I wonder if high-density charge storage devices like DRAM could be somehow used for detection under certain operating conditions.
Such a scheme has been patented, at least for cosmic rays. See the following reference. I have not investigated the details, so its applicability would need to be investigated further
One of the things that Mizuno replicators are going to have to get to grips with is Vacuum systems. I must confess that my experience has been limited to 'roughing pump' territory and I found this free book (which is around $150 on Amazon) really helpful.
Another good book is Building Scientific Apparatus by Moore, Davis, and Coplan. The book has a chapter devoted to vacuum technology including useful equations, vacuum measurement, and vacuum pumps. I found this book invaluable in designing and constructing a roughing plug turbo pump system capable of 1e-7 Torr. Hint: all high vacuum components utilize metal-to-metal seals.
Jeff
"30 ga tungsten wire will oxidize (and possibly burn) readily in oxygen if heated up to glowing for long periods"
Agreed. That is why, like Parkhamov's experiment, the tungsten wire I plan to utilize will be maintained in a hydrogen atmosphere. Kanthal, by comparison, is much more tolerant of an oxygen atmosphere. In my setup the tungsten wire, alumina tube etc. are maintained under either vacuum or <100 Torr hydrogen.
"The electrical (and thermal) conductivity of SiC increases rapidly with temperature."
The same holds true for tungsten, such as Parkhamov used in one of his later experiments. Kanthal, by comparison, yields a nearly flat resistivity vs. temperature curve. A 300K to 1500K temperature difference for W produces a 7.1 resistance ratio whereas Kanthal produces a ratio of only 1.06. This requires that the heater power supply for tungsten must be capable of furnishing a much higher voltage. For example: A 40V supply worked fine for Kanthal, but tungsten will require a 150V supply. Selection of the tungsten wire diameter becomes more complicated because it's necessary to trade off the length of wound wire against the allowable space on the alumina tube. Furthermore, this calculation must be made assuming a certain maximum temperature. Too fine a wire gauge produces too high a resistance and does not permit the windings to cover the necessary length of the tube. Too large a gauge cannot meet the desired resistance while still fitting onto the tube. In my case it turns out that 30 ga is the optimum. That equates to 2.88 Ohms/ft at 1500 K, 7.29 ft, 111 turns and a 50% density winding length of 2.2". In my experiments the SS tube inside the alumina tube is approx 1.5" in length.
Alternatives to Joule heating.
Has anyone looked into the use of SiC in a microwave oven as a means of achieving high temperatures? SiC is a strong microwave absorber and should therefore work as a heating element; it can tolerate temperatures substantially higher than either Kanthal or alumina. Additionally, SiC is chemically inert to most compounds or elements at elevated temperatures. One problem I foresee is controlling precisely the microwave oven power. Perhaps some type of phase control circuit would work.
Jeff
"I always wondered why rather use an SS tube than alumina as fuel tube ? Is there a secret to using an SS ?"
The reason is most likely the same as that which convinced Parkhomov to include an SS tube in his later experiments. Lithium, or lithium compounds react with alumina far more readily that they will with SS. I first ran a Parkhomov-type experiment with Ni + LiAlH4 in an alumina tube. The result was a near instantaneous erosion of the alumina resulting in the lithium mixture melting (burning) through the alumina.
"The Kanthal, if embedded, will easily reach its melting point before the surface temperature gets to close to that temperature due to the insulation and fairly poor heat conduction qualities of alumina ceramics. In some cases the Kanthal wire could be hundreds of degrees hotter than the alumina."
As part of the calibration process I measured simultaneously the external temperature of the Kanthal wire wound over the alumna tube (via IR thermometer) and the temperature inside the alumina tube (via type K thermocouple). There was a difference of 23-32 degrees C between the two, where the IR thermometer recorded the higher temperature. Given that the uncertainty of knowing the effective emissivity Kanthal and alumina, this temperature delta is acceptable and can be figured into subsequent measurements. In other words, I did not observe hundreds of degrees difference between the Kanthal temperature and that inside the alumina tube.
Another point: the fact that the SS tube melted indicates that temperatures inside the alumina tube (and presumably inside the SS tube) exceeded the MP of stainless steel (~1400 C). An exothermic reaction inside the SS tube, combined with Joule heating, would account for the melting of the SS tube as well as that of the Kanthal wire.
Given that Ti has a very high affinity for hydrogen, I thought it might be interesting to run a Parkhamov-type experiment with Ti rather than Ni. In this case I loaded 100 mg LiAlh4 and 1g 200 mesh Ti powder into a 0.188" OD stainless tube 2" in length. The ends were plugged with fused quartz wool. Then the SS tube was placed in a 0.25" OD alumina tube around which was wrapped 32 T of 0.032" Kanthal wire. The entire apparatus described above fits into a 38 mm OD fused quartz tube that has connections to DC power, vacuum, and H2. The quartz tube is capped on both ends by machined endpieces with radial O-ring seals. I have no trouble maintaining 1e-6 Torr or better vacuum under continuous pumping. The experimental protocol went as follows.
