Natural Science Forum / Physics / Optics / July 2008

I know all of the inventors listed on that patent. They're very good.

The reason a roots blower is used is because it is a positive
displacement device, so it works well under a lot of back pressure. And
a lot of back pressure is what you get because in order to produce a
stable high-voltage discharge, your nozzles have to have a lot of
expansion.

Leaving aside the engineering difficulties involved in getting a vacuum
cleaner to work in a laser gas, impellers are not positive displacement
and lose flow drastically when there is a lot of back pressure. PRC has
made impellers work in DC-excited fast-flow lasers but it wasn't easy.

I would be 300X amazed if you got any kind of discharge going with a
vacuum cleaner.

Thanks for the reply.
I guess a lot of expansion is good for keeping the gas cool.  But why
does gas expansion make the discharge more stable?  I know we are
looking for a smoothly ionized gas mixture, but what makes that
possible in a turbulent high-speed flow?
A roots blower is the best choice, but would a regenerative blower
work in this application?  It's more expensive than a vacuum cleaner
motor, but cheaper than a roots blower.  I know it's not positive
displacement, but it seems PRC made their own design based on the
regenerative blower.  Now I'm referencing U.S. Patent # 4,817,111.

Justin H. | NE Ohio
         | CO2 lasers, Tesla coils, RF
         | Electronics, Linux, AsteriskPBX
         | Espresso

Thanks for the reply.
I guess a lot of expansion is good for keeping the gas cool.  But why
does gas expansion make the discharge more stable?  I know we are
looking for a smoothly ionized gas mixture, but what makes that
possible in a turbulent high-speed flow?
A roots blower is the best choice, but would a regenerative blower
work in this application?  It's more expensive than a vacuum cleaner
motor, but cheaper than a roots blower.  I know it's not positive
displacement, but it seems PRC made their own design based on the
regenerative blower.  Now I'm referencing U.S. Patent # 4,817,111.

ugh, my newsreader didn't auto quote your previous message.
It should be easier to follow, now.

Justin H. | NE Ohio
         | CO2 lasers, Tesla coils, RF
         | Electronics, Linux, AsteriskPBX
         | Espresso

Back in the old days of usenet, we used to reply to our own messages to
remind people we were still watching them.
I wonder if they still do that?