Ground Plane Data Analysis Heng-Ye Liao, Alan Hahn, Cheng-Ju Lin, - - PowerPoint PPT Presentation

Ground Plane Data Analysis

Heng-Ye Liao, Alan Hahn, Cheng-Ju Lin, Sarah Lockwitz 11/08/2017

Setup of Ground Planes Instrumentation

TOP-EAST (TE)

TOP-WEST (TW)

TOP-SOUTH (TS) TOP-NORTH (TN) VERTICAL-UP (VU) VERTICAL-DOWN (VD) BEAM PLUG PLATE (BP) Bottom (BOT)

Ground Planes instrumentation DAQ

39 V MOV 1 MΩ 4.7 MΩ 10 V TVS Diodes R=5.7 kΩ

Voltage divider [1] [2]

Voltage limit of the ground plane DAQ: ±10 V [0]Circuit inside cryo [1]Circuit outside cryo to limit the input voltage to ±10 V [2]Circuit to reduce the high input impedance

Simplified Electrical Circuit of Ground Planes Instrumentation

[0] (Pomona box)

Ground Planes instrumentation DAQ

39 V MOV 1 MΩ 4.7 MΩ 10 V TVS Diodes R=5.7 kΩ Voltage divider

[1] [2]

Readouts of Ground Planes

[0]

To ground D-sub connector NI DAQ

Pomona boxes

Inside cryostat Outside cryostat

Signal readout

Ground Plane Signals

• Ground plane (GP) signal: Currents across 1 MΩ resistor
• Calibration of signal in the NI DAQ:

→ 1 mV is equivalent to 1 uA, i.e. 1 V signal in a ground plane

• DAQ sampling rate: 1 kHz
• Signal shape:

A signal in one ground plane is negative. Other GPs are capacitively coupled to the field cage (voltage drops on the field cage)

• GP Signal Detection: Any GP trace above 5 mV or below -5 mV
• Event Display: Pre-trigger: 10 msec / Post-trigger: 400 msec

Time since start of this data set [sec]

Saturation because of 39 V MOVs Responses of other ground planes

M e a s u r e d V

• l

t a g e i n t h e N I D A Q [ m V ]

A signal on the vertical-down ground plane

Ground Plane Signals: Multi-Hit Signals

A Two-Hit Example: Vertical-Up + Beam Plug Plate An example of a multi-hit event

Ground Plane Signal: “No-Visible-Hit”

• No Visible Hit (NVH) signal:

Ground planes response to the activities of the field cage

Ground Plane Signal: NVH Cont’d

+ A time delay signal ~ 4 sec later

Toroid always triggers for this type of event. → It indicts that this type of GP event is associated with fast discharge

• NVH signal with a delay signal (NVHD)

Ground Plane Signal: NVH Cont’d

• Few words about the NVH signals

→ No viable hit doesn’t mean there is no hit. Simply because the sampling rate of the NI DAQ is not fast enough. Fast discharge A typical toroid signal for a fast discharge (Screen grab taken by Alan) 1 µs

Ground Plane Data Taking

• Before 10/03, we do not have the vertical-up ground plane

data, due to the cable connection problem.

Vertical-up ground plane was not connected before 10/03

Ground Plane Data Taking

• Before 10/03, we do not have the vertical-up ground plane

data, due to the cable connection problem.

• To have better time resolutions on the pickoff signals, we

implemented the east, the west, and the beam plug pickoff to the NI DAQ after 10/12.

