[Technical Thread] Brightness of the reactor glow in the Lugano pictures and reactor temperature

Hello all,

I'm new to the forum but I noticed that it is hard to have a focused technical discussion when the topic involves Rossi's reactors.
As I'm interested in discussing the brightness issue I asked the moderators for some help.
They have kindly suggested the concept of "technical threads":

Quote from LENR-Forum

Consider this as "Technical thread".
It starts with some assumptions and try to dig in some technical problems with bounded scope. Debate should be in the topic, and disagreement can be deep but should be kind and in-topic.

Moderators will remove/move any off topic post, like those discussing of general question, conspiracies, off-topic theories, side questions... Any aggressive, repetitive, annoying comment too, not simply insults.

For off-topic exchanges, a parallel [Debate Thread] will be created, with usual rules.
See here: [Debate Thread] Brightness of the reactor glow in the Lugano pictures and reactor temperature

Thus, for this first technical post, the subject is the use of the pictures of the glowing reactor included in the Lugano report to derive constraints on the reactor temperature.

As we are all aware, the thermal camera measurements have been widely criticized for using the wrong emissivity. Bob Higgins suggests that the real temperatures were closer to 1130 C while Thomas Clarke gives re-calculated temperatures ranging from 713 to 779 C.

The reactor appears in figure 2 where it doesn't seem to be glowing, although the heater wires within the insulating hollow alumina tubes are faintly glowing. In figures 12a and 12b it is clearly glowing.

Unfortunately the lighting conditions of figures 2, 12a and 12b are all different.

The illumination in figure 2 includes at least two point sources, as can be deduced from the shadows of the metal framing on the wall and of the tripod leg on the framing.

Figure 12a, which is taken from almost the same point of view of figure 2, lacks any obvious point sources.

Figure 12b appears to have been taken in the dark.

Of course this is an ill-posed problem and a number of assumptions have to be made, and this is why discussion on a forum is likely to be helpful.

I propose the following approach:

- (1) Make assumptions about the spectral responsivity of the three camera channels (R, G, B)
- (2) Estimate the radiance of different objects, based on reasonable assumptions on the illumination conditions and on the radiance of self-lit devices in the three bands
- (3) Average the sensed intensities in the three channels from the images over objects for which the radiance is estimated, and over the reactor areas
- (4) Deduce per-channel radiometric conversion coefficients for each image
- (5) Use radiometric conversion coefficients to convert the sensed intensities over the reactor areas to radiances
- (6) Calculate the predicted integrated reactor radiances for the three R, G and B channels at different reactor temperatures and emissivities
- (7) Deduce the range of plausible temperatures.

I have some results for (1) and have performed some work on (3) and (6), but it's work in progress. I think (2) is the most difficult and most error-prone part. Steps (5) and (7) should be routine.

The goal is to obtain a plot like the following:

(EDIT: V2 of the plot attached. Predictably, there was a silly mistake in the previous plot in the K→T conversion where I added instead of substracting, resulting in a large error.)

The biggest problem with that plot is that the dashed reference line is quite arbitrary (in addition to possible calculation errors.)
I have assumed that a 200 W blackbody 3300 K source illuminates a wall having a reflectivity of 0.7.

Also, any auxiliary information such as the following will be welcome:

- Information on the model of camera used for the Lugano report
- Information on the spectral sensitivity and particularly the near-infrared sensitivity of various commercial cameras
- Information on the room or its lighting
- Information on the backlight radiance of the PCE-830s or the scale used in fig. 1

Hopefully this thread will be a productive one and we'll settle this question; there is a chance that the outcome won't be indeterminate.

Also, information on the spectral emissivity of alumina in the visible as a function of temperature would be welcome. Most plots I have seen stop at 10000 cm^-1.

Attached is a useful picture provided by Eric Walker on the "Experimental evidence on Rossi devices" thread. It was a Facebook link, I have copied it to imgur for convenience (hope this is OK with Eric.)

The description was:

Quote

Live colour calibrator shaping up nicely!

[]=[lexicon]Project Dog Bone[/lexicon]=[]

Alan Goldwater has been doing more work today on the live temperature calibrator which is intended to be able to be used as a live reference for temperature in further []=[lexicon]Project Dog Bone[/lexicon]=[] tests. This will mean that whatever camera/exposure etc pictures are taken with - there will be a known reference temperature for comparison.

Alan adds more detail on the first test

"Here's the color calibrator at target temperature (870 C on coil #2).

