402T

SRM BOX Field Trap, Measurements, and Experiments

At the BOX the SRM drive belt was complete loose with the tray pins also too wide and dropping the string and as the belt was skipping off the drive gear and not consistently advancing. The pins and the belt tension were adjusted and seems to be advancing correctly.

The field was measured and was within specs, how every the tray noise seemed a bit higher than usually. The a better field was trapped and the noise dropped from 10-6 to 10-7 in intensity.

Exp 401

SRM BOX Field Trap, Measurements, and Experiments

At the BOX, the SRM null-field was trapped and the profile was only  +/- 1nT in the SQUID region. The SRM AF Degauss coils were tested at 40 mT and all measured within spec to a few percent (see figures below).

The SRM was used extensively throughout the expedition for both discrete samples and archive SHLFs. The biggest issue was with flux jumps, since the samples were typically very weak. For the reason, the "Pause and Confirm" in the SRM IMS was vital. When an Outreach & Education tour was happening, they would give a 15 minute warning to us, and we would put the SRM in pause and confirm mode, and continue to measure. After each measurement, the data was inspected for flux jumps and immediately remeasured if there were issues. If (or once the data was clean), the data was saved and the next sequence was initiated. This allowed measurement to typically proceed with minimal interruption and no lost data due to flux jumps. The science party itself caused plenty of flux jumps and all SRM data was screened, inspected, and then deleted from LIMS (via LIME) when necessary adding hours of unnecessary work and data loss. If the samples are weak and flux jumps are common fro the science party, then the SRM can be run in same manner, but this requites someone to be constantly at the SRM computer inspecting and reacting to the data.

Exp 400

SRM BOX Field Trap, Measurements, and Experiments

When measuring the SRM internal field at X400 BOX, it was noticed that DAFI was entirely not working. After open NI-Max, it was apparent that the alias for the USB-6008 was incorrect, and once set back to “DAFFI” worked correctly. However, the IMS changes to the DAFI output on 397T were also lost, and the SRM frame of reference (FOR) columns were incorrectly order and had the incorrect order or magnitude.  Hopefully this can be fixed this exp with help from the developers, but for the time being was just manually corrected.

The initial SRM field profile was about an order of magnitude too high in the SQUID region (peak ~80 nT) so a re-trap in port was necessary. After re-trapped the field was within +/- 2 nT at the SQUID sensors. It should also be noted that the apparent position of the Z minimum is always advanced by ~ 2cm since the Z sensor is about 1 inch before the Y and Z sensors.

The AF degausser coils (strength, position, and response width) were measured 40 mT field with the hall probes, and are within about +/-5% of the desired values. Since the field near the edges of AF coil region are rather high for the Z axis. Since is concern for potentially imparting ARMs during demagnetization and this concern has been express at various point over the past years, the AF coil response functions are plotted by position along with the SRM field profile over this region (Figure ###). Also included in this plot are the relative sample directions for each demag axis.  Fortunately, the geometry was well thought out (one assumes) and even if samples see large perpendicular Z fields in the respective coil response regions, the sample ends the demag cycle in the lower field region. Furthermore, only slight FOR misalignment between coils and sample result in parallel components and will be small and result in little to no ARM. The Z demag happens in the minimum of the Z field at ~ ### nT, and since the Z axis has the largest noise in general, it’s unlikely that the small resulting ARM will even be observed, or at most as a slight bias to the noise. 

Lisa Tauxe is sailing at the lead Pmag scientist for X400 and immediately expressed concern about a common misalignment in 2G systems between the SQUID FOR and the sample tray FOR resulting in a constant shift in declination. If this were the case, then it would help resolve the seemingly nearly constant and prevalent shift in declinations derived from the magnetic orientation tools (MOTs). After some measurements of standards measure and prepared by the Scripps Institute of Oceanography (SIO) as well as by Oregon State University (OSU), it looks like there is good agreement and that there is not a shift in declination. This is obviously good for the lab’s data but does not offer an easy explanation to the MOT declination issue.

Paleomagnetic Standards

Two sets of standards from SIO and our inhouse standards were measured on both the JR-6 and SRM for cross comparison between the 2 systems as well as one of the SIO sets that was measured both by SIO and OSU. I general there is good agreement between all standards and measurement equipment as well as institutions and most slight discrepancies are likely related to sample positioning errors. It seems best to measure each standard 3 times but take the sample out of the instrument and re-insert every time to help get a better average out positioning errors. One slight disagreement between measurement was that the JR-6 and SRM intensities showed diverging values, appearing to have larger difference with increasing intensities.

There were issues encountered with the sample uploads including MUT not being able to upload the known QAQC standards and then newly created standards were entered into sample master as 999 samples successfully, but also would not upload with MUT.

Also, the SIO standards were prepped as archive half samples and initially caused confusion for running on the JR-6 and SRM. For the JR-6, an archive discrete is inserted with the hash arrow into the holder (still point up and to the left) and the X arrow is now towards the user. Values of 0 and 90° are still used in the software for azimuth and dip to convert from sample FOR the geographic. For SRM, and new discrete archive top-away preset was made to accommodate the samples.

