RADIO FREQUENCY QUADRUPOLE
Radio Frequency Quadrupole Structure
Preliminary design studies have been conducted for the 350 MHz Radio Frequency Quadrupole for the thermal & structural stability of structure. The activities relating to the development of RFQ are :
Thermal Design of RFQ Structure
The 3 MeV 352 MHz RFQ structure has been designed for SNS/ High duty application. Geometric parameters of the RFQ are being optimized by RF-Thermal-Structural coupled analysis.
The RFQ has been designed as integrated four vane cavity type structure of octagonal shape and will be made of OFHC copper. Based on the beam dynamics and RF design, the RFQ will be around 3.6 m long cavity having three segments of approximately 1.2 meter length each.
The RFQ structure has been studied for temperature distribution and thermal deformations. The Thermal-Structural-Electromagnetic coupled analysis has been carried out to evaluate the thermally induced frequency shift in RFQ. Cooling parameters have been optimized to minimize frequency shift.
Vacuum System design
Vacuum System
Vacuum system has been designed for individual RFQ modules, each module comprising of two segments of 1 meter each. The gas loads which the vacuum system has to deal with for RFQ are :
- Gas load due to outgassing of the internal surface of the RFQ (OFE Copper) .
- LEBT/ Ion source Gas load .
- Gas load resulting from proton loss .
Each module will include one pumping station, which will have Turbo molecular pumps/ cryopumps of capacity 500 l/s and 2000 l/s respectively.
Prototype RFQ Fabrication
Vane Modulation Trials
Trials for generating vane modulations on the RFQ vane tip were conducted in the RRCAT workshop on a CNC Horizontal Boring Machine using Ball Endmill Cutter.
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Vane modulation trial on the CNC Horizontal Jig Boring Machine |
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1200 mm long extruded and deep hole drilled aluminium alloy rods |
Prototype RFQ machining
The machining of first segment of RFQ in Aluminium Alloy 6061 T6 is in progress at a local machine shop. The prototype will help in understanding the criticalities involved in the machining and will also help in verifying Physics design by performing low power RF characterization.
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Vane machining in progress |
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3D Model of First segment of RFQ |
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