Bomb-pumped lasers use a nuclear explosion to generate a coherent source of   
   X-rays and redirect it in the form of a laser toward its targets (shortly   
   before the explosion itself destroys the device).   
   You need a coherent source of X-rays for a X-ray laser, and the only other   
   known generator would be an expensive, difficult(if possible at all)-to-build,   
   unwieldy, weaker kilometre(s?)-long free electron laser.   
      
   Casaba Howitzers use a nuclear explosion to power a plasma lance. It is   
   simpler to build, but less efficient and shorter-ranged. It is still a   
   formidable weapon, so if you can't build or don't want to pay for bomb-pumped   
   lasers, it may be useful.   
   However, you can't really use the plasma as an X-ray generator, so you   
   wouldn't use it as the basis of a bomb-pumped laser.   
      
   The reason for having the rods of the bomb-pumped laser aiming at multiple   
   targets is that originally, it was supposed to be a ballistic missile   
   interceptor. As such, each device was aiming at many targets, as the full   
   force of one would be overkill for    
   a single target. The idea is, after all, to not need one nuke to stop each   
   enemy nuke.   
   However, I don't see anything preventing the rods to all point in the same   
   direction, to form a single more powerful, longer-ranged beam. It wouldn't be   
   as efficient as a wildly divergent aim, as on average, rods would be less   
   parallel to the emitted X-   
   rays (a rod won't redirect nearly as many X-rays if they arrive from a side   
   than from behind), but it would still most probably be more powerful than a   
   Casaba Howitzer, and certainly longer-ranged.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)