The Pmag PlayCubes were given the typically 30 mT IRM, place into the foam tray in the SRM in various orientations, and then subjected to stepwise demagnetization. All samples showed correct orientations and demagnetized as expected

EOX Shutdown

Since power will be off for some extended time period during the tie up, the SRM and all peripherals were shut down at the EOX.

EXP395

-Discrete Standards would not scan into the SRM due to a sample type mismatch.  Noted that in the Label Scan Parse.vi in the YES case the Info Type was hard wired to be 'SECT'.  A case was added to the code so that when a sample type= CUBE, the Info type is discrete-W and the default for other standards is still SECT.  Image below shows the case added inside the Yes case.  no changes were made to the NO case.  This is a change to an IMS common vi, so it could have consequences to other code.

A small change was also made in the Get Values with Sample Number from Scanned String.vi in IMS common.  In the Standard case the Working ("W") case contained an output for info type as Discrete-A.  This was changed to Discrete W.

Exp 398P

• SRM offline treatment 'looping' issue was addressed.  In the SRM DAQ Engine.vi Pass Scan Process case, the true and false cases both had a value of zero as the output. True case is for a user abort while the false case is supposed to be normal operation.  We rewired the False case to use the 'Action Index out' value output from SRM DAQ Engines Stop.vi.  This stopped the looping behavior when the offline treatment window opens.

SRM DAQ Engine.vi block diagram with the correction made in the false statement within the pass scan process case.

• We noted offline treatment files included some file writing issues. We updated the SRM Extract Treatment Data. vi to correct the file writing.
  • If the user selected a treatment type of ARM, PARM, AFDemag, or IRM, the field used value was always 0.   The cases were all extracting Field Gauss from the sequence action and dividing by 10 to convert to mT to produce the final treatment value.  But for offline treatment, the values are entered in a separate field.  We changed the cases to pull treatment value from the correct field (Sequence Action: Offline: Axis Used. Field Gauss) and we removed the division by 10, since users are entering values in mT, not gauss.  

SRM Extract Treatment Data.vi with the division by 10 removed and the updated 

• • The treatment values were also being written as treatment_value= 5.0000,5.0000,5.0000, but this causes issues at upload. We have not had a time where a user does variable treatments for a single measurement.  SRM Extract Treatment Data.vi was modified to only write the treatment value once in treatment_value.

SRM Extract Treatment Data.vi before edit- This incorrectly wrote the treatment values and wrote the treatment values 3 times to the file (one for each axis). The treatment for each axis was being concatenated into 1 string.  In this version x-value= 5.0,5.0,5.0.  After the edit, x-value=5.0

• ISSUE: Background files contained incorrect treatment data.  The sequence action data structure and the SRM private data structure both contain this information, but were not both properly written to.  When the code tried to pull the treatment information it was getting old information.  In the SRM DAQ Section Tray Clean and Bkground UI.vi and the SRM DAQ BKU Line of Data.vi  case structures were added to pull the correct information at the time of background measurements and updae the SRM DAQ Data structure.  

Changes within the SRM DAQ BKU Line of Data.vi (pull sequence information from srm daq data and if the action is a background, use the action from SRM DAQ Data, otherwise use the sequence action data structure.

SRM DAQ Section Tray Clean and Bkground UI.vi changes all done within the case structure BKGD ONLY, DEFAULT (all cases) to pull the correct treatment information for the background file.

Exp 398

Something

Stuff

Something else

More stuff

Exp 397

SRM Degausser Alarm

An alarm, called the SRM Degausser Alarm, was installed after the coil runaway incident. The alarm connected to the Degausser controller unit is based on the duration the "Ramp Up" and "Tracking" LEDs are on. A Confluence page about the SRM Degausser alarm was created and is found here: SRM Degausser Alarm.

SRM weaker shield or lab limitation?

QAQC IODP cube standards were measured on the SRM for QAQC statistics to set maximum and minimum boundaries in QCViewer. During a measurement sequence of 10 NRM, standards with negative inclination were showing positive inclinations for a few NRM measurements. The measurements were repeated and IODP cube standards with negative inclinations, namely IODPSTD03, IODPSTD04, IODPSTD05, IODPSTD08 and IODPSTD10, were measured 50 times to check why some NRM measurements were giving positive inclination values. IODPSTD06 and IODSTD07, with positive inclination, were chosen as control samples. It appears that drastic changes happen on the Z moment during some NRM measurements and affect all samples in the tray with more noticeable effect on the standards with negative inclination.

Meanwhile, when measuring AF demagnetization at 20 mT on archive sections, scientists notice that some sections were showing steep inclination (close to +/-90°) like if they were "remagnetized" (ARM-like behavior). A second demagnetization run at 20 mT gave different values (see screenshot below). This happens on many XCB sections from Sites U1587, U1385 and U1588. It was noticed that a scientist (core describer) had a phone in use NOT on airplane mode next to the SRM. This might explain the strange data obtained on our standards and on weakly magnetized material like the sediment material recovered during Exp 397.

