Grenade coil type systems

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OverUnity Research > Electrical / Electronic Devices > Tariel Kapanadze's Devices (Moderators: verpies, Apecore) > Grenade coil type systems

2024-11-26, 12:28:17
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Author Topic: Grenade coil type systems (Read 39774 times)

picowatt	Re: Grenade coil type systems « Reply #475 on: 2023-10-29, 21:35:41 »
Sr. Member Posts: 453	Quote from: Itsu on 2023-10-29, 21:04:44 verpies, PW, It takes some time (minutes) to position the probe on the correct positions which is OK with no power through the coil, but with 8A through it, i have only a minute or so before the coil heats up too much. But i was able to make these measurements with the probe in the middle of the gap: probe position current through coil flux measured 0° 0A S 0mT 0° 8A S 6.8mT (cannot get it to 0mT) 90° 0A S 171mT 90° 8A S 104mT Itsu Itsu, If I understand this correctly, the max field strength of the field parallel to the sausage axis with the coil deactivated is 171mT (seems low...). And, the max field strength when measuring the strength of the radial field produced when the DC coil is activated is 104mT. Is that correct? I would have guessed the difference between the parallel and radial vector measurement would have been greater. Do you have any idea why you can't get a perfect null with the DC coil activated? Can you achieve a null by adjusting current in the coil? PW

picowatt	Re: Grenade coil type systems « Reply #476 on: 2023-10-29, 21:39:14 »
Sr. Member Posts: 453	Quote from: Itsu on 2023-10-29, 21:28:08 Its possible to get 0mT with the probe in 0° position while 8A running through the coil, but its in another tilt position compared with 0A through the coil. Itsu, Does your measurement probe have a well defined/labeled measurement axis? I had assumed that the hall device was positioned in the probe such that one of the wide flat sides of the probe was one pole with the other pole on the opposite side. PW

Itsu	Re: Grenade coil type systems « Reply #477 on: 2023-10-29, 21:40:14 »
Group: Elite Experimentalist Hero Member Posts: 4159	Quote If I understand this correctly, the max field strength of the field parallel to the sausage axis with the coil deactivated is 171mT (seems low...). And, the max field strength when measuring the strength of the radial field produced when the DC coil is activated is 104mT. Is that correct? That is correct. Quote Do you have any idea why you can't get a perfect null with the DC coil activated? Can you achieve a null by adjusting current in the coil? I can, see my update on that above, but it takes time to position the probe which i do not have with 8A through the coil. Itsu

Itsu	Re: Grenade coil type systems « Reply #478 on: 2023-10-29, 21:49:50 »
Group: Elite Experimentalist Hero Member Posts: 4159	Quote from: picowatt on 2023-10-29, 21:39:14 Itsu, Does your measurement probe have a well defined/labeled measurement axis? I had assumed that the hall device was positioned in the probe such that one of the wide flat sides of the probe was one pole with the other pole on the opposite side. PW Well, not really, its denoted by a black dot and not right in the middle, so i try to put the dot in the middle of the gap and tilt it till it reaches 0mT, see: Itsu

