Date:  Thursday, 08/09/07   Time:  3:45-5:00 pm 

Place: TA-03, Bldg. 215, Physics Auditorium 

Refreshments & Collaboration:  3:15 pm

Speaker:  Yevgeny Raitses
          Princeton University
          Princeton, NJ



Hall Thrusters for Space Applications: Advanced Concepts and Research Challenges


The Hall thruster is a plasma propulsion device that holds considerable promise for many space missions. 
Unmagnetized ions (usually Xenon) are accelerated electrostatically to energies of 0.1-1 keV in a 
quasineutral plasma (1011 -10 12 cm-3 ) with a closed electron E x B drift. This thruster concept was 
invented in early 60’s to overcome the limitations of a gridded ion thruster, in that the Hall thruster
produces neutral plasma flow that is not space-charge limited, but is instead limited by the attainable
magnetic fields in the thruster magnetic circuit. Over the years, more than 100 Hall thrusters have been
flown in space. Future space applications, including micropropulsion and high power nuclear electric 
propulsion, can take Hall thruster technology to its technological limit. With recent advances in 
understanding of Hall thruster physics, we suggested further improvements of these devices by controlling
plasma-wall interaction and electron cross-field transport. I will discuss fundamentals and potential 
applications of several advanced thruster concepts, including our cylindrical Hall thrusters with a 
mirror-type magnetic field configuration. In recent experiments with non-self-sustained operation, these
thrusters featured significant plasma plume narrowing (20-30%), accompanied by significantly enhanced
(50-60%) efficiencies. The fact that the plume narrowing is so striking motivates new propulsion and
non-propulsion applications, which will also be discussed.