It's more efficient than the design estimate, just under 900 watts required.

The target temperatures are (left to right) 590, 760, 870, 1000. I'll add three more thermocouples tomorrow and see how close the others are to spec.

The camera used is an Olympus 560UZ, 1/125 sec. f/5.0, ISO200"

Please note this a "work in progress"

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EDIT: Additionally, I found this document:
http://www.image-engineering.d…uer_spectral_response.pdf

It provides carefully measured spectral response curves for a number of different camera models, but not for the 560 UZ (although I came accross that document while searching for Olympus 560 UZ).

Also, the 560 UZ is an older camera (from about 2007) that has a CCD sensor according to http://www.dpreview.com/reviews/olympussp560uz
The Lugano images seem to have been taken with a compact handheld (based on the reflection of the photographer's hand in the PCE-830 screen) and it may therefore have a CMOS sensor (as is also suggested by the fixed pattern noise in the blue channel of the "dark" reactor picture.)

Quote from axil

@Antoine10FF

In the "Experimental evidence on Rossi devices" thread example above, how is the shadow effect of the heater coils shown in figure 12a and 12b in the Lugano report produced? I do not see coil shadow depicted. Such simulation might be done by using a tungsten rod heater inside the coil to simulates the hot opaque core. Such a configuration properly displays the solid black body heat generating properties of a solid emitting black body that the reactor core would produce. From the Cook report, we know that the core of the Lugano reactor was cemented into a solid aggregation of the fuel. The solid core of the reactor has no transparent emissivity issues associated with alumina. This blackbody radiation behavior does not change between a complete solid filling the core or a tube like coating forming on the inside of the core's surface.

Hi Axil,

Those plots make the simplistic assumption that all we have is a glowing blackbody of unit emissivity. Thus there is nothing about coil shadows.
This would be valid if the whole reactor core was glowing as a grey body at the reported temperatures.

I like your suggestion of having a blackbody inside an alumina tube. I have no facilities to perform such experiments myself, however I can set up a better model. And, for that, the information you provide on the reactor structure is much appreciated.

Do you think you can correct or complete the diagram below of the reactor?

I also found some data about alumina's spectral emissivity in the visible region at different temperatures, and it looks like the visible emissivity increases with temperature. This will also have to be taken into account.

http://web.archive.org/web/200…logies/pdf/1999crd128.pdf

Is anyone able to quickly set up a radiative transfer simulation based on the geometry and the alumina emissivity? If not I may attempt to kludge something myself.

Quote from axil

I looked up the dimensions of a commercially available alumina tube closest to the 2 cm alumina tube used in the Rossi reactor. It was in millimeters 19.05OD x 14.30ID. The Lugano reactor was also covered with alumina heat fines and pure alumina cement which complicates things.

See

http://www.sifferkoll.se/siffe…10/LuganoReportSubmit.pdf

The temperature of the surface of the reactor refected the temperature of the heater wire more than the core of the reactor. The wire cast a shadow from the light produced by the core so the core was hotter than the heater wire.

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OK so let's try to have a model with a hot core and wires. The thing I'm not sure about is this. The heater wires seem to be wound in a spiral configuration, but are they embedded in alumina? I would tend to think yes, but I'm not sure.

Also, once a model is running, it is easy to change the temperature of the course to test different hypotheses, including the 1450 C.

Quote from David Fojt

you drew the fuel core that touch reactor core, instinctively..
Therefore, the fuel is never drawn as touching the wall in Rossi's patent..
May be it is a central powder pellet...?

Good point, the label should be changed by replacing "fuel" with "reaction chamber" to avoid making unsupported assumptions.

Quote from H-G Branzell

Axil, how can you believe this? Look at the few centimeters of the heating wires that are sticking out from the dogbone end caps. They are producing an intense heat glowing like incandescent lamps. They produce the same heat per length unit inside the dogbone but there they are in a more compact spiral configuration. But you believe that they appear as shadows. Just because the stupid Lugano report said so or what?

That's interesting but you are forgetting the thickness of the alumina. Let L_w be the radiance of the glowing wires. This depends on their emissivity and temperature.

Inside the reactor, you have (to appease skeptics, allegedly) a source of heat that glows with a radiance L_r, some thickness x1 of alumina, then glowing wires of thickness x2, then some thickness x3 of alumina.