picowatt	Re: Grenade coil type systems « Reply #479 on: 2023-10-29, 22:34:26 »
Sr. Member Posts: 453	Itsu, The reason I asked for those measurements was to determine the strength of the parallel field versus the rotated radial field. Another interesting measurement would involve trying to determine how homogenous the fields are. When nuclei with a net spin are placed in a homogenous B field, some spins will align like a compass would (lets call them spin up), some will align opposite to that (spin down). Spin up would be a low energy state and a majority of nuclei will be in that low energy spin state. If the B field is homogenous and stable, the nuclei will act as mini receivers all tuned to a specific frequency (the NMR frequency for that nuclei and B field strength). All of the nuclei will be precessing at the same frequency, but at random phase orientations. Injecting a little RF at a right angle to the B field and at the NMR frequency will cause all the precessions to become in phase. (Similar to the many videos of multitudes of metronomes eventually synchronizing with each other provided they are on a platform with some degree of freedom. The slight horizontal motion of the platform being analogous to the applied RF). By adding a bit more RF strength (or time) we can cause some of the spin down nuclei to flip and orient themselves spin up as well. At some point, spin flip saturation is reached, and no more spin down nuclei can be flipped to spin up. This is a high energy state. (For spectrometry purposes, the RF is then abruptly turned off and a receiver "listens" for emitted RF as the nuclei relax and return to their state prior to the applied RF) A non-homogenous B field causes all the nuclei to be tuned to different resonant frequencies dependent on the field strength at their location. Modulating the B field strength will also vary the resonant frequency. I suspect trying to turn the B field vector to a radial one at or near the NMR frequency will not achieve resonance due to the changing B field strength the nuclei will experience during the transition/field modulation. Perhaps NMR type resonance is not required for what Verpies has in mind. As I previously stated, I would have guessed that the field strength difference between the "parallel to the sausage vector" versus the "90 radial vector" would have been greater than observed. Perhaps the measured difference is also dependent on pole piece separation distance and measurement position within the gap. PW

picowatt	Re: Grenade coil type systems « Reply #480 on: 2023-10-29, 23:15:43 »
Sr. Member Posts: 453	Itsu, As a side note, I have often wondered if something like your VNA could be used to detect achieving NMR. Somewhat similar to using a grid dip oscillator, I would think one would see some measurable change in the RF drive signal when resonance was achieved. However, I do not know if that change would be too subtle to detect this way. Just food for thought... PW

verpies	Re: Grenade coil type systems « Reply #481 on: 2023-10-30, 00:15:09 »
Group: Moderator Hero Member Posts: 3499	Assuming that the probe's probe's A axis is perpendicular to the R axis and to the Z axis of the sausage, while the center of the Hall sensor (the red dot) is in the "middle of the gap" and somewhere between OD and ID of the ferrite rings, sliding on the R axis, like this: The diagram above depicts this, when the Z axis is poking you in the eye. Assuming that the 0° probe rotation also means that its C axis is parallel to the Z axis, and its B axis coincides with the R axis. Consequently, the 0° probe rotation is sensitive to the radial flux and insensitive to the axial flux. Assuming that the 90° probe rotation also means that its B axis is parallel to the Z axis, and its C axis coincides with the R axis. Consequently the 90° probe rotation is insensitive to the radial flux and sensitive to the axial flux. Quote from: Itsu on 2023-10-29, 21:04:44 probe position current through coil flux measured 0° 0A S 0mT 90° 0A S 171mT This is good. The 171mT might not be an impressive axial flux density, but it satisfies your cyclotron confinement radius. Quote from: Itsu on 2023-10-29, 21:04:44 probe position current through coil flux measured 0° 8A S 6.8mT (cannot get it to 0mT) This is wrong. The 0° probe rotation is sensitive to the radial flux, so it should read the maximum radial flux density, when 8A flows through the DC coil. Quote from: Itsu on 2023-10-29, 21:04:44 probe position current through coil flux measured 90° 8A S 104mT This is wrong. The 90° probe position is sensitive to the axial flux, so it should read the minimal axial flux density, when 8A flows through the DC coil (ideally 0mT). If the reading is high with the 90° probe rotation and 8A, then it could mean that there are too many or too few ampturns flowing through the coil to balance the magnet's flux ...and/or the coil is positioned a wrong distance from the gap.

picowatt	Re: Grenade coil type systems « Reply #482 on: 2023-10-30, 00:30:57 »
Sr. Member Posts: 453	Verpies, I was under the impression that Itsu's measurements were made with 0 degrees meaning his measurement axis was parallel to the sausage center line and that the 90 measurement were with the measurement axis perpendicular to the sausage center line (i.e., parallel to the radial vectors). Perhaps I misunderstood... PW

verpies	Re: Grenade coil type systems « Reply #483 on: 2023-10-30, 00:36:34 »
Group: Moderator Hero Member Posts: 3499	PW: If that was the case then the measurement below would not make sense: Quote from: Itsu on 2023-10-29, 21:04:44 probe position current through coil flux measured 0° 0A S 0mT Anyway, let him clarify.

