2.1 ghz warm rf cavity for lerec binping xiao collider-accelerator department, bnl june 15, 2015...
TRANSCRIPT
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2.1 GHz Warm RF Cavity for LEReC
Binping XiaoCollider-Accelerator Department, BNL
June 15, 2015
LEReC Warm Cavity Review Meeting June 15, 2015
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Outline
Layout of the LEReC linac Description of 2.1 GHz warm RF system Summary
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LEReC layout
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LEReC layout
Two 3-cell 2.1GHz cavities
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Parameters
Phase I Phase II
Frequency 2.1107 GHz
Beam pipe ID [inch]
1.37
# of cells 3
Voltage [kV] 200 250
R/Q [Ohm] 480
G [Ohm] 170
Q0 14100
Pcav [kW] 5.92 9.25
RF power [kW]
10 12 or 15?
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2.1 GHz warm cavity: cell design
The 2.1 GHz bare cell: (a) perspective view; (b) front view; (c) side view.
(a) (b) (c)
Cavity end cell (a) perspective view (b) front view (c) side view.
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2.1 GHz warm cavity: coupler designCenter cell with the FPC and tuner: (left) perspective view; (right) side view.
WGHeight
Pickup coupler
(top) pickup coupler; (bottom) location of pickup coupler.
To provide 108 Qext, and 1W power at 200kV.
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2.1 GHz warm cavity: 3cellParameters for 3-cell cavity (length unit in mm).
phi [degree]
h Rd_e Rd_c WGHeight
50 4 52.578 50.8508 87
• Machining accuracy 0.001”.• 50 degree coupling slot is chosen for
the balance between coupling and shunt impedance for 3-cell.
• 4mm nose cone is chosen to maximize the shunt impedance.
• Radii of center cell and end cells are optimized for field flatness and resonance frequency at 0 tuner insertion.
• A gauge/arc detector port near RF window and a pickup port is designed (not shown here). A vacuum port near RF window is designed.
• JLab530 RF window (TiN coated) is placed far away from the cavity with an L-shaped waveguide to reduce the charge on the ceramic surface from beam.
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2.1 GHz warm cavity: EM field
Magnetic field
Electric field
For 200 kV:Peak electric field 3.6 MV/mPeak magnetic field 14.3 mT
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2.1 GHz warm cavity: tuner
Lt[mm] freq [GHz] Q0 Qext R/Q [ohm] -6 2.109027 14264 12771 488.76 0 2.110371 14309 13803 488.55 6 2.112746 14413 16600 483.57
12 2.114779 14533 20850 472.73
-6 -3 0 3 6 9 122.106
2.108
2.110
2.112
2.114
2.116
Lt [mm]
f [G
Hz]
-6 -3 0 3 6 9 12460465470475480485490495
Lt [mm]
R/Q
[O
hm
]
-6 -3 0 3 6 9 1214100
14200
14300
14400
14500
14600
Lt [mm]
Un
load
ed Q
-6 -3 0 3 6 9 1210000120001400016000180002000022000
Lt [mm]
Qex
t
Simulation results at different tuners’ penetrations: frequency, R/Q at β = 1, Q0 after considering 1.3 factor, and the FPC’s external Q.
RF performance for different tuner insertion
Accelerating component of the electric field on beam axis for 3-cell cavity at 1Joule stored energy, with tuner penetrations to be -6, 0, 6, and 12 mm.
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Summary There will be two warm RF systems in LEReC: 704 MHz and 2.1 GHz cavities.
For the 2.1 GHz warm RF system:
3-cell cylindrical cavity with nose cones and coupling slots is designed, and is optimized on shunt impedance.
FPC, vacuum port and gauge/arc detector port for FPC, tuner and Pickup coupler (Qext 108 to provide ~1W power at 200kV) are designed.
A vacuum pump will be attached to the cavity using a Tee on one of the beam pipe.
Cavity is fine tuned for field flatness.
Cavity performance at different tuners’ penetrations is evaluated.
The 2.1 GHz RF design is finalized.
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Thank you!