MICE Cavity Commissioning/Operation & Plans M.A Leonova MAP CM - - PowerPoint PPT Presentation

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MICE Cavity Commissioning/Operation & Plans M.A Leonova MAP CM Winter 2014

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MICE Cavity Commissioning/Operation & Plans

M.A Leonova MAP CM 6 December 2014

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MICE Cavity Commissioning/Operation & Plans

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MICE Cavity Commissioning/Operation & Plans

LabView system controls RF Fast Oscilloscopes LeCroy:

cavity pickup forward power reflected power1 reflected power 2

Tecktronics DPO

NaI crystal plastic scintillator cavity light cavity light

Tecktronics TDS

field emission probe Tuners left coupler Acoustic sensors field emission probe ACNET right coupler

• Vacuum (vessel and cavity)

light from left coupler

• Cavity temperature

light from right coupler

• Radiation monitors
• Frequency
• …

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MICE Cavity Commissioning/Operation & Plans

Normal pulse Modulator trip (~400) Breakdown event (32)

M.A Leonova MAP CM 6 December 2014

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MICE Cavity Commissioning/Operation & Plans

M.A Leonova MAP CM 6 December 2014

Aug/11 Aug/25 Sep/8 Sep/22 Oct/6 Oct/20 Nov/3 Nov/17

Inspect raw data of MICE RF test (Preliminary analysis)

• K. Yonehara & A. Tollestrup

APC, Fermilab

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Detector configuration for raw data

300 ft

▼ ▼

Lecroy wave runner 625 Zi PMT Plastic counter NaI crystal 1 m 1 m 201 MHz MICE RF Amplifier + Modulator Directional Coupler Tektronix DPO7000 Pickup Ref.2 Ref.2 Forward Wave Guide

time res. = 0.2 ns ~25 pts per RF cycle time res. = 5 ns ~1 pt per RF cycle

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Analyze four different events

• Normal event
• Typical breakdown event
• Unusual breakdown event
• Modular trip

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Normal event

2000 4000 6000 8000 10000 12000 0.0 0.5 1.0 1.5 2.0 2.5 3.0

40 ns/bin Arb. 0.00030 0.00035 0.00040 0.00045 0.1 0.2 0.5

Emax =13.6 MV/m  = 67.3 s Q = 85,100

time [s] Pickup signal [V] Frequency [Hz]

Oct 31, 2014 16:06:37

12,000 bin = 480 s

Pickup Forward

• Ref. 1
• Ref. 2

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2000 4000 6000 8000 10000 12000 1 2 3 4

Typical breakdown event

40 ns/bin Arb.

Emax = 11.9 MV/m  = 0.65 s Q = 822

time [s] Pickup signal [V] Frequency [Hz]

Nov 14, 2014 1:54:03

12,000 bin = 480 s

Pickup Forward

• Ref. 1
• Ref. 2

Frequency shift!

NaI crystal Plastic counter Light 1 Light 2 11

2000 4000 6000 8000 10000 12000 1 2 3 4

Un‐usual breakdown event

40 ns/bin Arb.

Emax = 13.6 MV/m  = 0.65 s Q = 822

time [s] Pickup signal [V] Frequency [Hz]

Oct 28, 2014 19:30:30

12,000 bin = 480 s

Pickup Forward

• Ref. 1
• Ref. 2

Frequency shift!

NaI crystal Plastic counter Light 1 Light 2 12

Possible mechanism of frequency shift

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1: C L  L Additional Conductance + Inductance due to a current flow

    1 2 L L

Additional inductance induces a frequency shift In the electric breakdown (BD) → Although, we do not know the source of electrons, yet… → Electrons could be accelerated by the RF field and become a current → The current reduces the inductance of cavity → Consequently, it increases the resonant frequency BD results in the MICE RF indirectly suggest the current model

L  0l 2 ln 2l a       3 4      

l: Cavity gap a: Radial size of the current where Normal resonator circuit

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Possible modular trip event

Nov 7, 2014 17:23:51

Although we see a big reflection in RF signal (see a green line in the left plot) there is no light (see in the right plot) & the RF decay time is very long as the same as a normal RF signal → This is classified as “Modular trip” or fake breakdown signal

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MICE Cavity Commissioning/Operation & Plans

M.A Leonova MAP CM 6 December 2014

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MICE Cavity Commissioning/Operation & Plans

Plans:

• Cavity surface inspection
• Install Be windows
• Preparation for operation in magnetic field

 Modifications to the vacuum system  Move cavity closer to the magnet  Re-train the magnet

• Run

 W/O magnetic field  Tuner test  With magnetic field

M.A Leonova MAP CM 6 December 2014