1. Evacuate cell at room temperature to 1e-6 Torr or better.
2. Introduce 20 Torr dry H2
3. Step the heater voltage from 0V to 35V in 5V increments. This yields heater power from 12W to 540W and cell temperatures from ~100C to 1100C.
4. Add/bleed H2 from external source as required to maintain a pressure of < 100 Torr (This is the limit of the Baratron). I wanted to ensure that the system operated at sub 1 atm pressure for safety reasons.
5. Record alumina tube surface temperature and Delta T from the airflow calorimeter vs. heater power. I used an IR thermometer to monitor the temperature of the alumina tube.
The first run showed no excess heat as compared to a Ni + LiAlH4 + H2 mixture. The results were also nearly identical to running with an empty (no Ni or LiAlH4) cell. No excess heat, and the calorimeter delta T closely matched values for an empty cell.
The second run produced something unexpected. At a 35V heater voltage the Kanthal suddenly burned out. This was surprising since a 35V heater voltage has previously yielded
surface temperatures of <1100 C maximum. I was not able to record the cell surface temperature at the time of burnout because of heavy sputtering on the interior of the quartz tube. Also, the calorimeter did not have time to reach a steady state.
Upon disassembling the cell it was obvious that the SS tube and its contents exceeded 1500C: see attached photo. So the question is whether the sudden increase in temperature was due to chemical or LENR causes. I'll repair the apparatus and repeat the protocol and see what happens.
Comments are welcome.
Jeff
Airflow Calorimeter Notes
Attached are notes that detail the mechanical and electrical construction of an airflow calorimeter suitable for making measurements on a Mizuno-type apparatus. The notes include construction details, circuit schematics, and a dry run set of measurements demonstrating the ability of the setup to produce a nearly linear power in vs. inlet to outlet temperature rise. Power resolution is approximately 2 watts, and maximum power capacity is in excess of 300 watts. Temperature resolution can be improved by post processing temperature data. Maximum power capacity can be increased by enlarging the enclosure and/or increasing the airflow rate.
Jeff
Parts for the Sorensen power supply arrived today. The cell shown above is now installed in the airflow calorimeter. First calibration run will be with the cell open to the atmosphere (CF flanges in place but not tightened down) but otherwise configured as if filled with H2 or D2. Input parameters include: ambient temperature, DC voltage and current (and hence power) applied via Joule heating. Output measurements include internal cell temperature, as measured by a coaxially situated thermocouple, and the inlet-outlet temperature differential of the calorimeter enclosure. Previous calibrations with this calorimeter have yielded a nearly linear power in vs. delta T graph. So I expect to see similar results, although the slope of the line may be different.
Jeff
Heater Jacket for Mizuno Cell
I received the ceramic braided nichrome and wound approximately 20 feet of it around the 8"x1.5" CF nipple. The windings are held in place with Sauereisen type 78 ceramic cement. A type K TC is placed inside the thermowell. Room temperature resistance for the nichrome wire is approx 1 Ohm/foot. The resulting 20 Ohms is a good match to the Sorensen DCS 150-7 power supply that can provide 150V @ 7A. I'm still waiting for a fan for the Sorensen supply, so a 200 W HP supply is being used as a stand-in. Even with its limited 200W capability, it is possible to achieve a TC temperature of 200C. This should be sufficient for following Mizuno's protocol. Attached is a photo of the cell.
"This is similar to what I found with my small cell. A heater in the thermowell resulted in lots of out-gassing from the small metal tube due to its exposure to high temperature."
Magicsound,
Sounds like a good idea and one that I had been considering. Could you provide me with a mailing address or a mail address so I can get one of the heaters you mentioned above.
Jeff
Location of Heater for a Mizuno-type Experiment
I have completed constructing a somewhat smaller version of a Mizuno cell: 8" long x 1.5" tube OD. Ends terminate with 2.75" CF flanges: one end with a 1/4" VCR fitting and the other with a 1.33" CF reducer. For the latter end I fabricated a 3/8" thermowell that is Ag brazed to a 1.33" CF end cap. The thermowell accommodates a 1/4" x 6" 400W sheath heater. I have been able to achieve 2e-6 Torr or better vacuum (using roughing and turbopumps), and also have demonstrated that the cell will maintain ~5 Torr H2 pressure indefinitely. A type K TC is mounted on the cell and held in place by a hose clamp.
The next step is heating. This was done with no Ni and ~5 Torr of H2. By applying ~65W to the heater I was able to observe a surface temperature of ~120 C. So far so good. However, at that power setting the heater glows bright red and is near the limit of its operating range. If it's necessary to achieve higher cell surface temperatures (as recommended one of Mizuno's papers) then another method of heating may be required. Three options come to mind.
1. Reduce the thermal resistance between the thermowell and the sheath heater. Typically this is done by precision reaming the thermowell ID a few mils larger than the heater OD. However the thermowell ID is too large for this approach. Cementing the heater into the thermowell is also an option but makes replacing a failed heater element difficult.