picowatt	Re: Grenade coil type systems « Reply #484 on: 2023-10-30, 00:46:10 »
Sr. Member Posts: 453	Quote from: verpies on 2023-10-30, 00:36:34 If that was the case then this measurement would not make sense: Verpies, You are indeed correct... I was only interested in the two maximum readings (parallel flux and radial flux). The 171mT is the field strength with measurement axis parallel to the sausage axis and no DC applied to the coil, and the 104mT is the field strength with the measurement axis perpendicular to the sausage axis (parallel to the radial vectors) when DC is applied to the coil. (see reply 479) However, after rereading #475, I see the confusion as well... PW « Last Edit: 2023-10-30, 03:35:28 by picowatt »

Itsu	Re: Grenade coil type systems « Reply #485 on: 2023-10-30, 09:27:37 »
Group: Elite Experimentalist Hero Member Posts: 4159	PW, verpies, Quote Another interesting measurement would involve trying to determine how homogenous the fields are. The fields are not homogenous, as far as i can see as moving the probe from OD to ID shows many fluctuations. Also measuring a single magnet across its surface shows many different readings. Another problem is the positioning of the probe when probing inside the gap as we have many "degrees of freedom" to control. Quote Anyway, let him clarify. This picture shows me having the probe in what i call the 0° position: Quote This is wrong. The 0° probe rotation is sensitive to the radial flux, so it should read the maximum radial flux density, when 8A flows through the DC coil. Let me double-check on this as i am sure i found a 0mT spot with the probe in 0° position while running 8A through the coil. Itsu

Itsu	Re: Grenade coil type systems « Reply #486 on: 2023-10-30, 10:20:11 »
Group: Elite Experimentalist Hero Member Posts: 4159	Made a quick video to show the flux at 0 degrees with 0 and 8A running through the coil: https://youtu.be/Hh5ApHrmvc0 Itsu

picowatt	Re: Grenade coil type systems « Reply #487 on: 2023-10-30, 10:37:19 »
Sr. Member Posts: 453	Quote from: Itsu on 2023-10-30, 10:20:11 Made a quick video to show the flux at 0 degrees with 0 and 8A running through the coil: https://youtu.be/Hh5ApHrmvc0 Itsu Itsu, My confusion is with regard to which measurement axis you are calling 0 and 90 degrees. I thought the measurement axis of your probe passed through the dot or hole at its tip at a right angle to the probe's long axis. It appears from your video that is not the case. With the probe positioned as in the video, and the coil deactivated, is the probe positioned to measure the maximum field strength in the gap? PW

picowatt	Re: Grenade coil type systems « Reply #488 on: 2023-10-30, 11:27:57 »
Sr. Member Posts: 453	Itsu, Just in case you are not already doing so, when activating/deactivating the coil, ramp the current up and down relatively slowly. I would not hard switch the coil, particularly with the probe in the gap or nearby. PW

verpies	Re: Grenade coil type systems « Reply #489 on: 2023-10-30, 11:41:00 »
Group: Moderator Hero Member Posts: 3499	Quote from: Itsu on 2023-10-30, 10:20:11 Made a quick video to show the flux at 0 degrees with 0 and 8A running through the coil: https://youtu.be/Hh5ApHrmvc0 Are you sure the current in the coil generates an opposing flux when you make the second measurement? What you show on the video behaves as if the coil is generating an aiding flux.

