Hall D Solenoid: Voltage Spikes in Coil 2


Lats updated: 20 Jan 2017 by gen@jlab.org

Voltage spikes have been observed in coil 2 at fast changes of the field. Such spikes often happen at the starts of the fast dumps. Sometimes they happen at the regular current ramping. Fast (a few ms), 10-50V spikes happen in the subcoil 2D (the one supported by the added buttresses). In December 2016 slower (hundreds of ms) and smaller spikes tripped the magnet at ramping up.

Trips during ramping up in December 2016

On Dec 13-14 the magnet tripped 3 times at the regular ramping rates. The Quench Detector was triggered by voltage excursions in Coil 2.

  1. 2016/12/13 17:41:26 Trip at 740A, 0.2A/s, See LOG 3446267
  2. 2016/12/13 19:37:15 Trip at 505A, 0.2A/s, See LOG 3446295
  3. 2016/12/14 09:31:50 Trip at 1150A, 0.06A/s, See LOG 3446544 Very similar to the trip on 2016/12/13 17:41:26, see the plots here and here , but without a spike at the dump. The voltage excursion on 2D reached +0.3V and went down.

Other trips and spikes in Coil #2


  1. 2016/03/28 09:03:30 Trip at 510A, 0.2A/s, See LOG 3392805
  2. 2017/02/07 13:58:10 Trip at 1350A, 0A/s, See LOG 3456545 caused by accidental pushing the crash button in the refrigerator building. During the initial phase of the dump (at -10V at the magnet) the typical ≈ -30V spike happened on the VTT7. The spike had an internal structure of 3 ≈1ms sharp spikes. After the dump resistor was engaged, several sharp spikes followed, producing also signals in the accelerometer. There are various plots in: here, here, here,