MIZUNO REPLICATION AND MATERIALS ONLY

  • An the 2 replications in Japan? Is that successful replications by 2 independent groups or the same group with 2 separate, successful replications?


    I mixed up Japan/China with Zhang, as Can points out. So 1 success each in China, France, Japan. Anyone with better intel, please feel free to add/subtract.

  • There has been also a rather liberal replication attempt in Utah that did not seem to show results, but I'm not sure if it should be counted as the setup and methods were significantly different than Mizuno's due to equipment limitations. It did use a Ni mesh with Pd burnished on it though.

  • All 3 calibrations show nonlinear behaviour don't they? ... to more or less the same extent?


    Things (literally) straighten out above 80 Watts heater power and again below 40 Watts.


    My cell is designed with two thermocouples, mounted at 0 and 90 degrees angle on the circumference to give some indication of the radial heat distribution. My comment referred to the linearity between these two thermocouples over the operating temperature range. Here's a chart that shows the unusual behavior with Argon. The data calculation has been added to the archive at https://tinyurl.com/sdmrc3l


  • I'm curious knowing what would be the surface temperature of the heater (assuming it's internal as in Mizuno's case) at an average reactor vessel surface temperature of 400 °C; do you have any estimation about it?


    The heater cartridge glows bright orange at 160 watts, as viewed through the open end of the thermo-well. But I think what you're asking is the temperature of the outer wall of the thermo-well tube, the surface exposed to the mesh. I haven't come up with a way to measure it, but it's certainly over 400°C. When the cell was last apart, that surface showed only slight discoloration, not surprising since it was never fully heated in the presence of air.

  • magicsound

    Yes, I'm referring to the surface exposed to the mesh, although it sounds like it must be visibly incandescent.


    One thing I'm wondering if there could be any possible thermionic effect at play at low pressure, especially if a suitable voltage difference exists between the heater (thermowell tube) and the mesh (inner wall of the reactor tube). This would also change depending on the heater's (thermowell tube's) surface coating.

  • The heater cartridge glows bright orange at 160 watts, as viewed through the open end of the thermo-well.


    Because of the loss of convective/conductive cooling effects. the heater gets way hotter for the same input power when the reactor is under vacuum - then there is only radiative cooling, plus some small contribution from the thermowell's point of contact with the flange on the reactor. It really does make a huge and visible difference.

  • can The cell is made entirely of 304 alloy stainless steel, including the thermo-well. The work function of the major constituents (Ni, Cr & Fe) ranges 4.5-5.15 eV. It should be possible to calculate the emission current at a given temperature, and I encourage readers to attempt that. The maximum temperature reached in calibrations was 397°C.


    Direct measurement of thermionic current is not possible due to the cell construction, but an insulated Safire type tungsten probe might work to probe for internal e-field,

  • The cell is made entirely of 304 alloy stainless steel, including the thermo-well. The work function of the major constituents (Ni, Cr & Fe) ranges 4.5-5.15 eV. It should be possible to calculate the emission current at a given temperature, and I encourage readers to attempt that. The maximum temperature reached in calibrations was 397°C.


    I found this graph which suggests it would be negligible for clean metallic surfaces at the temperatures of interest. Things may change significantly with oxide- or graphite- coated surfaces:


    Saturation thermionic current density at different temperatures and for different work functions eϕ, as determined from the total thermionic current


    https://encyclopedia2.thefreed…y.com/thermionic+emission



    Related read: http://www.r-type.org/articles/art-217.htm


  • This morning I pumped out the cell again, then loaded 1010 Pa of D2 using 10 mg of LiAlD4 in a small stainless steel ampoule. The live test is now under way, with data streaming on Youtube:

    https://www.youtube.com/watch?v=qGSw_ir2JuM

    Chat is on, so post your questions and comments there.


    Post-event update:

    This run covered up to 70 watts heater power and 229 °C. The temperatures matched the master calibration within one degree, so definitely no excess heat.

    Power was turned off at +6 hours and the cool-down was recorded. The data for this test will be added to the archive, and a new run starting at 50 watts will begin tomorrow at around 17:00 UTC.


    AlanG

  • The next part of the MR1 replication attempt is now live at:

    https://www.youtube.com/watch?v=Cc1VlBpzpgY


    Starting at 70 watts heater power, this test will cover the remaining temperature steps up to 400°C. Cell pressure at start-up was 940 Pa, showing substantial absorption of D2 from the 1008 Pa initially loaded. Some calibration points to watch are 70w=229C, 80w=250C, 90w=275C, 100w=292C, 110w=310C, 120w=330C, 130w=347C

  • Some calibration points to watch are 70w=229C, 80w=250C, 90w=275C, 100w=292C, 110w=310C, 120w=330C, 130w=347C


    Alan you should softly cycle around the nickel currie point at 354C this is one key task to induced the reaction 347 is no high enough!

    We usually do one first step much higher than the involved currie points and afterwards a full cool down follows.

  • Thanks for the suggestion Jurg. I am planning to cycle around 130w/347C for that reason. It will be late in the day when that is reached, not very convenient for those watching in EU. That said, the system is stable enough that many further tests should be possible over the next days.