1. November 7, 2008 The meeting on RIKEN AVF Cyclotron Upgrade Progress report on activity plan
Sergey Vorozhtsov

2. Table of contents CYCLOTRON COMPUTER MODEL DEVELOPMENT AXIAL INJECTION
Electromagnetic field
Beam dynamics
Simulation calibration
AXIAL INJECTION
Buncher
Inflector
Electrostatic quadruple
CENTRAL REGION
16O7+ ions
14N5+ ions
ACCELERATION
EXTRACTION
October 31, 2008
Sergey Vorozhtsov

3. Cyclotron computer model development
Electromagnetic field
Completion in general the model
Simulate the electrostatic field of an electric quadruple at the immediate upstream of the inflector.
Calculate the electrostatic field of a new inflector shape, including the optimal electrode cutting.
Beam dynamics
Introduction into the beam dynamics model:
The 1st trim coil average field contribution to shift of the particle RF phase to the top of the RF voltage during acceleration.
Main and deflector probes for the beam position & emittances readings.
Phase defining slits at the 1st turn.
Make the CBDA code to calculate the acceptance of the AVF cyclotron
Simulation calibration
Compare once again the simulation and the experiment with respect to the beam position, beam width, injection efficiency, etc.
To get better calibration of the simulations vs experiment.
Taking into account the recent corrections in the input data of the acceleration regimes:
Corrected injection emittances.
Midplane magnetic field with GLs impact etc.
Compare by simulations the nominal and optimal regimes for the same values of the injection emittances
Additional cross-check the CBDA code (including the beam space charge and higher order effects evaluation in the LEBT) against other similar existing program (TRACE 3D, PBO Lab etc).
October 31, 2008
Sergey Vorozhtsov

4. Axial injection Further development of the LEBT redesign proposal
Buncher
Introduction a chopper upstream the buncher to clean up the injected beam in the cyclotron central region
Optimization the buncher voltages and phases of 1f, 2f and 3f harmonics
Optimization of the phasing between buncher and Dee voltages to get better injection efficiency
Estimation of the effect of two bunchers (Linear buncher – upstream and Sin buncher – downstream) in the LEBT
Recalculation the LEBT SC effects for corrected buncher field distribution.
Inflector
Optimization the inflector voltage and its position
The operation inflector voltage is 3.15 kV
Decrease of the existing ion axial losses by the inflector axial shift on 2.3 mm
Study a new inflector shape
Optimization of the inflector electrode cutting
Continue beam space charge effects impact estimation: FFT for inflector curvilinear surfaces.
Electrostatic quadruple
Simulate the effect of an electric quadruple at the immediate upstream of the inflector on the beam quality
Some space for the installation of an electric quadruple at the immediate upstream of the inflector was found! An electric quadruple of ~15 mm in bore diameter and several mm in length could be placed there. Checking by simulations whether it is effective or not
Initial variant: Simulate to understand whether or not the injection efficiency is improved drastically when an electrostatic quadruple with a radius and length of, say 15 mm and 20 mm, respectively, is installed after the inflector, i.e. at the position of the phase slit
October 31, 2008
Sergey Vorozhtsov

5. Central region. 16O7+ ions
Investigation of the possibility to increase the maximal energy of 16O7+ ions
Estimation of the maximum feasible ion energy for existing central electrode structure and achieved presently dee voltage (~50 kV).
RF frequency =(?) MHz (h=2 RF harmonic), Inflector voltage=2.30 KV
Modification of the central electrode structure to obtain the requested MeV/A ion energy under limited dee voltage (below 50 kV).
RF frequency =20.4 MHz (h=2 RF harmonic), Inflector voltage=3.68 k V
October 31, 2008
Sergey Vorozhtsov

6. Central region. 14N5+ ions
Complete the design of the optimal geometry of the center region for the existing regime (h=2). For that purpose, it would be important to make the CBDA code to calculate the acceptance of the AVF
Isochronous field shaping for the test particle taking into account the impact of the Glaser lenses on the central region midplane field distribution
Cyclotron midplane distortion due to Glaser lenses impact.
Estimation of the horizontal magnetic field in the midplane.
Assessment of the amplitude of the particle axial oscillation to the above mentioned midplane distortion.
The harmonic coil insertion into the cyclotron electromagnetic field computer model with the corresponding shimming of the lower order magnetic field harmonics
to improve the radial quality of the beam
To provide turn separation at the extraction
Beam space charge effects impact estimation
Optimization the beam centering by variation of the dee voltages independently for each dee
The backward 6D matching, i.e. obtaining the prescribed phase space out of the inflector in order to get a matched beam during acceleration
October 31, 2008
Sergey Vorozhtsov

7. Acceleration. 16O7+ ions
Reference particle acceleration until the mouth o the ESD to obtain the requested MeV/A ion energy under limited dee voltage (49 kV).
RF frequency =20.4 MHz (h=2 RF harmonic), Inflector voltage=3.68 k V
October 31, 2008
Sergey Vorozhtsov

8. Acceleration. 14N5+ ions
Adjustment of the isochronous magnetic field distribution in the whole working radii range by variation of the trim coil currents only:
The RF frequency was fixed at 16.3 MHz to get the given energy
October 31, 2008
Sergey Vorozhtsov

9. Extraction Launch extraction process simulation
Calculation the extraction orbit in the deflector when a beam enters it with an inclined angle of ~ 10 mrad
Take into account the 3D modeling results of the extraction system electromagnetic field
Computer modeling of the EMC field
The parameters of the starting point of extraction orbit in the nominal regime are as follows:
Energy = 7.02 MeV/u, X = 728 mm, Y = -11 mm
The position of the entrance of the deflector is X= 728 mm and Y = 0 mm.
PX = 563 MeV/c, PY = 1603 MeV/c
The data on the extraction orbit, from which the curvature of the deflector was determined, is available as Excel file..
October 31, 2008
Sergey Vorozhtsov

10. Back up slides

11. October 31, 2008
Sergey Vorozhtsov

12. October 31, 2008
Sergey Vorozhtsov