Yes, but note that the images only depict half of the pancake coil. To represent the full pancake coil there should be a mirror image below it. In the NMR experiment the two images would be well separated, in your pancake coil the images would be almost touching.
There is something wrong in that analogy. If the pancake coils were driven by separate isolated current sources and there was a potential difference between those sources then your analogy would apply. But that is not the case, the coils are connected and driven from a single source. To establish the Ciw electric field you must examine where the potential difference arises (Verpies showed this in a post but I can’t find it now). Clearly there is a potential difference between each coil’s start (let’s call this the hot end) and finish (let’s call this the cold end) connections, and also from each coil’s hot end to the other coil’s cold end. Where these occur in space depend upon the winding directions, if each coil is CW or CCW then the series bucking connection puts the hot ends together (say on the outer radius) and the two cold ends together (on the inner radius). That minimises Ciw.
Yes, but note the answer to your first question, the image shows only (say the top) half of the pancake coil. Thus a small solenoid that is moved from top to bottom of the pancake coil could exhibit one reversal of polarity as it traverses the top half then another as it moves across the center and another as it traverses the bottom half. But for your pancake coil the middle one might be seen as just a dip in magnitude and you would get just one reversal from top to bottom
Smudge
Smudge, I respectively have to disagree with your above analysis based on the experimental results below. I had worked up my proposal in schematic form but it doesn't exactly fit the test results when the flat coils are driven from the inner leads but I will post it anyway for reference. It does seem to fit however when the coils are driven from the outside leads so more analysis is needed here. Perhaps the phasing of the H1 Field is affecting the inner drive results. Anyway, the first pix is of the test setup which consists of two identical wound solenoid coils placed on top of one another and centered as close as possible in the upper pcb foil traces. The buck inductance measured 57.3uH and the Ciw measured 35pf at low signal levels with this assembly. The first scope pix is with the inside leads of the bucking coils driven by the SG. As can be seen, the open circuit voltages are in-phase but the inner solenoid coil CH2(blu) is considerably lower in amplitude than the outer solenoid coil CH3(pnk). The second scope pix is with the outside leads of the bucking coils driven by the SG. Here the voltages oc are near equal in amplitude and phase which is what I expected to see for the inner drive as well. Both drive conditions above were tuned for resonance and in off-resonance tuning, the phase and amplitude of the solenoid oc voltages would change. Regards, Pm Edit: I have replaced both inner and outer drive scope pix as the previous outer drive data did not have grounds connected on the solenoid coils. Now we see the situation is reversed as the inner solenoid CH2(blu) is higher in amplitude that the outer CH3(pnk). The length of the pcb traces get shorter from the outside to the inside so basically the inner solenoid should not have as much influence from the directional H2 Field as the outer solenoid IMO.
« Last Edit: 2020-07-28, 22:05:44 by partzman »
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Topic: Smudge proposed NMR experiment replication. (Read 289810 times)