Measurement 1 is showing steep inclination values ("remagnetized-like" section), Measurement 2 in agreement with the NRM and general trend of the core. Data shown here are from Core 42X of Hole U1587A.

Because of the coil overheating incident, the first thought that came in mind is that the SRM had again issues. Mark did a field profile and noticed that the peak at ~350 cm was back (see below when the coil incident happened). He released the flux and trapped the field. The field profile after trapping was better. Time Series Utility was run for about an hour but nothing obvious was noted. We used the Hall probes and the gaussmeter in DC mode to check whether a particular field was present which may have caused a remagnetization of the sections during the degaussing phase. Field values outside and inside the SRM were identical (6.3 mT for Z, 9.36 mT for X and 9.3 mT for Y). Running an AF demagnetization at 20 mT manually changed slightly the values during the ramp up/tracking/ramp down sequence with values between 6.1 and 6.6 mT for X, 9.1 and 9.6 mT for X, and 8.9 and 9.6 mT for Y.

After verification of the data and demagnetization at intermediate steps (5,10 and 15 mT), it appears that the sediment material measured is very weak and in the order of the tray background. It is possible that the AF 20 mT demagnetization step is too high to get reliable results at the investigated sites. Detailed AF demagnetization with D-tech on discrete samples from sections showing steep inclination show that even measured with the JR6, discrete samples do not show good data, and that the material gets demagnetized at low AF field values.

The most likely explanation for the steep inclination on archive sections is that the material is too weak to be measured with the SRM and measurements are potentially reflecting flux jumps happening because of use of wifi, elevator motion, amplifier in the core lab, etc... These flux jumps seem not to be recognized by IMS. A massive flux jump was observed when scientists were changing settings to the amplifier located right in front of the SRM. Particular attention should be paid around the SRM when weak material is measured, especially cell signal must be turn off, i.e., airplane mode must be turn on. A scientist had a phone NOT in airplane mode in the lab next to the SRM.

The hypothesis of weak material sensitive to small flux jumps may stand also for the IODP cube standards which have lower magnetization and negative inclination.

Another observation made by the pmag scientists is that when there is a flux jump (on the Z axis) during a tray background measurement not noticed by IMS, this has consequences on the correction of the measured moments, leading to the steep inclination ("remagnetized-like" behavior) of some very weak sections measured.

Recommendations (already known) to future lab user:

• make sure that all electronic devices are on airplane mode
• check for any suspicious background values when inclination is steep
• be aware that very weakly magnetized material may not be interpretable, especially XCB material

Degausser X-Coil Overheating (Oct. 24-25, 2022)

Oct. 24 

• At ~18:30 an AF demagnetization at 80mT was run on the empty discrete tray in preparation for measurements.  The scientists continued measuring the tray, first at another 80mT step but that sequence was aborted.
• The scientists continued to measure NRM only.
• At ~20:00 UTC a burning smell was noticed in the core lab.  Eventually smoke was noticed coming out of the small holes in the endcap of the degausser section of the SRM.  The shielding of the degausser section was very hot.
• The degausser control unit and amplifier were shut down and eventually the power completely isolated.  The Cryomech compressor was also shut down out of an abundance of caution.
• The Siem officer on watch was notified and a fire watch and electrician were sent to provide assistance and assure no further risk of fire.
• With the assistance of the Siem electricians, the low field region of the SRM was removed in order to remove the endcap shielding of the degausser section to inspect the coils for any sign of fire risk.
• A Flir camera was used to measure the temperature of the coils and the X-coil measured at 180 degrees C at first inspection. The coating around the X-Coil is black and likely the material that burned and caused the smoke and smell.
• Wet rages were used to cool the outer shielding and coil.  Fans were mounted to circulate air through the degausser and the temperature decreased.
• Once the situation was under control the resistance of the three coils were measured (X=10.8 ohm and very hot; Y= 9.4 ohm; Z = 12.6 ohm) and compared to values taken before. The values were higher for the X and Z coils but they were still hot.  

Flir camera (left) showing the X-coil temperature (in the back on the picture on the right) at 175°C

Oct. 25

• Coils were allowed to cool down and by 01:30 UTC were down to 30 degrees C.  The resistance was measured on the three coils: X= 8.6 ohm; Y: 8.5 ohm; Z=10.9 ohm, which are expected values for the three coils.
• ET inspected the relays in the gray high voltage box. With the coils disconnected, the relays were tested with the degausser controller and function as expected. 
• The electronics in the degausser control unit were inspected and the power cable for the serial communication interface board was secured.  No major issues were  noted within the degausser controller.

• The degausser coils were tested with the Hall probe with the track still disassembled. We manually placed the hall probe in each coil and took readings.  All three behaved as expected when the coils were properly positioned.

