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Re: [Sphenix-magnet-l] Reached 5% over the operating current, slowly discharged and then fast discharged all peacefully
- From: EdwardOBrien <eobrien AT bnl.gov>
- To: sphenix-magnet-l AT lists.bnl.gov
- Subject: Re: [Sphenix-magnet-l] Reached 5% over the operating current, slowly discharged and then fast discharged all peacefully
- Date: Tue, 13 Feb 2018 20:32:06 -0500
Hi Kin, You and your whole team from C-AD and SMD did a really great job. Thanks to all the Physics people that contributed too. It was an outstanding outcome due to to a large group of dedicated and hardworking experts. Ed On 2/13/2018 4:57 PM, Kin Yip wrote:
Hi,As Achim has disclosed earlier, we reached ~4830 A this afternoon and due to the availability of Liquid He, we stayed for ~40 minutes. They actually watched that the gas-cooled lead voltage stabilized, stopping to go up, before they started the slow discharge. Carl and the Cryo group have been discussing about optimizing the lead flow rate from 0.27 g/s to 0.33 g/s as the max. (at 5000 A). Brian van Kuik told me that the max. they reached was ~0.31 g/s. This morning, when we tried to ramped to 2 A/s to 4000 A, the pet page etc. suddenly all disappeared in front of us (in 912 or my office or anywhere). The C-AD control file system crashed ! When did this happen last time ?! One felt like everything was against us, at that point. At that time, the power supply/magnet was ramping up and after the file system crash, we could only observe from Zeynep's quench-detection system (PXIe) screen or Pablo's power supply touch-screen :-) Around 2500 A, Carl's phase-locked-loop (PLL) was lost which causing Zeynep's PXIe to issue a fast-discharge (for quench protection) --- which had not happened since we started testing in 912. Maybe, the loss of PLL was due to the control system failure or maybe not ??! ( Depending on who you ask ... ) We couldn't ramp (even John Morris discouraged from there doing so) as there was no Logging (slow logging or fast logging) to monitor etc. Luckily, shortly before 1 pm, the control system was back to operation. After testing a bit at 100 A, we started ramping at 2 A/s to 4000 A and then 2 A/s in 200 A step (or 230 A for the last step). As mentioned, we reached ~4830 A and stayed there for ~40 minutes and did the slow-discharge, to avoid the Liquid Helium tank being empty. The slow-discharge is slow and the calculator that I created said that it'd take ~6102 seconds to go from 4830 A to 0. It's slower at the end :-) Just like BaBar, people don't want to wait for it to slowly go to 0. So, at below 1000 A (or ~966 A or so), we did a fast discharge. This saved waiting for another almost 40 minutes. I attached the 2018-2-13.gif for today's current and Magnetic field. Our Opera calculation/simulation assuming 1010 steel, for this Return Flux (Steel Box), predicts a magnetic field of 1.37 T at 4596 A. At ~4830 A, we got ~1.34 T whereas at 4600 A, we got ~1.275 T. Almost 7% lower than expectation. I guess the probe was probably not exactly at the center and the 40+ years old steel is far from what we expected (rusty too). A surveyer today was also there trying to measure any sidewards expansion and I heard that he got only 0.002 inch (within their error/uncertainty) between 0 and 4000 A. Jon Hock came to my office to make me plot his linear pots and there we also saw the maximum of 0.002 inches between 0 and 4830 A. All smaller than the engineers have been worried about. Kin PS: I've read Monday Memo and heard about the "new" Day-to-Day Appreciation and Recognition more than once. I'm trying to fill out the "Group Food Celebration Recognition Form", https://sbms.bnl.gov/SBMSearch/subjarea/55/5509e011.pdf , to see whether it'd work :-) On 02/13/2018 02:57 PM, Franz, Achim
wrote:
Great news
Magnet is at 4830A = 105%
operating point
Sent from my iPhone
Achim Franz
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[Sphenix-magnet-l] Magnet at 4830A,
Franz, Achim, 02/13/2018
- [Sphenix-magnet-l] FW: Magnet at 4830A, Sondheim, Walter E, 02/13/2018
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[Sphenix-magnet-l] Reached 5% over the operating current, slowly discharged and then fast discharged all peacefully,
Kin Yip, 02/13/2018
- Re: [Sphenix-magnet-l] Reached 5% over the operating current, slowly discharged and then fast discharged all peacefully, John Haggerty, 02/13/2018
- Re: [Sphenix-magnet-l] Reached 5% over the operating current, slowly discharged and then fast discharged all peacefully, EdwardOBrien, 02/13/2018
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