November 14, 2008 The meeting on RIKEN AVF Cyclotron Upgrade Progress report on activity plan Sergey Vorozhtsov

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 November 14, 2008 Sergey Vorozhtsov

Cyclotron computer model development (1) 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 November 14, 2008 Sergey Vorozhtsov

Cyclotron computer model development (2) 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 Inflector and central region orbits to compere with other codes higher order effects evaluation in the LEBT) against other similar existing program (TRACE 3D, PBO Lab etc). November 14, 2008 Sergey Vorozhtsov

Axial injection(1) Further development of the LEBT redesign proposal Estimation of the buncher and GL-I37, GL-I38 parameters for oxygen injection using A/Z scaling law and nitrogen data 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. November 14, 2008 Sergey Vorozhtsov

Axial injection (2) 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. November 14, 2008 Sergey Vorozhtsov

Axial injection (3) 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 November 14, 2008 Sergey Vorozhtsov

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 11.044 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 November 14, 2008 Sergey Vorozhtsov

Central region. 14N5+ ions (1) 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 due to the above mentioned midplane distortion. November 14, 2008 Sergey Vorozhtsov

Central region. 14N5+ ions (2) The harmonic coil insertion into the cyclotron electromagnetic field computer model => shimming of the lower order magnetic field harmonics to improve the radial quality of the beam 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 => to get a matched beam during acceleration November 14, 2008 Sergey Vorozhtsov

Acceleration. 16O7+ ions Reference particle acceleration until the mouth o the ESD to obtain the requested 11.044 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 Acceleration of bunch and assessment of losses from the buncher entrance until the initial turns November 14, 2008 Sergey Vorozhtsov

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 Acceleration of bunch and assessment of losses from the buncher entrance until the initial turns November 14, 2008 Sergey Vorozhtsov

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 Recalculating the ESD field for 6 mm horizontal aperture (instead of previous 8 mm) Computer modeling of the EMC field The harmonic coil insertion into the cyclotron electromagnetic field computer model to provide turn separation at the extraction November 14, 2008 Sergey Vorozhtsov

Back up slides

November 14, 2008 Sergey Vorozhtsov

November 14, 2008 Sergey Vorozhtsov