  	20 mT	30 mT	40 mT	50 mT	60 mT	70 mT	80 mT
  X coil	19.93	29.69	40.16	49.91	59.81	69.85	79.61
  Y coil	19.68	29.40	39.39	49.07	59.11	68.72	78.34
  Z coil	19.51	29.41	39.59	49.49	59.81	69.43	79.33

• At 01:30 UTC the compressor was restarted to cool the SRM down and maintain vacuum. By 07:00 the temperatures were down to 5.2 (TSH) and 4.6 (TSQ) then at 12:00 were 4.8 (TSH) and 4.6 (TSQ).
• The track was reassembled.   We had to modify some brass screws to ensure the tray would not catch on them as it passes through the SRM. Pass through tests were completed and there were no issues noted.  A write-up on track assembly will be done.
• A position test was performed and the positions were accurate.  The end of track switches functioned properly.
• With the track assembled, Beth manually triggered each coil using the Degauss Controller Auto Ramp feature at 20 mT.  The coils all responded appropriately.  The test was done again using the IMS Degauss Utility to ramp up to 20 mT and ramp down, all responded properly.  The time out was tested on the Y-coil at a low field and the software was able to tell the coil to ramp down properly without any user input.
• A field profile was run with the Fluxgate revealing extreme fields in the area between squids and degausser at offset 350 cm, up to 600nT on the Z-axis.

• After 12:00 local time (11:00 UTC) , a new field was trapped. The field profile was again measured and the high field at 350 cm was no longer present.

• The field profile at 10 mOe was measured and compared to the field profile measured before the incident at the beginning of the expedition on October 16, 2022.

• Two X397 sections were measured to compare their values with the values at 20 mT obtained before the incident. Values are comparable. Sections from an interval correlated with Hole A's data were measured and data looked good. Therefore, scientists kept running sections for NRM and AF demagnetization at 20 mT.
• There is still a noticeable burning smell coming from the degaussing section of the SRM when the degausser is used, currently only at 20mT.   

The likely culprit and what we are doing

• During testing it was noted that when the user aborts during a degauss step the software appeared to freeze with the abort window displayed and the degausser still in tracking mode.  The software abort sequence did not communicate to the controller to ramp down or give the user the option to ramp down which it is believed the software used to do, thus the controller kept applying current to the X-Coil that would have been the first coil to be ramped up in the degaussing sequence and was on when the abort button was clicked.  
• It will be critical to monitor the LED indicators on the controller, especially during degaussing sequences and especially if the software abort button is clicked.
• If the tracking light is on and an active degauss step is not in process, turn the amp to 0 and turn off the controller, at which point no current will be applied to the coils. It may be necessary to shutdown the main power supply (grey high voltage box) by unplugging it.
• The IMS software will need to be looked at carefully as the abort feature used to work correctly.  Testing will be done as time available. Updates: Tests were done after the IMS code was corrected, however, great care should be taken when a sequence is aborted.
• Alarm system similar to BuzzBox (used to check the cooling water temperature) will be implemented to alert when the temperature inside the shield gets higher. Updates: a SRM Degausser Alarm based on degausser LEDs being on/off was installed on November 18, 2022. See SRM Degausser Alarm for details.
  
• Applied Physics Systems has been contacted to ask their opinion on if they think any damage has occurred and if so, what should we look for. Updates: Dave Schuler on October 26 [The biggest danger in overheating is damaging the coils and causing a short.  By your test, it looks like you avoided that.  You should be okay, but I recommend having someone nearby for now when you are degaussing, just in case.  A temperature alarm or emergency cutoff might be an idea for you guys.  The coating on the coils is Stycast 2850FT.  I dont think you will need to recoat it, but you could reach in and touch it and see if it is soft or crumbling to make sure.]
  

Monitoring of the SRM after the coil overheating incident and work on IMS code

• SRM degausser was monitored over the following days of the event. The degausser lights appear to work properly when running a sequence of NRM+AF demag at 20 mT on sections.
• Smell is sometimes present in the lab but less strong than before and will dissipate with time. The smell may still be present for the next expeditions when the coil is in use.
• The frozen ABORT window was due to a bug in the IMS code which was fixed by Beth. Tests conducted after this fixing were successful, and the ABORT window and associated actions work properly.
  

Other remarks

• A new format for the small "pmag cube" label to be scanned with the IMS-SRM code was deployed. The old labels were no longer accepted with the new IMS code when they were scanned. The "pmag cube" label was therefore modified to match the IMS-SRM code. The new labels were tested with the JR6, the MFK2 and Gantry successfully. The "pmag cube" format in Sample Master was deployed with changes made to match the SRM sample information entry. It has to be noted that following this change the small QAQC labels on the IODP standards cubes are not working anymore. Use the large labels with the "Sample Table" format instead.
• Uploader MUT2 now used to upload SRM data to LIMS
• LORE Expanded Report for the SRM was modified with unused/obsolete columns removed.
  

Exp 397T Transit/Return to Walvis Ridge UNDER CONSTRUCTION 10-18-22

Note: Big events from X397T are to be listed here!! Roth set up JRVPN 10-18 to start finishing updates.

Restarting the SRM Computer

The first time IMS was started on 397T, there was a problem with IMS initializing the SQUIDs. Power cycling the the SQUIDs and restarting the computer seemed to fix the situation, but did not solve the problem as it has been reported prior to this. The error report was given to the developer to investigate (IMS-SQUID Error- X397T).

