Simulation And Study Of Injection Method Of Barrier Bucket Supported By Off-aligned Electron Cooling On CRing

HIAF(High Intensity Heavy Ion Accelerator Facility) project is a significant infrastructure of science approved by the Institute of Modern Physics in the12 th Five-Year Plan period, which aims at exploring the limitation of nucleus existence, the structure of exotic nuclei, the generating mechanism of nuclei from Fe to U. HIAF is an advanced heavy ion science research facility for multifunction, one of which is high energy density physics. By focusing simultaneously in transverse and longitudinal directions, the high intensity ion beam is transferred to fixed target. The energy of the beam releases in a tiny volume, generating a special matter state whose energy density exceeds 1011J/m3 and pressure exceeds 100 GPa, which can be used to simulate the moment of fusion ignition and interior of large planet. In this way, physicists can research the phase change,equation of state, hydromechanics in extreme conditions.CRing needs to provide a high intensity of up to 5×1011ppp238U34+for High energy density physics research, while the traditional Bucket to Bucket injection method cannot fulfill the demand. An injection method, Barrier Bucket(BB)supported by electron cooling, is proposed based on the successful applications in Fermilab for antiproton stacking. The Barrier Bucket injection method stacks beam in longitudinal phase space, overcoming the limitation of intensity gain due to circumference ratio between synchrotrons. The off-aligned electron cooling cools the longitudinal phase space down to improve the efficiency of stacking and suppress the over-cooling phenomenon during stacking process to avoid beam loss due to space charge effect.Firstly, the thesis derives the physics theory and model related to Barrier Bucket beam stacking: 1. The algorithm for large step longitudinal motion is derived based on the longitudinal dynamics in sinusoidal Barrier Bucket voltage and programmed to a library function of BETACOOL; 2. The impact of off-aligned angle on cooling process and transverse emittance is analyzed based on the average variants of C-S parameter in single turn. The effectiveness of suppression of space charge effect by off-alignment is proved; 3. During the cooling process, the transverse distribution of ion beam does not follow Gaussian type. Analytic formula is not suitable for the calculation of space charge effect any more. The incoherent tune shift duo to space charge effect is derived from parameter equation by solving and integrating of differential phase advance. A new code for tune spread calculation is finished based on the module of 2D space charge force solver in BEAMPATH program. The impact of space charge effect on stability of beam is evaluated with the new code.Secondly, the thesis researches the key parameters in beam stacking of CRing with numerical simulation: 1. The impact of beam quality of BRing on stacking process in CRing is analyzed. To ensure the efficiency of beam stacking in CRing,a beam stacking scheme of multiple multi-turn is proposed to improve the quality of beam extracted from BRing. 2. The stacking scheme and cooling scheme of CRing are discussed. The key parameters impacting the stacking efficiency, such as electron beam current, off-aligned angle and BB voltage, are researched in detail by improved BETACOOL. As an optimized result, a approximate beam intensity of 5.79 × 1011 ppp is acquired through 6 injections. The stacking goal of CRing is achieved.