[Dsg-hallb_magnets] Question regarding current fastDAQ data from Solenoid fast dump on Sept 13, 2017

[Amrit Yegneswaran]

i don't understand "an artifact of the local measurement". 

the data is acquired at 10KHz, the first peak is ~20,000 V, then ~59,000 V, ~69,000 V, ~69,000 V, ~69,000V, ~250,000 V. 
it appears as if there is current scaling (factor of 10,000 )?? 
perhaps there is a scale factor somewhere on the instrument. 



From: "George Biallas" <biallas at jlab.org> 
To: "Tyler Lemon" <tlemon at jlab.org> 
Cc: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org> 
Sent: Thursday, September 14, 2017 10:02:28 AM 
Subject: Re: [Dsg-hallb_magnets] Question regarding current fastDAQ data from Solenoid fast dump on Sept 13, 2017 

Folks, 
I think these spikes are an artifact of the local measurement and are not really going through the magnet. 

As I read the graph, each division is 0.002 s. 

The linear portion of the largest spike takes place over ~0.0004 s. 

The current rise during that time is ~22 A. 

That calculates to a dI/dt of 55000 A/s. 

The voltage to drive that spike through the magnet inductor of 5.89 H is L*dI/dt. 

I calculate 323,950 V !!! 

I don't think that voltage is available. 




From: "Tyler Lemon" <tlemon at jlab.org> 
To: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org> 
Sent: Thursday, September 14, 2017 9:21:44 AM 
Subject: [Dsg-hallb_magnets] Question regarding current fastDAQ data from Solenoid fast dump on Sept 13, 2017 




BQ_BEGIN

Hello, 

This morning, Pete Bonneau and I were looking at the fastDAQ data Brian and Pablo sent yesterday of the ~1 second where the fast dump happened in the Solenoid. 

We noticed that the current jumps ~15A and then decays several times at the very start of the ramp down (plot attached). 

We think that these oscillations are caused by the dump switch flipping. Is this the cause of these oscillations? If not, what is causing the current to jump like that at the start of the fast dump? 

Please let us know. 

Best regards, 
Tyler 

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BQ_END


-- 
George 

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