Proposed High-Current rf Linear Accelerators with Beams in Thermal Equilibrium

An accelerator-driven subcritical system (ADS) program was launched in China in 2011, which aims to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power in multiple phases lasting about 20 years. The driver linac is defined to be 1.5 GeV in energy, 10 mA in current and in cw operation mode. To meet the extremely high reliability and availability, the linac is designed with much installed margin and fault tolerance, including hot-spare injectors and local compensation method for key element failures. The accelerator complex consists of two parallel 10-MeV injectors, a joint mediumenergy beam transport line, a main linac, and a high-energy beam transport line. The superconducting acceleration structures are employed except for the radio frequency quadrupole accelerators (RFQs) which are at room temperature. The general design considerations and the beam dynamics design of the driver linac complex are presented here.

Section: Beam Dynamics Designmentioning

confidence: 99%

Physics design of an accelerator for an accelerator-driven subcritical system

Cheng

Geng

et al. 2013

“…In Ref. [7] a theoretical foundation in terms of a Vlasov-Poisson eigenmode analysis was presented to respond to the discussion of whether anisotropic space charge dominated beams must approach energy equipartition as ''thermodynamics,'' if applicable to beams, would suggest [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Space charge resonances in two and three dimensional anisotropic beams

Hofmann

Franchetti

Boine‐Frankenheim

et al. 2003

The theory and simulation of coherent resonant coupling due to space charge in coasting or bunched anisotropic equilibrium beams is presented. Our work confirms that analytical results on coherent oscillations and instabilities of anisotropic KV (Kapchinskij-Vladimirskij) distributions are a valid tool to interpret the findings from 2D and 3D self-consistent particle-in-cell simulations for both KV and waterbag distributions. With reference to rings we discuss space charge coherent tune shifts up to fourth order and introduce a coherent coupled mode coefficient, which enables us to resolve the issue of KV anomalies by relating them to negative energy modes. The second emphasis of this study is with reference to linacs and a detailed discussion of ''stability charts'' describing resonant regions where approach to equipartition may occur.

“…While conventional designs of such machines lead to bunches that are out of equilibrium, a design strategy that keeps the beam at or near thermal equilibrium has been formulated [12]. The principal motivation for this alternative strategy is to circumvent equipartitioning processes that cause emittance growth and halo formation.…”

Section: Introductionmentioning

confidence: 99%

Chaotic orbits in thermal-equilibrium beams: Existence and dynamical implications

Bohn

Sideris

2003

Phase mixing of chaotic orbits exponentially distributes these orbits through their accessible phase space. This phenomenon, commonly called ''chaotic mixing,'' stands in marked contrast to phase mixing of regular orbits which proceeds as a power law in time. It is operationally irreversible; hence, its associated e-folding time scale sets a condition on any process envisioned for emittance compensation. A key question is whether beams can support chaotic orbits, and if so, under what conditions? We numerically investigate the parameter space of three-dimensional thermal-equilibrium beams with space charge, confined by linear external focusing forces, to determine whether the associated potentials support chaotic orbits. We find that a large subset of the parameter space does support chaos and, in turn, chaotic mixing. Details and implications are enumerated.