From: vitalmis@optusnet.com.au   
      
   iain-3@truecircuits.com wrote:   
      
   >   
   > 1. The problem with a molecule that might break up is... that a   
   > population   
   >    with two very different charge/mass ratios will deliver worse   
   > overall   
   >    Isp and thrust to power than a population with the same average   
   > charge/   
   >    mass but a single ion species?  An example:   
   >      Thruster1: one ion species, 40 km/s exhaust velocity   
   >      Thruster2: two ion species, 30 and 50 km/s exhaust velocity,   
   >                 half of each kind of species.   
   >    If both thrusters flow 1g/s of propellant, both produce 40 newtons   
   > of   
   >    thrust.  At perfect efficiency, Thruster1 uses 800 kW, and Thruster2   
   >    uses 850 kW.  Clearly thruster1 is better.   
      
   I was under the impression that energy is used in breaking up molecules and   
   contributes nothing to the thrust.   
      
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