2. Apply heat externally to the cell's circumference. One method I have used in the past entails applying an electrically insulating layer to the exterior of the cell and winding NiCr or Kanthal wire around the circumference of the cell. This places the heating element in closer proximity to the rolled Ni mesh.
3. Add insulation around the cell's circumference while retaining the sheath heater in the thermowell. This approach modifies the thermal gradient and reduces the amount of power to the heater to achieve a given temperature at the cell's exterior.
Since I intend to measure excess enthalpy via an airflow calorimeter the method of heating the cell should not matter.
Comments or recommendations?
Question regarding D2 gas Purity.
Does anyone have any insight regarding the required purity of D2 for a Mizuno replication? My reason for asking is that, rather than bother with bottled D2, I'm going with a hydrogen generator. There is a minimum amount of liquid H2O or D2O required to partially fill the reservoir, and that minimum is about 1 liter.
The 1-liter D2O I purchased is specified to be 99% pure. Is this good enough? Would it be feasible to use a 50/50 mix of D2O and H2O?
Getting back into experimentation.
It's been a couple of years of hiatus caused by family medical issues, but these seem to be under control, at least for now. I have fabricated a Mizuno-type apparatus and am about to start. The only missing ingredient is Pd coated Ni. It would seem that electroplating, rather than rubbing, would yield a more uniform Pd depth, and this is what I would like to pursue. Wet chemistry is not my forte, however. Does any one have knowledge of a service that can electroplate Pd over Ni? The preparatory steps typically involve degreasing and electro-cleaning. I have found several such services on the internet, but they will not do work unless it is for a corporation or a university, as opposed to an individual.
Jeff
The repair parts for four bellows valves arrived today, and I wasted no time disassembling and cleaning the valves and installing the new valve seats. Before repairs it was impossible to pull better than 2e-5 vacuum. With the repairs I can get 1e-7 after an hour. The four valves comprise a manifold that permits the test cell to be evacuated, filled with D2, and sealed off from the rest of the vacuum system. A 10 um restrictor orifice is plumbed in line with the D2 generator and is required to introduce gas at a slow enough rate to fill cell pressure to a desired ~10 Torr, pressure. D2 may be supplied either from a cylinder or, more likely, from a hydrogen generator using D2O.
Parts also arrived to fabricate the test cells. In this case, 7" long 2.75" CF nipples. A 2.75" to 1.33" reducer was used on one end in order to more easily achieve a gas tight joint between the thermowell tube and the end flange. I bored and reamed a 0.375" hole in the 1.33" flange and then silver brazed the tube and flange. It would be more difficult to perform this operation with a 2.75" flange, due to its larger thermal mass. There are only a few more parts required to complete the system, and then it's on to procuring Ni, D2, and Pd.
The vacuum system is put back together. There is now a valve between the forepump and the TM pump to prevent backflow. Right now I am testing just the vacuum system to determine how good a vacuum can be attained. The forepump can easily get down to a few milli Torr in a few minutes. The T/M pump gets down to < 1e-6 Torr after an hour. My suspicion is that the new Viton gaskets in the HV side need to be baked out to reach a lower value. The next step will be to add an RGA to identify which gas species are present and need to be removed. Does anybody have suggestions for a good brand of RGA?
Two steps forward, one step back... The first attempt to operate the T/M pump yielded an acceptable vacuum on the range of 1e-8, as measured with an ionization gauge. At this time I decided to shut the system down for the day. Somehow during the shutdown process the forepump must have backstreamed some oil into the T/M pump, despite the presence of a trap. The next time the system was evacuated it was impossible to achieve better than 1e-4 vacuum. So I had to tear down everything and wash it out with acetone (including the T/M pump).
The next step is to install a solenoid-operated isolation valve (Edwards type PV25EK) that is slaved to the forepump power. That should take care of backstreaming. Another thing learned: install viton CF gaskets at first to make sure everything works. Then, and only then, replace them with Cu gaskets. Besides being expensive, the latter are a royal pain to install and remove.
After a seemingly infinite time, the last UHV vacuum components arrived yesterday. So today I assembled the components (using nitrile gloves to minimize contamination) and began pumpdown. The setup is shown below. The two baratron controllers on the left monitor forepump pressure and the UHV chamber pressure. The first controller is configured to turn on the T/M pump when the pressure falls below 3 Torr. The second controller monitors a heated 1 Torr F/S baratron and is configured to permit the Ionization gauge to power on for pressures < 0.1 mTorr. As soon as I get pressures less than 0.1 mTorr I'll turn on the ionization gauge and see how good an UHV is possible.
Jeff
Has anyone out there investigated the applicability of open-source molecular modeling software packages to LENR and, if so, can they recommend one? The analogy I would apply is the difference between breadboarding electronic circuits vs. simulating them in HSPICE. Changes and measurements for the latter can be done many times faster and often give better control-ability and observe-ability.
Simulations can even yield non-obvious results. Consider the case of the FPU problem that demonstrated non-ergodic behavior for an ensemble of coupled nonlinear harmonic oscillators. Nonlinear potentials also can give unusual results (energy localization) for continuous media, as in the case of the KDV equation governing solitons.
