Elaborated Modeling of Synchrotron Motion in Vlasov-Fokker-Planck Solvers

Solving the Vlasov-Fokker-Planck equation is a well-tested approach to simulate dynamics of electron bunches self-interacting with their own wake-field. Typical implementations model the dynamics of a charge density in a damped harmonic oscillator, with a small perturbation due to collective effects. This description imposes some limits to the applicability: Because after a certain simulation time coherent synchrotron motion will be damped down, effectively only the incoherent motion is described. Furthermore – even though computed - the tune spread is typically masked by the use of a charge density instead of individual particles. As a consequence, some effects are not reproduced. In this contribution, we present methods that allow to consider single-particle motion, coherent synchrotron oscillations, non-linearities of the accelerating voltage, higher orders of the momentum compaction factor, as well as modulations of the accelerating voltage. We also provide exemplary studies – based on the KIT storage ring KARA (KArlsruhe Research Accelerator) - to show the potentiality of the methods

Paliperidone extended-release: does it have a place in antipsychotic therapy?

Paliperidone (9-hydroxy-risperidone), the active metabolite of risperidone, was approved for treating schizophrenia worldwide in 2006 as paliperidone extended-release (PER), and became the first second-generation antipsychotic specifically licensed for treating schizoaffective disorder in 2009. However, at the same time, its comparatively high cost gave rise to concerns about the cost-effectiveness of PER as compared with its precursor, risperidone. This paper reviews the existing knowledge of the pharmacology, kinetics, efficacy, tolerability, and fields of application of PER, and compares PER with risperidone in order to determine whether it has a place in antipsychotic therapy. An independent assessment of all relevant publications on PER published until July 2010 was undertaken. PER has a unique pharmacological profile, including single dosing, predominantly renal excretion, low drug–drug interaction risk, and differs from risperidone in terms of mode of action and pharmacokinetics. High-level evidence suggests that PER is efficacious and safe in schizophrenia, schizoaffective disorder, and acute manic episodes. There is a striking lack of published head-to-head comparisons between PER and risperidone, irrespective of indication. Low-level evidence shows a lower risk for hyperprolactinemia and higher patient satisfaction with PER than with risperidone. PER adds to the still limited arsenal of second-generation antipsychotics. In the absence of direct comparisons with risperidone, it remains difficult to come to a final verdict on the potential additional therapeutic benefits of PER which would justify its substantially higher costs as compared with risperidone. However, in terms of pharmacology, the available evidence cautiously suggests a place for PER in modern antipsychotic therapy

Studies of the Micro-Bunching Instability in the Presence of a Damping Wiggler

At the KIT storage ring KARA (Karlsruhe Research Accelerator), the momentum compaction factor can be reduced leading to natural bunch lengths in the ps range. Due to the high degree of longitudinal compression, the micro-bunching instability arises. During this longitudinal instability, the bunches emit bursts of intense coherent synchrotron radiation in the THz frequency range caused by the complex longitudinal dynamics. The temporal pattern of the emitted bursts depends on given machine parameters, like momentum compaction factor, acceleration voltage, and damping time. In this paper, the influence of the damping time is studied by utilizing the CLIC damping wiggler prototype installed in KARA as well as by simulations using the Vlasov-Fokker-Planck solver Inovesa

Studies of the Micro-Bunching Instability in the Presence of a Damping Wiggler

At the KIT storage ring KARA (Karlsruhe Research Accelerator), the momentum compaction factor can be reduced leading to natural bunch lengths in the ps range. Due to the high degree of longitudinal compression, the micro-bunching instability arises. During this longitudinal instability, the bunches emit bursts of intense coherent synchrotron radiation in the THz frequency range caused by the complex longitudinal dynamics. The temporal pattern of the emitted bursts depends on given machine parameters, like momentum compaction factor, acceleration voltage, and damping time. In this paper, the influence of the damping time is studied by utilizing the CLIC damping wiggler prototype installed in KARA as well as by simulations using the Vlasov-Fokker-Planck solver Inovesa