• We lost data due to the hard drive crash event → Some info

can still be extracted from the 35ton e-log

• Data analysis on the ‘good’ data sets

(with GP signals+Heinzinger signals)

GP Activities (Steady HV) - Time Distribution

Events associated with Toroid signals (fast discharges) Events associated with Toroid signals (fast discharges)

Ramping up from 135 kV to 145 kV Ramping up from 135 kV to 145 kV

Events with no Toroid signals Events with no Toroid signals

We lost the data in this period. Lost data due to the hard drive crash. Lost the communication with the Heinzinger. After VU was fixed Transition phase (Flushing N2 gas to the beam plug)

Summary of Ground Plane Activities (Steady HV)

Summary of GP Activities (HV Discharges)

Event #

Time Stamp of Ground Plane Trigger Set HV [kV] Power Supply Tripping Time Time Stamp

• f Toroid

1

09/23/17-06:06:35.436 PM BP 130 09/23/17 06:06:37.752 PM 09/23/17-06:06:37.--- PM

2

10/01/17-07:03:43.253 AM BP 145 10/01/17 07:03:43.297 AM 10/01/17-07:03:43.--- AM

3

10/02/17-09:50:00.455 AM NVH 120 10/02/17 09:50:01.159 AM

• 4

10/13/17-05:36:43.181 PM NVH 130 10/13/17 05:36:43.660 PM 10/13/17-05:36:43.461 PM

5

10/19/17-09:11:34.326 AM NVH 115 10/19/17 09:11:34.801 AM 10/19/17-09:11:34.625 AM

6

10/19/17-07:23:13.355 PM NVH 120 10/19/17 07:23:13.724 PM 10/19/17-07:23:13.510 AM

• Toroid saw HV trips → Fast discharges
• 6 GP events are associated with HV trips

4 are NVH and 2 are BP (+VU)

• Reminder: Before we fixed the VU ground plane (10/03), there were no VU signals.

From our observation, BP always comes with VU.

Summary & Outlook

• Ground Planes are sensitive to activities associated with the

field cage: Ramping up, HV trips, slow discharges, and fast discharges → Good tools for HV Monitoring

• For the Phase 2 HV test → No obvious single weak spot
• Activities near the top-west and the beam plug-plate area
• Working in progress:
• Studying in the time-correlated signals of the

east/west/beam Plug pick-offs

• Trying to study more for the ‘fast-discharge’ GP events from

their traces

Backup

GP Activities after HV Trips

Event # GP Time Stamp Trigger Power Supply Tripping Time Time Stamp of Toroid 1 09/15/17-11:37:10:533 AM MH 09/15/17 11:36:52.793 AM

• 2

09/17/17-07:33:53:106 PM MH 09/17/17 07:33:17.804 PM

• 3

09/17/17-07:34:39:677 PM MH 09/17/17 07:33:17.804 PM

• 4

09/18/17-05:10:49:877 PM NVH 09/18/17 05:10:48.868 PM

• 5

09/21/17-02:53:43:450 AM BP 09/21/17 02:53:42.309 AM 2017_09_21-02_53_42.--- 6 10/01/17-07:04:14:039 AM MH 10/01/17 07:03:43.297 AM

• 7

10/02/17-09:33:03:161 PM NVH 10/02/17 09:33:02.796 PM 2017_10_02-21_33_02.--- 8 10/03/17-03:59:27:376 PM BP 10/03/17 03:59:27.235 PM 2017_10_03-15_59_27.--- 9 10/13/17-05:38:51:808 PM MH 10/13/17 05:36:43.660 PM 10 10/19/17-09:14:51:269 AM VD 10/19/17 09:11:34.801 AM 11 10/19/17-09:16:45:819 AM MH 10/19/17 09:11:34.801 AM 12 10/19/17-07:23:37:475 PM VD 10/19/17 07:23:13.724 PM

• 50% of the GP events are MVHs; 3 associated with fast discharges

GP Activities during Ramping Up

Heinzinger HV [kV] BOT VD NVH

• GP Entries :
• BOT: 26
• VD: 1
• NVH: 12

Extracting Info from Pick-offs

Instrumentation of Pick-Offs

GP DAQ

10 V Zener Diodes

Pick-off

Pomona Box

[1] Not shorting out the Keithley signals → 3kV capacitor (OIM Z5U) [2] Protection on ground plane DAQ → 10 V Zener Diodes (1n758) [1] [2] Keithley Blocking capacitor B.P. PO to GP DAQ To GP DAQ