxis ion trajectory angle t = trip time, s V = velocity increment, m=s ion = ion kinetic energy B = beam divergence as an efficiency c = current efficiency E = energy efficiency p = propellant efficiency probe = the product of all probe-measured efficiencies T = thrust efficiency v = voltage utilization efficiency vdf = velocity distribution efficiency = angle from thruster axis ctg = cathode to ground potential, V plasma = plasma to ground potential, V