ChrispenEvan said:

is this twaddle?

Don Baumea

In 1995, My research on subsonic ramjet engine design was sufficient to build a 55” long research engine.

According to the research, combustion processes create heat, which imparts energy to the compressed air, creating a dramatic expansion of the volume of air. That was the textbook explanation, and still is. Therefore, to the degree that greater heat is created in the combustion process, the greater the thrust produced.

For decades I embraced this explanation of jet engine combustion physics.

Until I read in, “ Introduction to Airborne Radar”, that electromagnetic frequencies relate to various matter ( elements) in a range between fully opaque, to fully transparent. This is a fundamental fact.

OK so far.
Don Baumea said:

As I understood combustion theory until recently, heat, which is primarily electromagnetic energy in the Infrared frequencies, excites kinetically the composition of atmospheric Air.

A bit woolly; heat is defined as a form of energy transfer across the boundary of a thermodynamic system. It can take many forms, and is not primarily IR radiation.
Don Baumea said:

Now that it is clear that nitrogen, which constitutes about 78% of air, is transparent to Infrared energy, meaning no energy is transferred to nitrogen, it stands to wonder if There may be other EM frequencies, created in combustion processes that do impart energy to Nitrogen, but are not exactly known.

He starts off OK, but finishes weakly; nitrogen has been extensively studied, and while it’s true that it’s transparent to IR radiation (and he gets the reason right, below) its absorption spectrum is well known. But that’s me being picky.
Don Baumea said:

I have reason to believe that there may be a far more efficient way to expand nitrogen gas, without creating heat to achieve this. In other words, there may be a set of frequencies that create tremendous gas pressure without any heat, a cold gas system.

In my research ramjet, I evolved to burning metal powders as a way to create much more heat than liquid fuels. Then about 2012 I began exploring heat generated by electric arcs, which can be in excess of 30,000 degrees ( F).

Hmmm… No material can stand temperatures above 5000K without dissociating (evaporating), although he’s not claiming that anything physical has contained anything that hot – the arc can exist in the gas with no contact with anything else (like a lightning bolt)
Don Baumea said:

Now in my new series of investigation with my research ramjet, I will be looking into using Em frequencies exclusively, in a range that imparts significant energy to Nitrogen, but without the detrimental infrared frequencies.

Nitrogen gas does not absorb infrared (IR) light because it is a symmetric, homonuclear diatomic molecule with no dipole moment. For a molecule to absorb IR, its bonds must flex, creating a change in dipole moment, which symmetric nitrogen cannot do. Therefore, infrared radiation passes through nitrogen without causing it to heat up, making it transparent to IR.

This is true.
Don Baumea said:

There is significant data on the interteraction of nitrogen to EUV, Extreme Ultra Violet frequencies.

Quibble: extreme ultraviolet (80-100nm) is usually abbreviated XUV. Aside: nitrogen also absorbs in vacuum ultraviolet (90-190nm), VUV range.
Don Baumea said:

A unique EUV lazer would be the best candidate to inject high energy EUV into the what was formerly the combustion chamber, but now would function as only an nitrogen expansion chamber, a dramatically different component.

The significance of this single modification , to the ramjet cycle, is not readily apparent, it would create the dynamic internal flow to operate without any fuel, fuel injector, and flame holder , and in theory, allows operation from subsonic thru and into the hypersonic range.

Despite his earlier comments (that he can produce high pressure nitrogen without heating it (he uses the term “cold gas”)), he’s proposing the use of a high-powered laser to heat nitrogen to high temperatures.

A fundamental problem, as I see it, is that laser light has a very small divergence (generally in the order of 0.01-0.2°, although laser diodes can be much higher, 10-20°), so using lasers to heat gas requires long, thin tunnels. Lasers are also rather inefficient: a typical UV laser would have trouble converting 10% of electrical power to light, so for this project to work it would need very large power supplies.

Having said that, his physics is mostly solid, and it might work, though it probably wouldn’t be practical.