Immediately after this, it was noticed that both Cyrowatch and the SRM Alarm program (BuzxBox) appeared to be function correctly but were not correctly reading/writing the log file. This was a path issue because the user account's root directory is now "daq.SHIP" instead of just "daq". The path has to be manually changed every time that the programs are opened. Ideally this would be changed in VI files (as well as the COMs default) but there is a licensing issue with Cryowatch and missing Unix/Linix/Ardunino LV module with BuzzBox and neither programs can currently be recompiled.

Because of the previous two situations, a very explicit SRM computer startup protocol was written until the SQUID issue is resolved and the programs can be recompiled with the corrections. It should also be noted that this path issue could show up else in the labs in general and when a program is having an issue, it should be investigated early in the diagnosis of the problems. 

When the SRM computer is rebooted, there are currently several steps that need to be performed each time to ensure that the IMS and the SRM peripherals are all functioning correctly. While the cause of IMS not always successfully initializing the SQUIDs is unknown, the issues with the Cryowatch and BuzzBox programs are well understood and just errors with setting the COMs and file paths.

IMS Utilities

IMS 13.0 was rolled out at the end of 397P so all of the utilities need testing. At the time DAFI was know to not be recording nor displaying data,  but after B. Mills fixed a few strings in the DAFI VI, it was successfully displaying and recording data, but it wasn't clear if the data was correct. The SRM internal field was measured with the Fluxgate by manually recording the values and then again by using DAFI and they agreed near perfectly. Since DAFI uses the USB 6008 Utility, it seems safe to say that this utility is also functioning correctly. MagSpy and the Time Series Utility were also both was working correctly and when the heading info was being provided, they both properly displayed this as well.

(Two notes about the FluxGate: Box B seems to be reporting off values with the Y axis and was verified to be the box and not the probe as all combos were tested, but further testing is need.

hhlkhl

Tray flags

IMS -DAFI, MagSpy, U-Turn DAFI compare with manual measurement.

397T BOX internal field. Zeroing fluxgate. Fluxgate Box B. Degausser measured. Backgrounds

Degausser Failed repairs, remeasured. leave covers on (change in user guide) Switched back to the QSC amp (spare)

Major trapped flux. New field trapped. repaired broken solder joint.

O-scope signal pulsing.

Flux afterwards and waiting to see if it disapaits.

SRM track alligned. tool Marking, shimming, testing.

(Very) Detailed information is found be in the Confluence page of the Super Conducting Rock Magnetometer (SRM).

 Exp 397P Tie-up

Note: Big events for the SRM during the tie-up: Workstation change, new IMS program, and instruments got issues. Most are fixed for the time being. The issues are presented below from most recent to older ones.

• User's manual for the degaussing system and Operating Manual for the SRM were received from Dave Schuler. The manuals are found in the Instrument Resources>Vendor Documents (right panel of this page) and in IODP_Share>Pmag>Pmag_Documents>SRM

Background noise after "SRM repair"

Final background noise check for the tie-up was checked on September 7, 2022 with three consecutive measurements of empty trays (BLANK). Average DBC moments are 1 x 10^-12 Am² for X, -5 x 10^-12 Am² for Y, and 6 x 10^-12 Am² for Z. Data of the plot below are found at IODP_Share>Pmag>SRM Cape Town 2022>Data BLANK.

DBC Moments of empty tray measurements (Sept 7, 2022)

Degausser Controller/Amplifier issue

After the SRM was put back together and cooled down to the superconducting state, issue with AF demagnetization happened - no tracking, the field kept ramping up when the first AF demagnetization computer-controlled (IMS) was set. We switched to the Manual mode of the degausser controller to check whether this was an IMS code issue due to some Windows updates performed the day before on the SRM computer.

Unfortunately, the issue (no tracking/keep ramping up) continued in the Manual mode. After checking the continuity of the cables which connect the coils/SQUIDS to the power supply (big shielded cables connected to the end of the SRM), the issue persists. The problem appears to be completely random. It could be one coil at a time which is not tracking (whatever the coil is) or two coils at the time which is/are not tracking/ramping down. The tracking light did not turn green, or flickered (completely randomly, too). Other times, all coils were tracking and ramping down. There is no consistency in the observations. Switching back to the Computer mode of the degausser controller showed the same inconsistencies.

We kept trying the Manual and Computer Modes by turning on/off degausser and amplifier many times, restarting the computer/IMS because IMS needs to be reset when an error happened in the AF demagnetization steps. Many communication errors with SQUIDS or degausser occurred with IMS every time we tried with the Computer mode (IMS Degauss Utility used). At the end of the day, we could manage to have X and Y coils working (ramping up → tracking → ramping down) and Z coil not working.

