[extropy-chat] LASER: DARPA's HELLADS small laser weapon makes headway

[Mike Lorrey]

--- Dirk Bruere <dirk.bruere at gmail.com> wrote:
> > 
> > Okay,
> > 1) MIRACL was vastly larger system than the current MTHEL system.
> > 2) you've got two quotes there saying "a few inches" NOT "twelve
> > inches". "A few" is taken as two or three in colloquial US english,
> > which is far closer to my estimate than to yours.
> 
> 
> Or as I said, 12cm ie around 4 inches.
> Still, the figures would apply even if it were only 3 inches.
> And since we're being picky the power density I was working with was
> 1320W per sq cm.

Sorry, I thought you had said 12 inches, not 12 cm. However, you still
need to scale your 12 cm by one to two orders of magnitude downward for
a fighter portable unit, which should be 12 mm or less.

> 
> > Now that we've disposed with that objection, lets do some realistic
> > calculations of the effects of 150 kW hitting a missile casing in
> > an area of less than 20 mm radius.
> > 
> > No, let's do a realistic calculation of a power density of 1kW per
> > sq cm.

Once again, you are cooking the books and spreading the butter thin.
Firstly, you are ignoring the fact that the HELLADS system is said to
be utilizing dynamic focusing technology, and applying THEL scaling to
a device two orders of magnitude smaller. A 12 mm beam would be a power
density of 1326 kW/ sq mm, not centimeter.

Another issue is pulse length. Watts measures beam power in
Joules/second. However beam pulses are generally fractions of seconds.
If, for example, the laser is 150 kW with a pulse time of 0.1 sec, the
energy is delivered at a rate of 1500 kJ/s. The determinant of
ballistic effect of a laser is more properly expressed by its
Joules/sec rating.

Mike Lorrey
Vice-Chair, 2nd District, Libertarian Party of NH
Founder, Constitution Park Foundation:
http://constitutionpark.blogspot.com
Personal/political blog: http://intlib.blogspot.com

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