Ignoring scattering within the alumina, at the surface of the reactor, regions where the reactor glow is not shadowed by the heater wires have radiance

L1 = L_r (1-R)^2 exp(-C (x1 + x2 + x3))

where R is the reflectivity and C [cm^-1] is the effective scattering coefficient of alumina,
and x1 + x2 + x3 is the thickness of alumina, from the glowing reactor core to the surface.

In the shadowed region, we assume that we only see the hot wires thru a thickness x3 of alumina so that the radiance is

L2 = u L_w (1-R)^2 exp(-C x3)

where u is a parameter that varies from 1 to 3 to describe the extent to which the three heaters contribute to the unshadowed radiance; if there was no scattering, because the wires do not overlap, we would have c equal to one. But we can adjust c to partially account for scattering, although c cannot exceed three because there are only three wires. I think u would be closer to 1 than 3.

Let S = L2 / L1 (< 1) be the shadowing ratio.

By looking at the red channel of the image from fig. 12a in the Lugano report, I have measured that the wire shadows cause a dip from 1.00 to 0.75 in the signal; the background level measured from alumina nearby at approximately the same illumination angles is about 0.72, so that the signal goes from 0.25 to 0.03, implying S ~ 0.12.

We have

S = L2 / L1 = u L_w (1-R)^2 exp (-C x3) / L_r (1-R)^2 exp(-C (x1 + x2 + x3))
= u L_w / L_r (exp (-C (x3 + (+x1 +x2 +x3)))))
= u exp(C(x1 + x2)) L_w / L_r

Therefore

ln (S L_r / (u L_w)) = C(x1 + x2)

And thus the first constraint is S L_r / u L_w >= 1.

Hence L_r/L_w >= u / S

For u=1 we need L_r/L_w > 8.4 but if we take u=3 we need L_r/L_w >= 25.

(This is the ratio of integrated, excess radiances in the red channel.)

If we assume that the wire and the core have the same emissivity, a 75 degree difference if the wire is at 450 degrees, to a 150 degree difference if the wire is at 1000 degrees is necessary to give an 8.3:1 ratio, while these numbers go up to 150 degrees at 450 to 300 degrees difference at 1000 degrees for a ratio of 25.

According to the latest plots aboveplot below, a 50 degree difference is sufficient to cause a factor of 4× change in the radiance in any of the visible bands.

For the second constraint, we have x1 + x2 = ln (S L_r / (u L_w))/C
Based on Yamashita 2008, around 600 nm we have C ~ 2.0.

A minimum possible value for x1 + x2 would be x12_min = 2 mm.
Thus

ln (S L_r / (u L_w)) / C > x12_min

which is

u > exp(C x12_min) / (S L_r/L_w)

For u=1 we get 1.5 / (0.12 * 8) = 1.56 so it is true, and for u=3 we have 1.5 / (0.12 * 25) = 0.5 and it is true by default

In fact we can solve for L_r/L_w and what we really need is exp(C x12_min)/S = L_r/L_w ~ 12.5

Therefore wire shadows having a contrast of 8:1 as seen in the Lugano fig 12.a images are possible provided the temperature differential between the heater wires and the core is on the order of 100-200 C.

EDIT: Black body band radiance ratio plot.

Quote from Paradigmnoia

Antoine10FF,
The cross section diagram should have an air gap where the "alumina?" arrow points, surrounding the inconel. Whether it is actually air is open to some debate. At high temperature, it may be rather rarified in there, or H could be in there to some degree, etc.

Hi Paradigmnoia,

Is this a known fact, a good supposition or a guess?

I think that won't change my calculation above. It would be something to take into account for a finite element model.

Quote from oystla

Has this been discussed, or anyone with thoughts on the matter?

One would Expect that LENR have a different energy emission spectrum than electrical heated alumina.

The way I think of this is that whatever the LENR emission spectrum is, it is produced inside the reactor core, which I assume is some pressure and heat-resistant material, say some kind of steel. The reactor core would then thermalize the emissions. In the visible, IIRC steel's spectral emissivity is more or less flat, thus we would have a grey body spectrum.

Quote

Alumina transmittance and LENR energy spectrum is unkown parameters in the Lugano test.

[...]

If there are high energy emission in a part of the spectrum of high alumina transmittance, then this would not be picked up as heat signal, and energy production may actually be underestimated by the Lugano report.

Yes but let's try to keep the topic on the visible emissions.

Even in the visible, alumina's optical properties are temperature-dependent, and it is hard to come by data that covers the visible range and the temperature range we're interested in.