Checking the Practicality

You would need something to step up the voltage to at least 100V and convert it to AC in order to excite the plasma inside. But certainly the inverter technology exists.

But 40W / 6V = 6.67A. If you were thinking this was going to come from a D Cell battery system and illuminate for even 1 hour, that's a LOT of 1.5V cells. Lets say you bit the bullet and buy a 6V lantern battery. It has an amp-hour rating of 1100mAh, so 1.1Ah. If you had seven of them in parallel, then fed them into something that would boost the voltage, you could theoretically get 1 hour out of them (because the inverter would have losses). But in reality to avoid over heating the batteries you would be restricted to about a 300mA drain rate. So to get 6700mA, you will need 24 batteries. If you wanted 10 hours from it, start looking for lead-acid batteries from old pickup trucks or early sixties Volkswagen Beetles, and build a sturdy rack to hold them.

Ok i understood the complexity but what exactly does "LUMBERJACK" mean???

Wictionary - useful to find out what words mean in many languages...

http://en.wiktionary.org/wiki/lumberjack

Actually, so a search on "The Lumberjack Song" from Monty Python.

Does "flourescent" mean "built from finely milled grain"?

No "fluorescent" lamp mean the hallow tube and of two electrodes, I am an Indian and I don't know if fluorescent lamps will be made of milled grain

a very straight answer to a very straight question - YES.

for all who believe that it can be done . . . a SOLAR POWERED manned airplane has made a successful flight in Europe recently.

OK there are costs - huge costs . . . there are technical viability issues . . . simply put the question is - is the exercise worth it?

so one day if engineers keep dreaming and working . . . we will either make it viable to have a 40W bulb lit from a 6Vdc source - or - we will have sufficient data and reason to defer the thought to a later date when we are more knowledgeable . . .

keep trying . . . the future belongs to dreamers . . .

thank you sir, triggered the thoughts to the future of the idea