All Seasons Cavity Analysis Waveform analysis Spark - PowerPoint PPT Presentation

All Seasons Cavity Analysis Waveform analysis Spark characterization A. Kochemirovskiy Uchicago/Fermilab 4/8/2015 1

Motivation • IPAC paper submission deadline is: Wednesday, 29 April, 2015 at midnight in Richmond (GMT-5) “Breakdown characterization in 805MHz pillbox - like cavity in strong magnetic fields” • Physical questions we want answers to: – What does typical spark look like? – How does it depend on pulse parameters? • Run history questions I want answers to: – Magnetic field – Any info there is 4/8/2015 2

Data MTA3 server Scope’s .bin and .csv files Labview’s Log files Capture every 20 mins + “sparks” (not synced) 4/8/2015 3

Relevant formula CSV = SCV = CVS ≠ ASC CSV - Comma Separated Values SCV - Space Construction Vehicle ( StarCraft 1) CVS - Consumer Value Stores ( Pharmacy ) 4/8/2015 4

Waveforms collected Tektronix - “slow” scope ( ~ 1ns sampling rate) Lecroy - fastest scope ( 0.1ns sampling rate) 4/8/2015 5

Data structure Log Files Lecroy CSV Lecroy PNG B field 28-Feb 3T? : 3T? 13-Mar 3T? Comments : 3T? 21-Mar 3T? • : 3T? ~ 2000 CSV files, ~ 25Gb 23-Mar 3T -> 0T • Python – nice programming interface, : 0T : although weaker math libraries 0T 5-Apr 1T • 6-Apr 2T Looked at the pickup signal data only 7-Apr 3T (Lecroy Channel 1) 8-Apr 3T : ? 22-Oct ? 4/8/2015 6

Calibration 2013-03-02 10:12:55 Calibration point: 1.02 V pickup on LabView = 0.74 V on scope (with 6dB att) = 5.5 MV/m 2013-03-02 11:38:34 Calibration point: 1.61 V pickup on LabView = 1.06 V on scope (with 6dB att) = 7.8 MV/m 24 y = 7.4006x - 0.0094 22 R² = 0.9998 20 Gradient, MV/m Gradient [ MV/m] = 7.4* Max_amplitude 18 16 14 12 10 1.5 2 2.5 3 3.5 Lecroy Max Pickup Amplitude, V 4/8/2015 7

Run history Based on Labview’s Probe Peak data Based on Lecroy waveforms 26 MV/m Gradient [MV/m] = 3.7* Probe_Peak ( Labview Log) Gradient [ MV/m] = 7.4* Max_amplitude_scope (CSV) 4/8/2015 8

Pickup Signal 4/8/2015 9

Envelope 4/8/2015 10

Envelope of envelope 4/8/2015 11

Normal event Max_amplitude 4/8/2015 12

Normal event τ – Decay constant (decay time constant) T – decay time 4/8/2015 13

Typical spark 4/8/2015 14

Typical spark 4/8/2015 15

Decay times March 11 th -20 th March 20 th – 23 rd March 23 rd – 27 th March 27 th – April 10th Cutting 4/8/2015 16

Decay constants vs gradient Normal events March 13 th – Apr 5 th Apr 5 th – 6 th Apr 6 th – 7 th Apr 7 th – 10 th Sparks 4/8/2015 17

Decay constants vs gradient – normal events March 13 th – Apr 5 th Apr 5 th – 6 th Apr 6 th – 7 th Apr 7 th – 10 th 4/8/2015 18

Some spark statistics Total number of sparks - 89 4/8/2015 19

Spark current estimation 𝐷𝑊 2 Basic model: all stored energy 2 goes into the spark current: 𝑢 𝑅 = 𝑅 0 exp (- τ ) 𝑅 0 𝑢 I = − τ exp (- τ ) 4/8/2015 20

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Backup 4/8/2015 22

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Backup 2013-04-05 17:59:00.683, 2461790, Comment, Now at 1T. 2013-04-06 11:09:42.426, 2522471, Comment, Now at 2T 2013-04-07 11:01:42.137, 2606858, Comment, Now at 3T 2013-04-08 20:13:57.921, 2724031, Comment, Start ramping down B field. 2013-03-02 09:53:45.582, Comment, Running at 3T, good vacuum IG1=7E-9, current pickup amplitude 476mV (3.5 MV/m) 2013-03-02 10:12:55 Calibration point: 1.02 V pickup on LabView = 0.74 V on scope (with 6dB att) = 5.5 MV/m 2013-03-02 11:29:54.079, Comment, Calibration point: 1.4 V pickup on LabView = 0.95 V on scope (with 6dB att) = 7 MV/m 2013-03-02 11:38:34 Calibration point: 1.61 V pickup on LabView = 1.06 V on scope (with 6dB att) = 7.8 MV/m # 2013-03-23 16:18:58.191, 1354823, Comment, After ramping down the magenetic field, we obaserve abrupt change in the tempearute reading (19 --> 7 -->16, etc) 4/8/2015 26