Itsu	Re: Grenade coil type systems « Reply #490 on: 2023-10-30, 11:59:32 »
Group: Elite Experimentalist Hero Member Posts: 4159	Quote from: picowatt on 2023-10-30, 10:37:19 Itsu, My confusion is with regard to which measurement axis you are calling 0 and 90 degrees. I thought the measurement axis of your probe passed through the dot or hole at its tip at a right angle to the probe's long axis. It appears from your video that is not the case. With the probe positioned as in the video, and the coil deactivated, is the probe positioned to measure the maximum field strength in the gap? PW With the probe positioned as in the video, and the coil deactivated, the probe is NOT positioned to measure the maximum field strength in the gap. Measuring the maximum field strength in the gap is done with the probe in the 90° position Itsu

Itsu	Re: Grenade coil type systems « Reply #491 on: 2023-10-30, 12:00:32 »
Group: Elite Experimentalist Hero Member Posts: 4159	Quote from: verpies on 2023-10-30, 11:41:00 Are you sure the current in the coil generates an opposing flux when you make the second measurement? What you show on the video behaves as if the coil is generating an aiding flux. I double-checked, but it is generating an opposing flux as compared to the magnets as in this picture:

picowatt	Re: Grenade coil type systems « Reply #492 on: 2023-10-30, 12:18:23 »
Sr. Member Posts: 453	Quote from: Itsu on 2023-10-30, 11:59:32 With the probe positioned as in the video, and the coil deactivated, the probe is NOT positioned to measure the maximum field strength in the gap. Measuring the maximum field strength in the gap is done with the probe in the 90° position Itsu With the probe positioned as in the video, and the DC coil deactivated, what measurement do you get? PW

picowatt	Re: Grenade coil type systems « Reply #493 on: 2023-10-30, 12:43:22 »
Sr. Member Posts: 453	Quote from: Itsu on 2023-10-29, 21:04:44 verpies, PW, It takes some time (minutes) to position the probe on the correct positions which is OK with no power through the coil, but with 8A through it, i have only a minute or so before the coil heats up too much. But i was able to make these measurements with the probe in the middle of the gap: probe position current through coil flux measured 0° 0A S 0mT 0° 8A S 6.8mT (cannot get it to 0mT) 90° 0A S 171mT 90° 8A S 104mT Itsu Itsu, So in this reply, what you are calling 90 deg is with your measurement axis parallel to the sausage axis? If so, I believe it is that 104mT measurement that the DC coil is supposed to null close to zero. Can you make that reading close to zero by adjusting the current? PW

Itsu	Re: Grenade coil type systems « Reply #494 on: 2023-10-30, 15:01:32 »
Group: Elite Experimentalist Hero Member Posts: 4159	Quote from: picowatt on 2023-10-30, 12:18:23 With the probe positioned as in the video, and the DC coil deactivated, what measurement do you get? PW PW, you can see that in that same video as i start out with the DC coil deactivated, and the probe carefully positioned to read 0mT. So 0mT, but it takes some careful positioning to reach that with the probe tip in the middle of the gap halfway between the OD and ID of the core and the tip in the 0° position.

Itsu	Re: Grenade coil type systems « Reply #495 on: 2023-10-30, 15:32:19 »
Group: Elite Experimentalist Hero Member Posts: 4159	Quote from: picowatt on 2023-10-30, 12:43:22 Itsu, So in this reply, what you are calling 90 deg is with your measurement axis parallel to the sausage axis? If so, I believe it is that 104mT measurement that the DC coil is supposed to null close to zero. Can you make that reading close to zero by adjusting the current? PW Quote So in this reply, what you are calling 90 deg is with your measurement axis parallel to the sausage axis? Yes, this is measuring the flux parallel to the sausage (X) axis. Quote If so, I believe it is that 104mT measurement that the DC coil is supposed to null close to zero. Can you make that reading close to zero by adjusting the current? I probably could make that reading (104mT) close to zero, but i think i would need to put in (much) more current which i am presently not able to do. I made a similar video as this morning (0°), but now with the probe in the 90° position: https://youtu.be/k-DmhsWkxjk Same situation, but here i reversed the coil leads, so it now is in aiding mode together with the magnets: https://youtu.be/pHECjxOordI Itsu