The day after (September 6), the axial Hall probe was set to check if the Z coil actually applies a field or not. The test was done at 200 Gauss (=20 mT). When the tracking light for Z is flickering and then working fine (i.e., ramping up → tracking → ramping down works great), the teslameter gives expected values of around 15.8-15.9 mT (which corresponds to 15.8 x 1.414 = 22 mT after applying correction factor). When the tracking light for Z is not working (completely off), then the field keeps ramping up. Flickering or no flickering is random. We switched to the spare amplifier as our last resource and used the Hall probe for Z. Same observation as before: when tracking light flickers and becomes static/solid, the values are good between 14.8 and 15.8 (depending on the position, average around 15.0 mT which yields a value of 21 mT after correction). When the light was flickering, we could also observe a flickering signal light on the front of the amplifier. This observation suggests a communication/power supply issue in the degausser controller.

We opened the degausser controller to check the inside and see if there were any disconnected, loose or burnt wires. Everything seemed normal, we touched some connections to see if they were loose, maybe some are. We connected it again to the spare amplifier. The fuse located at the back of the degaussser controller (see picture below) was removed and put back in. We checked again with the Manual mode and the ramping up → tracking → ramping down sequence worked perfectly for the three coils. We tested the Computer mode with IMS (Degauss Utility) and it worked great, too.  We finally ran our last check which was to use the transverse Hall probe to see if there is a field applied on X and Y axis. The values obtained are a maximum of 14.7 mT (i.e., 20.2 mT) for the X coil at 246 cm, and 14.1 mT (i.e., 19.9 mT) for the Y coil at 280 cm in the SRM. These values are very good and the SRM seems to be back to normal operations. The spare amplifier is now the one in use in the lab.

Connections behind the "spare" amplifier (in use from now on) and the fuse (red square) to check

As of the time of this report, we are still not sure why this issue with the degausser/amplifier happened and what caused it.

SRM noise and background: David Schuler's visit 

David Schuler from Applied Physics came onboard the JR from September 1 to 5, 2022 to check the status of the ship SRM and fix an increasing-over-time background level (see Expedition 393 notes below). After unlocking the signals of the SQUIDs, David Schuler suggested that the X- and Z-axis coils were not reaching a superconducting state (oscilloscope signal was not static and sinusoidal) and that some interference may cause the observed noise. The Haskris water chiller and compressor were turn off. Signal became better when the compressor went off. The SRM was disassembled the same day and warmed up so we could check the inside the day after. 

On September 2, the SRM was warm (T=300K) and the vacuum was cracked. A vacuum leak of the SRM has been ruled out by Dave Schuler because we would have had a higher pressure when the vacuum was cracked. The SRM was then open and the radiation insulation was removed. The SQUIDS connections were checked by Dave Schuler. No connection was broken, nothing obvious was noted, but some cables were close to each other and were rearranged. The outer radiation shield was off centered (lower than center) and some rubber was added below to lift it up. This might be the cause of the increasing noise with time.

After checking the SQUIDS connections, the multi-layered radiation insulation (MLI) was put back and the shield closed. The SRM was put back all together. The roughing pump was used to set a vacuum then replaced by the Hi Cube turbo pump.

Pictures of how the SRM was disassembled and of its inside, and a Word document (thanks Beth !) and PowerPoint showing the major steps of disassembling and fixing are found at IODP_Share>Pmag>SRM Cape Town 2022.

On September 3, Dave concluded that the vacuum was good enough and the valve was closed with a final pressure of 1 x 10^-3 hPa. If we had extra time, it would have been better to wait longer to probably get a lower pressure. The turbo pump was turn off, Haskris water circulation and compressor were turn on to cool down the SRM to the superconducting state. On September 4, the superconducting state was reached and we waited for the SQUIDS to be at equilibrium. On September 5, Dave Schuler came on the JR to check the background signal. The locked signal was very good on the three coils . 

An empty tray was measured (NRM) but AF demagnetization did not work. The X coil was not tracking and kept ramping up in IMS. See above "Degausser Controller/Amplifier issue" for more information.

The issue with the degausser controller did not prevent empty tray measurements (NRM only).

Workstation change and new version of IMS

• Workstation (PC) change with new version of IMS (version 13). New workstation is SRM (#54142).
• Cryowatch has a different com port. It is now #7. 
• IMS software issues: Many issues getting/retrieving sample information when scanning a label or using the LIMS tab. More issues with the code were identified (e.g., drift/background correction, no data writing in the .SRM file, wrong calculation, column headers, etc...) and debugged with Bill Mills to measure archive half section. A document detailing the different issues encountered with the new IMS code is found here. Many days were spent to debug the IMS code for the most used sample presets. As of September 4 2022, the IMS code and data output were tested and confirmed for section halves (both archive and working) and discrete samples in position Working half Top-Away (WTA). A document explaining the different corrections and rotation applied to the raw SRM data is found here and at IODP_Share>Pmag>Pmag_Documents>SRM.
  
• IMS: Other sample presets (e.g., WRND, u-channels) and other SRM utilities (e.g., U-turn, time series, etc...) have not been tested and will be during the transit to Lisbon (Expedition 397T). DAFI is not working at the time of this report (output moments are zeros).
  
