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

MICE Cavity Commissioning/Operation & Plans M.A Leonova MAP CM Winter 2014 1

MICE Cavity Commissioning/Operation & Plans M.A Leonova MAP CM 6 December 2014 2

MICE Cavity Commissioning/Operation & Plans … 3

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 - … 4

MICE Cavity Commissioning/Operation & Plans Normal pulse Modulator trip (~400) Breakdown event (32) M.A Leonova MAP CM 6 December 2014 5

MICE Cavity Commissioning/Operation & Plans Aug/11 Aug/25 Sep/8 Sep/22 Oct/6 Oct/20 Nov/3 Nov/17 M.A Leonova MAP CM 6 December 2014 6

7 Inspect raw data of MICE RF test (Preliminary analysis) K. Yonehara & A. Tollestrup APC, Fermilab

8 Detector configuration for raw data Lecroy wave runner 625 Zi Tektronix DPO7000 time res. = 0.2 ns ~25 pts per RF cycle Ref.2 time res. = 5 ns Forward Wave Guide 300 ft ~1 pt per RF cycle ▼ PMT Directional Coupler ▼ Amplifier + Modulator Pickup 1 m Plastic counter 1 m Ref.2 201 MHz NaI crystal MICE RF

9 Analyze four different events • Normal event • Typical breakdown event • Unusual breakdown event • Modular trip

10 Normal event Pickup signal [V] Arb. Oct 31, 2014 16:06:37 3.0 0.5 Pickup 2.5 Forward E max =13.6 MV/m 2.0  = 67.3  s 1.5 Ref. 1 Q = 85,100 0.2 1.0 0.5 Ref. 2 0.1 0.0 0 2000 4000 6000 8000 10000 12000 0.00030 0.00035 0.00040 0.00045 40 ns/bin 12,000 bin = 480  s Frequency [Hz] time [s]

11 Typical breakdown event Pickup signal [V] Arb. Nov 14, 2014 1:54:03 4 Forward E max = 11.9 MV/m Pickup 3  = 0.65  s Ref. 1 Q = 822 2 Ref. 2 1 12,000 bin = 480  s 0 0 2000 4000 6000 8000 10000 12000 40 ns/bin NaI crystal Frequency [Hz] Plastic counter Frequency shift! Light 1 Light 2 time [s]

12 Un ‐ usual breakdown event Pickup signal [V] Arb. Oct 28, 2014 19:30:30 4 Pickup E max = 13.6 MV/m 3 Ref. 1  = 0.65  s Forward 2 Ref. 2 Q = 822 1 12,000 bin = 480  s 0 0 2000 4000 6000 8000 10000 12000 40 ns/bin NaI crystal Frequency [Hz] Plastic counter Frequency shift! Light 1 Light 2 time [s]

13 Possible mechanism of frequency shift 1:   Additional L C Conductance + Inductance S  L due to a current flow Normal resonator circuit Additional inductance induces a frequency shift     L    L   0 l    1 ln 2 l  3 l : Cavity gap  where     2    a : Radial size of the current 2 L a 4 In the electric breakdown (BD) → Although, we do not know the source of electrons, yet… → Electrons could be accelerated by the RF fi eld 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

14 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 classi fi ed as “Modular trip” or fake breakdown signal

MICE Cavity Commissioning/Operation & Plans M.A Leonova MAP CM 6 December 2014 15

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 16