Alexander Durkin

The LIDOS.RFQ.Designer development

The LIDOS.RFQ.Designer code package gives users the possibility to proceed successfully from input data up to RFQ channel design and space-charge-dominated beam simulation. The codes main feature is that it displays the maximum scientific visualization for each calculation step. The package contains codes with three levels of mathematical model complexity. The first-level codes not only make a preliminary choice of the main parameter arrays on the basis of a simplified physical model but also choose the design optimization. The case of high-current CW RFQ radiation purity (minimum of lost particles) is considered as the main optimization criteria. The second-level codes are used for RF field calculations, taking into account the real shape of the RFQ vanes. The third-level codes are based on complex PIC-models that are needed for beam simulation in the chosen channel version.

Emittance growth and halo formation in charge‐dominated beams

The optimization of high‐current high‐energy linacs against the low beam loss requirement is not straightforward or well‐codified. Outlying particle losses at the 10−5 up to 10−8 level might have only a small effect on the rms properties of the beam, and thus the total beam size must be constantly kept under observation. RMS‐physics has gained wide‐spread acceptance as a necessary design tool, but its sufficiency is an issue for ATW/ABC accelerators.

Non-Coulomb perturbations influence on beam dynamics in extended accelerating/focusing channels

It is generally taken that the main source of particle losses in extended linac channel is the Coulomb field of space charge dominated beam. However, there are the non-Coulomb effects concerned with external field perturbations (external perturbations) and their influence on beam dynamic is comparable with the action of space charge. The calculation of the accelerating/focusing channel always based on the specific mathematical model involving description of external accelerating and focusing forces. In this model as a rule, the focusing field linear dependence on transverse coordinates and accelerating field axis distribution is used. The channel based on such models will be called ideal. Of course, there are no unprojected losses in the ideal channel.

SCD-beam main regularities in beginning part of high-current proton linac

Space charge-dominated (SCD) beam main regularities in the beginning part of high-current proton linac are presented. Charge redistribution during beam transport and bunching are considered. Code tools ZHALO and KERN+HALO are used for physical process better understanding and scientific visualization of different factor influence on SCD-beam transport and bunching.

Design of high-energy high-current linac with focusing by superconducting solenoids

The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac is presented in the report. In new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channel features allow to decrease beam matched radius and increase a linac radiation purity without aperture growth. ‘‘Regotron’’ is used as high power generator in linac main part. But D&W cavities need not be divided into sections connected by RF‐bridges which denuded them of high coupling factor.

Main regularities of particle redistribution in space charge dominated beam transport and bunching

The main features of beam charge redistribution during high-current beam transporting and bunching is discussed.