• MagSpy, program associated to IMS, needs to be tested during transit, especially the communication between the SRM and the navigation program (Navipac and then IRIS) to confirm the ship heading which is recorded in the .SRM datafile generated.
• Excel spreadsheet for calculating corrected moments and intensity, declination and inclination from the raw SRM data has been created after Gary Acton's original spreadsheet. This new spreadsheet (SRM Data Calculation Spreadsheet_2022.xlsx) only valid for archive section half, is available at IODP_Share>Pmag>Pmag_Documents and in the Instrument Resources (right panel of this page).
  

• Wire for the Y-axis coil in the little blue box below the SRM for checking the field got disconnected because of bigger cable wiggling. Wire was welded and the big black cable was secured. 

Disconnection of a wire for the Y-axis coil and black cable secured after repair

 Exp 393

• The statistical analysis of the backgrounds and the SRM internal field measurement will be done in port after the deadline for this instance of Confluence is made available to the shore.
• Follow-up of comment above by Myriam Kars at BOX 397P:

Field profile inside the SRM performed by Alex Roth in port at EOX 393

SD versus time at EOX 393 (plots by Alex Roth)

Exp 390

• After measuring the field profile inside the SRM, SQUIDS were heated up to 10K and the field trapped. Field trapping was done on April 12, 2022, in Cape Town shortly after leaving port for Expedition 390 Site U1556 (Figure 1).

Figure 1: Field trapping at the beginning of Expedition 390 in Cape Town

• Wifi has been known to create additional noise in the SRM (see Shanghai assessment). During a test broadcast, an high disturbance noticed by J. Dinares-Turrell happened in a running tray background measurement when EO officer approached the SRM with connected Ipad (Figure 2).

Figure 2: Response of the SRM background when there is a broadcast in its vicinity

Paleomagnetist J. Dinares-Turrell performed tests with his smartphone and wifi on at varying distance from the SRM. His device connected to wifi - even with air plane mode on – creates higher noise in the SRM, at a distance of 2-3m. This particularly has importance if core describers at the description table have their phone on wifi. Science party, especially core lab users, have been informed about that. New information signs on Core Lab doors were put.

• The noise level on the X and Z axis still persists during X390. Comparison tests between SRM (time series) and Mettler-Toledo balance from the PP area of the Core Lab were performed to check the influence of the ship motion. First test was conducted by Mark Higley on April 14, 2022 during transit (Figure 3).

Figure 3: Comparison between SRM moments (top) and Mettler-Toledo weighing (bottom). Acquisition time is 150 seconds. For the SRM, 22 waves in 150 seconds = 0.147 Hz (6.8 second period). For the M-T balance, 25 waves in the same 150 seconds = 0.167 Hz (6.0 second period). Frequencies are similar but do not match perfectly.

• Second comparison test was conducted by Alejandro Avila and Myriam Kars on April 18, 2022 during transit (Figure 4) - note: sea was rough. 

Figure 4: Comparison between SRM moments (bottom) and Mettler-Toledo weighing (top). Acquisition time is 300 seconds (=5 min). For the M-T balance, about 44.5 waves so ~0.15 Hz. For the SRM, 34.5 cycles for 286 seconds so ~0.12 Hz for the SRM

• We investigated with the fluxgate the noisy parts/potential devices with magnetic disturbances and found that the high voltage unit next to the entrance of the SRM has great influence. We tried to shield the entrance of the SRM with a piece of mu-metal and run a time series and field profile. Nothing pertinent. It might be good to retry this with a much better shielding of the entrance of the SRM.
• During measurements of hard rock pieces with the SRM, anomalous flux jumps on the Y axis happened at about 50 cm. After AF demagnetizing the tray and cleaning, jumps still persist. Flipping the tray to bottom/top did not change the offset of the flux. After a few times of cleaning, the jumps disappeared. It happened again later at different offsets and about two to three times when measuring a section tray background. We did an intense antistatic cleaning and remeasure the tray - without success. After investigating former tech reports, it appears that intense antistatic cleaning and lowering down the measurement speed might help (see Tech Report of X369). After several antistatic cleaning and a lower speed setting (3 cm/s instead of 5 cm/s) with measurement conducted at 10 Hz (instead of 1 Hz), the flux jumps on the Y axis seem to disappear. These flux jumps are random and as mentioned in the tech report of X369, there is no explanation other than physics antennae effect.
• Several empty tray measurements were conducted and data files were sent to shore to give a status of the SRM to schedule a service call/visit of a technician during the tie-up in Cape Town (Expedition 397P).
• During a background measurement, home position of the tray was not recognized and the empty boat kept bumping into the home switch at the load position. The reason was that the home switch on mdrive board  was disconnected/loose (Figure 5). Checking the connection solved the issue.

