*http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance <http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance>*
Magnetic fields will always produce RF. Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation. This energy is at a specific resonance frequency which depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms. A tester could determine exactly what were the isotopic contents of the reactor from the NMR frequencies coming out of the reactor. This is why Rossi may be silent about the RF emissions from his reactor. On Sat, Oct 4, 2014 at 10:07 AM, Jones Beene <[email protected]> wrote: > > > Although the stainless steel version of the Rossi HT is effectively > shielded and cannot release RF, it should be mentioned that this stainless > tube itself could have been added specifically as a way to keep RF from > being transmitted ! (that should be your argument Axil) > > > > I have private email from a Rossi observer who agrees that Andrea Rossi > did talk specifically about the SiC tubes, and that he appears to have > removed all of the reference from JoNP. > > > > This does not mean SiC is relevant, just because it was removed, but there > is also another argument for why RF could be there. We have talked about > the Mossbauer effect wrt the Rossi effect before. Ni-61 and K-40, both of > which are assumed to be involved in the Rossi effect are Mossbauer > isotopes. Let’s say for the sake of argument that the first HT from > Brasimone was indeed housed in SiC. If the reaction involves an high energy > effect in nickel (Mossbauer effect, or a variation), then RF could have > been an early problem which was solved by switching the external tube to > stainless. An internal tube could still be SiC which is proved to provide > IR superradiance at 11 microns (27 THz). This IR could stimulate RF. > > > > https://www.mail-archive.com/[email protected]/msg82733.html > > > > Not sure if this is related to why Axil thinks RF will appear, but if so, > then the spectrum is predictable and one could see an induced RF effect in > the long twisted pair conductor of the power cables. If it is there, then > it will probably show up in the range of 2 MHz > > > > > > > > *From:* Jones Beene > > > > In addition to what Bob says, the problem with RF as a signature for the > Rossi effect, is that it would have been spotted before now. > > > > Because the wiring in Labs (or homes) is of an effective length which > makes it a good antenna, even when carrying 60 Hz, any significant RF will > have a noticeable effect, especially a visible effect on lighting. Also > effected would be radios, cell phones, hearing aids, Wi-Fi etc … almost > everything except the microwave oven, the transmitter of which has been > designed into what is an excellent Faraday cage. > > > > *From:* Bob Higgins > > > > Normally the resistivity of a metal is linear in degrees Kelvin. So, > going from 300K to 1300K would cause a metal's resistance to increase by > 1300/300 or a factor of 4.3. The RF skin depth will increase as the square > root of this change or about 2. So, the leakage out of this Faraday cage > will about double in amplitude (6 dB). In an ideal Faraday cage (ideal > conductor), all of the RF is reflected back into the interior, none leaks > out, and none is absorbed. In a real metal Faraday cage, most of the > signal is reflected, the signal is attenuated substantially in going from > inside to outside, and some of the power is absorbed in the metal. The > amount that leaks out is proportional to the number of skin depths in > thickness of the Faraday cage metal. The skin depth is 1/sqrt(pi F mu > sigma), so it is inversely proportional to the square root of frequency. > High frequencies have small skin depth and hence, the metal thickness being > more skin depths in thickness, the signal transmitted is more attenuated > going through the metal. Thus, low frequencies with big skin depths > penetrate better and high RF frequencies penetrate less. That is why I > said that it is unlikely that high RF frequencies would escape in a > measurable way - given the thickness of the reactor metal (probably on the > order of 1.5mm) above 100 kHz would probably be considered high frequency. > And, as previously stated, about 6dB more will come out at 1000C than at > room temp. > > > > Bob Higgins > > > > Axil Axil wrote: > > Dear Bob > > > > Unlike myself, it is great that you are an expert in this subject that > greatly interests me. > > > > Please address this issue. Unlike the usual RF shielding applications > using stainless steel, the Hot-Cat reaches 1000C without active heat > removal. > > > > Bearing in mind that RF shielding protection is a function of the > conductivity of the metal, the electrical resistance of stainless steel is > a increasing function of temperature. How much RF protection is lost in a > 1000C stainless steel faraday cage as a function of the increasing > temperature of stainless steel. > > > > > http://www.aksteel.com/pdf/markets_products/stainless/austenitic/304_304L_Data_Sheet.pdf > > Electrical Resistivity of 304 stainless in > > (microhm-cm) > > 68°F (20°C) – 28.4 (72) > > 1200°F (659°C) – 45.8 (116) > > > > > > On Fri, Oct 3, 2014 at 11:27 AM, Bob Higgins <[email protected]> > wrote: > > Yes Axil, I am an RF engineer and I am aware of permalloy/supermalloy > sheets used in EMI protection. These materials are added in sensitive > instrument applications to shunt low frequency evanescent magnetic fields, > not propagating RF EM fields. As I said, RF fields above about 1 kHz would > be prevented from escaping from Rossi's hotCat by the hermetic stainless > steel reactor enclosure acting as a Faraday cage. There will be no > propagating RF escaping from the Rossi's reactor vessel. There is only the > possibility of low frequency evanescent fields escaping. > > > > Bob Higgins > > > > > > On Fri, Oct 3, 2014 at 9:11 AM, Axil Axil <[email protected]> wrote: > > > http://webcache.googleusercontent.com/search?q=cache:http://aip.org/tip/INPHFA/vol-7/iss-5/p24.pdf > > > > *How does magnetic shielding work?* > > All EMI shielding materials are manufac- > > tured from high-permeability alloys that con- > > tain about 80% nickel; the alloys vary in the > > composition of their remaining metals. They > > are usually fabricated as foils or sheets and > > are baked at 2,000 °F in a dry hydrogen-rich > > atmosphere to anneal them. Annealing sig- > > nificantly improves a material’s attenuation, > > that is, its ability to absorb and redirect mag- > > netic fields. > > > > A shielding alloy works by diverting a > > magnetic flux into itself. The alloy redirects > > the magnetic flux away from the sensitive > > object and returns it to the north–south > > field. Although the field from a magnet is > > greatly reduced by a shield plate, the protec- > > tive alloy itself is attracted to the magnet, > > but with no ill effects. Closed shapes are the > > most efficient for magnetic shielding—cylin- > > ders with caps, boxes with covers, and simi- > > lar enclosed shapes are the most effective > > (see figure). > > > > Magnetic shielding materials offer a very- > > high-permeability path for magnetic field > > lines to travel through, directing them > > through the thickness of the shielding alloy > > and keeping them from going where they > > are not wanted. It is important that the > > shield should offer a complete path for the > > field lines, so that they do not exit the mate- > > rial in a place where they will cause unin- > > tended interference. > > > > *What is the difference between RF shield -* > > *ing and magnetic shielding?* > > > > Ra d i o-frequency (RF) shielding is > > required when it is necessary to block high- > > frequency (100 kHz and above) interference > > fields. RF shields typically use copper, alu- > > minum, galvanized steel, or conductive rub- > > b e r, plastic, or paints. These materials work > > at high frequencies by means of their high > > c o n d u c t i v i t y. Unlike magnetic shields that > > use their high permeability to attract mag- > > netic fields, RF shielding has little or no > > magnetic permeability. However, when they > > are properly engineered and constructed, > > magnetic-shield alloys become broadband > > shields that protect against both EMI and > > RF interference. > > > > >
