[Dsg-hallb_magnets] Solenoid load cells during ramp downs and dumps

Amrit Yegneswaran yeg at jlab.org
Mon Oct 22 18:12:30 EDT 2018 

excellent tyler 



From: "Tyler Lemon" <tlemon at jlab.org> 
To: "Dave Kashy" <kashy at jlab.org>, "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org>, "Ruben Fair" <rfair at jlab.org> 
Sent: Monday, October 22, 2018 3:05:20 PM 
Subject: Re: [Dsg-hallb_magnets] Solenoid load cells during ramp downs and dumps 

Hello, 

To "zoom in" on the latest experimental run period, I also generated the same plots as in my previous email but from August 1, 2018 to October 18, 2018. To try to get more detail, data was retried at 10-minute intervals during that time period. 

The coloring on the plots are the same as in my previous email. 

Best regards, 
Tyler 


From: "Tyler Lemon" <tlemon at jlab.org> 
To: "Dave Kashy" <kashy at jlab.org>, "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org>, "Ruben Fair" <rfair at jlab.org> 
Sent: Monday, October 22, 2018 2:59:31 PM 
Subject: Re: [Dsg-hallb_magnets] Solenoid load cells during ramp downs and dumps 

Hello, 

In the attached PDF, there are plots of all 16 of the Solenoid's load cells from September 12, 2018 at noon (day close to magnet's first fast dump) to October 13, 2018 at noon (day data was retrieved from Mya). Data was retrieved for the load cell at the top of the hour for every hour during that interval. 

In the PDF, each load cell is plotted twice. The data displayed in the two plots are identical, but the two plots' coloring differ. In the top plot, blue indicates times when the Solenoid was powered and green indicates times when the Solenoid was off. In the bottom plot, blue indicates times when the Torus was powered on and green indicates times when the Torus was off. 

Some of the plots look to have places where there are gaps between colors, RS86101US_BR_B (page 1) around the start of March 2018 for example. These gaps are a side effect of the masking used plot different colors depending on the power status of the magnets. 

On all plots there, there are also 19 vertical, red lines corresponding to the 19 fast dumps the Solenoid has suffered. 

>From these plots, we have noticed: 


    1. There is indeed a difference in load cell values when the Torus is on versus when the Torus is off, as Dave mentioned there would be. 
        * When Torus is on, the LCs read ~400 lbsf greater than when Torus is off. 
        * One of best examples of this is for RS86101US_BR_B (page 1) from at the beginning of September 2018 (Solenoid on, Torus off) and at the end of September 2018 (Solenoid on, Torus on). 
    2. Load cell trends: 
        * Since September 2017, there was a general decreasing trend in LC readings for all LCs up until the middle of Summer 2018. 
        * Since August 2018, there has been a slight increasing trend in the radial LCs and a slight decreasing trend in the axial LCs. 
        * Over the summer in 2018, there was also a large change in LC readings, but this is most likely due to the magnet being parked at 80 K for an extended period of time. 
            * Are any of these significant increases/decreases? 
    3. There appears to be three LCs that have read zero for extended periods of time. 
        * RS86103DS_BR_T (page 3) has read zero since the end of October 2017 
        * ZS86105US_BL_T (page 13) read zero from mid-December 2017 to start of April 2018. Since April 2018, it has read very low values. 
        * ZS86108US_BS_B (page 16) has read zero since mid-June 2018. 
            * Would these zero readings be from instrumentation failures? 
            * Is is important or necessary to fix these? 

>From what I can see, there does not appear to be any significant affect of the fast dumps on the LC values. It seems that long term cryogenic warm-ups (Summer 2018 park at 80 K) and magnet power status (on vs off; full current vs half current) affect the load cell readings the most. 

Best regards, 
Tyler 


From: "Dave Kashy" <kashy at jlab.org> 
To: "Tyler Lemon" <tlemon at jlab.org> 
Cc: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org>, "Ruben Fair" <rfair at jlab.org> 
Sent: Wednesday, October 10, 2018 5:43:57 PM 
Subject: Re: [Dsg-hallb_magnets] Solenoid load cells during ramp downs and dumps 

Hi Tyler, 

Besides looking at the forces and Solenoid current. Please include Torus current as it strongly effects the load of the supports. 
Small changes in settled out forces will not be surprising, loads can shift from one support to another... 

Dave 

----- Original Message ----- 
From: "Ruben Fair" <rfair at jlab.org> 
To: "Tyler Lemon" <tlemon at jlab.org> 
Cc: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org> 
Sent: Wednesday, October 10, 2018 3:17:02 PM 
Subject: Re: [Dsg-hallb_magnets] Solenoid load cells during ramp downs and dumps 

Good idea Tyler - thank you 

Ruben 

On Oct 10, 2018, at 3:11 PM, Tyler Lemon < tlemon at jlab.org > wrote: 




Hello, 

Because the Solenoid has had several fast dumps, DSG is starting to look at whether the load cell forces have changed for the Solenoid as a result of the dumps. 

Attached is an example of what we are comparing. 

"Solenoid LC during ramp down.PNG" shows the values for one of the Solenoid's radial load cells during the purposeful ramp to zero yesterday morning. When Solenoid was at full field, the LC read 9077 lbs. During the ramp down, the LC dropped to 8748 lbs before increasing slightly to 8768 lbs. All of this is over the course of about 1 hour for an approximate overall change of -5 lbs/min. 

"Solenoid LC during fast dump.PNG" shows the values for the same load cell during last night's fast dump. The LC goes from 9074 lbs to 8699 lbs before increasing slightly to 8730 lbs. All of this is over the course of about 30 seconds for an approximate overall change of -688 lbs/min. 

We plan to compare values for all load cells in a similar way to see whether forces have changed as a result of the fast dumps. 

Best regards, 
Tyler 







<Solenoid LC during ramp down.PNG> 



<Solenoid LC during fast dump.PNG> 



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