Figure 5: Home switch on mdrive board which was disconnected

• As operations ended earlier (due to a failure of one of the drawworks electromagnet brakes), the SRM was shutdown on May 26, 2022 at 23:53 and warmed up during transit back to Cape Town to conduct a vacuum pump down. On May 28, 2022 when system was warmed up, hi cube pump was turn on at 10:38. Valve closed, the pressure at 1500 Hz was 9.2e-4 hPa. When the needle valve was cracked open for the first time at one third (1/3) of a turn, the pressure was 1.2.e-2 hPa (P_SIRM-initial) . The valve was closed and open again at one half of a turn, pressure was 9.2e-2 hPa. The needle valve was closed again to achieve low pressure. The turbo pump never lost speed (always 1500 Hz) during the procedure, as noticed during X391. Valve was then open half a turn and progressively open more. Pump down pressure was monitored (Figure 6). Slight increase in pressure is when the needle valve was open more. Maximum - valve believed to be fully open - was 3 turns on May 30. After 84 hours, the best pressure achieved was 3.2e-3 hPa. On May 31 at 23:55, the needle valve was closed and air in the hose was evacuated. The pump was turn off at 23:58. The SRM compressor was not turn on immediately so that we could check if the SRM was holding the vacuum. On June 2 at 7:54, the turbo pump was turn on. When the pump speed reached 1500 Hz, pressure was 8.4e-4 hPa. The needle valve was cracked at 10:00 for 1/4 of a turn, and then half a turn. Final pressure was 4.5e-3 hPa, similar to pressure achieved after pump down at the end of Expedition 391. At 10:20 on June 2, 2022 the compressor was turned on and cooling began.

Figure 6: SRM Vacuum Pump down at the end of the Expedition 390

• Comparison of SRM pressure values

Vacuum deteriorates with time. The SRM does not seem to hold the vacuum.

• After the vacuum pump down, a SRM field profile was performed (Figure 8, upper panel). The fluxgate (probe B) was zeroed before doing the profile. SQUIDS were then heated up to 10K and the field trapped. Field trapping was done on June 4, 2022, at berth in Cape Town (Figure 8, lower panel). When nulling the coils during the field trapping procedure, the elevator motion appeared to create important magnetic variations (Figure 9). Perhaps, leaving the elevator door open during the procedure might be necessary to prevent such issue.

Figure 8: Field trapping at the end of Expedition 390 in Cape Town

Figure 9: Variations during field trapping procedure due to elevator motion

Exp 391

• The noise level of the X axis on the SRM was higher than usual. This was not an issue during the expedition since the recovery was either extremely weak sediment or very strong basalt. The SRM was heated multiple time to until the SQUIDs were ~11k in order to release any trapped flux but this did not solve the issue. The electronics (control monitor, cable, and gold amplifier box) were swapped between the X axis and Y axis to see if the noise would follow the electronics or stay with the SQUIDs. After swapping the electronics, the noise was displayed on the Y axis monitor (which is now connected to the SRM X axis) so the noisy signal is related to the SQUID/SRM itself, not the external electronics. The oscilloscope was plugged in to monitor the SQUID signal. The amplitude of the X axis when it has the cleanest signal was ~.8V. The vendor manual says to adjust the I-bias to get the cleanest signal, not necessarily the largest amplitude but the amplitude should be between 1 and 5 volts. In consultation with Dave Schuler, he said the amplitude should certainly be greater than 1v. The largest amplitude I was able to achieve on the X axis was ~2v. As the amplitude increased on the X axis, the shape of the signal develops a distinct bump. The Y axis in contrast, has a very clean sinusoidal signal with an amplitude of 3v.

• The SQUID signal of the X axis when unlocked was very unstable and fluctuated with the pulses of the cryomech compressor. Dave Schuler said this appears to be flux leakage caused by the shield not remaining superconducting. He suggested warming the system to room temperature, using the hi-cube vacuum pump to pump the vacuum down, then cooling the system and seeing if the condition improves. A short video of the X Axis SQUID signal while unlocked is here.
  • The SRM compressor was shut down to warm the system on 2/1/22 at 19:00. While the system was warming, one thing that stood out is that the SQUID signal was not lost on the oscilloscope until ~11k for both the shield and the SQUIDS. Typically, I leave the compressor on and heat the system with the heaters. Using this method, the SQUID signal is lost at ~7.5k. I am not sure if this is important but it was interesting.
  • when the needle valve was first cracked open, the SRM pressure was 1.9e-3. This is the value recorded at the first sign of a pressure increase. The pump never lost speed and the pressure was still low so I continued to open the needle valve. At about a half turn open, the pressure was 3.5e-2. I opened the needle valve to 3/4 turn an the pressure read 5.9e-2. Again, the pump never lost any speed. I left the needle valve in that position for the rest of the pump down. The pump down curve as of ~50hrs of pumping is shown below. After ~50 hrs, the needle valve was opened to 2.5 turns and the pressure increased to 8.4e-3 hPa. After 2.5 turns, the pressure did not seem to increase anymore so 2.5 turns seems to be fully open. Note: counter clock wise turn opens the valve.

• The pump down procedure was terminated at ~73 hours since the pump down curve had flattened out. The compressor was turned on and cooling began at 16:00 hrs on 1/5/2022.

Exp 395E

• IMS does not do the correct calculations for working section halves. See software issues for more details.
• as of 6/3/2021, discrete measurements in the SRM are applying the background correction in the correct order. This issue has been resolved.
• as of 5/2/2021, discrete measurments in the SRM are still having the background applied incorrectly. See software issues for more details. Discrete samples should be run as Archive-top-away or working-bottom-away