Australian engineers have just announced what they claim is a much
more efficient ion thruster:

http://www.e4engineering.com/item.as...ews&ch=e4_home

It's been pointed out that ion thrusters are more efficient on Isp,
but they produce less thrust -- too little to be of use for launching
to orbit. By a factor of how much are ion thrusters too weak for
achieving escape velocity?
By how many times would the above system have to be improved to be
used for SSTO?

I presume that nuclear power can be used to augment the
thrust/efficiency of electric propulsion. Would it be enough?