Dielectric Strength Test Status B. Freemire IIT HPRF/Vacuum - - PowerPoint PPT Presentation

Dielectric Strength Test Status

• B. Freemire

IIT HPRF/Vacuum Meeting September 9, 2015

9/9/15

• B. Freemire - HPRF/Vacuum Meeting

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Dielectric Strength Test Goal

• Determine the dielectric strength of each of the four purity (96, 98.5, 99.5 & 99.8%)

samples of alumina

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Ramp up E-field slowly

• May require some conditioning, as per past experience

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Induce breakdown in the cavity and then back off in E-field until sparking stops

• Use nitrogen to ease the safety requirements and compare measurements

with past results

• Run at Station 2 to minimize conflict with MICE or MC programs

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Repeat at different gas pressures

9/9/15

• B. Freemire - HPRF/Vacuum Meeting

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Operational Pressure Range

• Using existing spacers:

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Pressure range for donuts:

• 99.5%: 31.2 – 87.4 atm
• 98.5%: 48.4 – 98 atm (safety)
• 96%: 62.6 – 98 atm (safety)

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Pressure points:

• 99.8%: 35, 50, 75, 85
• 99.5%: 35, 50, 75, 85
• 98.5%: 50, 75, 85, 98
• *96%: 65, 75, 85, 98

9/9/15

• B. Freemire - HPRF/Vacuum Meeting

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Run Plan

1) Pressurize the cavity with 50 atm N2 2) Tune klystron at low power 3) Ramp up E-field in 1.0 MV/m steps 4) Wait 5-8 minutes at each step 1) Record 2 RF pulses 2) If no sparks observed, move on 3) If few sparks observed, wait longer 4) If many sparks observed, decrease E-field 5) ~2 hours to reach 14 MV/m 5) Once E-field limit reached, collect 5,000 pulses 1) Record every 500 pulses 2) ~2.75 hours at 0.5 Hz 6) Repeat at three other pressures, then return to 50 atm

9/9/15

• B. Freemire - HPRF/Vacuum Meeting

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Timeframe

• I would like to complete 2 gas pressures per day
• 5 pressures / 2 per day = 2.5 days required per donut
• 2.5 days per donut x 4 donuts = 10 days of data taking
• 1 day setup per donut x 3 donuts = 3 days setup
• 10 days data + 3 days setup = 13 days
• Wait time and # of RF pulses may be affected by heating of cavity

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Four thermocouples installed on HPRF cavity

• Pressure window, coupler waveguide, end plate, cavity equator

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Monitor pressure gauges during running

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ACNET parameters:

• Pressure – E:C8GLP1 & E:C8GLP2
• Temperature – E:C2TC45-48

9/9/15

• B. Freemire - HPRF/Vacuum Meeting

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Accomplished

• Pressure test passed as of September 1st

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Awaiting safety paperwork to be processed

• Operational pressure relief valve installed
• Full bottle of N2 ready

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Purchase order for dry air completed

• RF calibration complete

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1 MV/m on axis = 1.75 MV/m on donut = 4.052 kW

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Magnetic probe: -32.0 dB, electric probe: -34.4 dB

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Q0 = 8,875

• Cavity connected to waveguide and waveguide pressurized
• Thermocouples reinstalled
• (Most) Signal cables connected

9/9/15

• B. Freemire - HPRF/Vacuum Meeting

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To Be Done

• Check for leaks in new pressure relief valve
• Connect optical fibers to cavity and PMT box
• Connect signal cables to PMTs
• Power PMTs
• RF switch moved to position for Station 2
• Verify DAQ configuration
• Order new gaskets

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Awaiting new drawings from Terry when he returns on Monday

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Thicker radial diamond structure