picowatt	Re: Grenade coil type systems « Reply #496 on: 2023-10-30, 16:36:27 »
Sr. Member Posts: 453	Quote from: Itsu on 2023-10-30, 15:32:19 Yes, this is measuring the flux parallel to the sausage (X) axis. I probably could make that reading (104mT) close to zero, but i think i would need to put in (much) more current which i am presently not able to do. I made a similar video as this morning (0°), but now with the probe in the 90° position: https://youtu.be/k-DmhsWkxjk Same situation, but here i reversed the coil leads, so it now is in aiding mode together with the magnets: https://youtu.be/pHECjxOordI Itsu Thanks for doing all that Itsu... This makes more sense to me now. As I stated earlier, I suspected that the radial measurement would be quite low compared to the no coil parallel field measurement. When the parallel field is nulled with the DC coil (you need a bit more coil or current to accomplish that), the measurable radial field will be quite low (somewhat similar to summing a common mode signal). As the lines of force exit the pole pieces they make a right angle turn and the lines become radial to the sausage axis. Under those measurement conditions, there is no "south pole" per se, only a field strength gradient along those lines. Rotating the probe a bit or moving it around in the gap will net slightly larger field measurements, but the measured strength will remain significantly lower than the non-energized parallel field reading. Because of this, when the HF coil is activated as planned, there will only be a small amount of torque applied to the nuclei. In some areas, where the field lines have not yet become parallel to the pole pieces, there will be an increased gradient causing them to tilt a bit, but in your measurement position (somewhat centered in the gap) there will be little force applied to the nuclei to cause their spins to follow the radial field. PW « Last Edit: 2023-10-30, 17:49:18 by picowatt »

verpies	Re: Grenade coil type systems « Reply #497 on: 2023-10-31, 01:55:25 »
Group: Moderator Hero Member Posts: 3499	Quote from: picowatt on 2023-10-30, 16:36:27 ...I suspected that the radial measurement would be quite low compared to the no coil parallel field measurement. When the parallel field is nulled with the DC coil (you need a bit more coil or current to accomplish that), the measurable radial field will be quite low (somewhat similar to summing a common mode signal). I don't understand the analogy to the "common mode signal". Overall flux cannot be "nulled" because flux lines do not subtract nor cross each other and always form closed loops. They cannot be made to disappear, they can only be bent (that can only null one component of flux density in one direction). The only way to get an overall lower flux density is to distribute it over a larger volume.

verpies	Re: Grenade coil type systems « Reply #498 on: 2023-10-31, 02:25:46 »
Group: Moderator Hero Member Posts: 3499	Quote from: Itsu on 2023-10-30, 15:32:19 I made a similar video as this morning (0°), but now with the probe in the 90° position: https://youtu.be/k-DmhsWkxjk Same situation, but here i reversed the coil leads, so it now is in aiding mode together with the magnets: https://youtu.be/pHECjxOordI You will find high radial flux density at larger coordinates along the R axis (further from the Z axis of the device) beyond the OD of the ferrite. However at this distances the axial flux density suffers, so I will have to think of a better field geometry to maximize both.

Itsu	Re: Grenade coil type systems « Reply #499 on: 2023-10-31, 15:10:32 »
Group: Elite Experimentalist Hero Member Posts: 4159	In this last setup i found a way to put 15A through the coil for a moment and the flux dropped to 70mT when in the 90° position (middle of the gap, middle in between OD and ID). So this updates that part of the table to: probe position current through coil flux measured 90° 0A S 171mT 90° 15A S 70mT Measuring the flux density with 1A steps through the coil (till max 8A then adding the 15A value) shows this data and graph: So if i would imagine the trend line, it would take many more amps to reach zero mT Coil is 530 turns of 0.8mm magnet wire (88m) with a measured resistance of 3.5 Ohm. Itsu

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