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Consideration of transverse wakefields and impedances due to the tapered vacuum chambers for superconducting mini-gap undulators revealed the existence of trapped modes. To investigate this phenomenon, a series of analytical and numerical calculations were performed for both elliptical and rectangular chambers. A rectangular prototype was built and measured and the experimental results were found to be in very good agreement with theory. Knowledge about the impedance of tapered vacuum chambers is important for the evaluation of transverse instabilities in high-energy accelerators.

The NSLS-II storage ring has been commissioned during Phase 1 with 500 MHz 7-cell PETRA-III RF cavity. In this paper we present our first beam-measured data on instabilities and collective effects with a normal conducting RF system., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The optimal values for tillage quality are proved to be highly dependent on harvest prices and inputs to obtain the required tillage quality, with an abstract model of the tillage quality being elaborated to establish the existing levels of optimal tillage quality that is highly dependent on harvest prices and the inputs to prepare the soil.

We discuss coupled-bunch instabilities thresholds for the NSLS-II Storage Ring. In particular, we analyze thresholds from the High Order Modes (HOMs) of the PETRA-III 7-cell cavity. Beam dynamics simulations with the code OASIS, using the measured HOMs, will be compared with machine studies., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

It has been established experimentally that the force of cutting feed grain with optimal sharpening angles of the cutting element and pinch angle during a change in the cutting speed from 22 to 46 m/s increases by 1.2 times and for rape seeds by 1.1 times.

В работе рассмотрена инвариантность моделей механизма управления научно-техническими и социально-организационными системами в проблемных ситуациях на базе прототипов и предложенных решений. Предлагаются блок-схемы функционирования системы анализа ситуации и проектирования ее решения, функционирования системы управления и интеграционной поддержки. Разработана методика оценки инвариантности развитого и базового механизма управления научно-техническими и социально-организационными системами в проблемных ситуациях. Invariance of the models of science-and-technical and social-organizational systems management mechanism in problem situations on the basis of prototypes and ready-made solutions is under the authors attention. Block-schemes of functioning of the system of situation analysis and its decision, and functioning of management and integration support system are put forward. The methodology of invariance assessment of developed and basic mechanisms of science-and-technical and social-organizational systems in problem situations is worked out.

Examples of determination of optimal soil cultivation depth during grain production are considered. Obtained mathematical model permits to determine optimal soil cultivation depth in specific environmental and economic conditions.

National Synchrotron Light Source II (NSLS-II), a new state-of-the-art third-generation light source under construction at Brookhaven National Laboratory is expected to have extremely small emittance and extraordinary beam stability. The mechanical requirements for beam diagnostics and instrumentation are exceptionally challenging. Here we present an overview of the mechanical aspects of some NSLS-II diagnostics as well as the performance levels of some systems currently under development.

We use the program ECHO to study numerically the loss factor of axisymmetric cavities and collimators with and without tapering. We consider a Gaussian driving bunch of length $\ensuremath{\sigma}$, and structures with inner radius $b$, outer radius $d$, cavity gap (or collimator inner length) $g$, and taper length $L$. In all cases we consider a short bunch with $\ensuremath{\sigma}\ensuremath{\ll}b$. For the untapered structures ($L=0$), in certain regimes, we describe our numerical results using the known expressions for a step transition and for the diffraction model. In addition, we identify new regimes where $gl\ensuremath{\sigma}$ and/or $d\ensuremath{-}bl\ensuremath{\sigma}$, for which the data must be described by new phenomenological expressions. For a tapered collimator with $d\ensuremath{-}bgb$, we present a phenomenological formula which accurately describes the dependence of the loss factor on the parameters $\ensuremath{\sigma}$, $b$, $d$, and $L$. This formula also holds for a tapered cavity with $gg{d}^{2}/\ensuremath{\sigma}$ and $d\ensuremath{-}bgb$.

Booster extraction presents a number of problems that include strengths and waveforms of the pulsed magnets and design of the vacuum chamber. Instabilities in the booster extraction may compromise the extracted beam quality deteriorating value of high-performance injector design. Here we discuss requirements and tolerances for the extraction system components and methods of increasing its performance., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

We discuss status and plans of development of the NSLS-II injector. The injector consists of 200 MeV linac, 3-GeV booster, transport lines and injection straight section. The system design is now nearly completed and the injector development is in the procurement phase. The injector commissioning is planned to take place in 2012., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

Rectangular-waveguide devices intended for the withdrawal and absorption of high-order modes (HOMs) from the superstructure of the TESLA linear electron–positron collider are investigated. These devices, known as couplers, are set in between the subcavities of the superstructure and at its ends. The HOM couplers investigated are connected to the drift tubes via slots oriented along the tube axis (longitudinal slots), at right angles to the axis (azimuthal slots), and at an angle to the axis. In order to damp the HOMs of both polarizations, two rectangular waveguides are used for each coupler. The results of calculation and experimental investigation of two copper subcavities of the superstructure, each one consisting of seven cells, are presented. The investigations were conducted at room temperature at a frequency of 3 GHz using models.

The wakefield and impedance produced by the components of the NSLS-II storage ring have been computed for an electron bunch length of 3 mm rms. The results are summarized in a table giving for each component, the loss factor (kappapar ), the imaginary part of the longitudinal impedance at low frequency divided by the revolution harmonic (ImZpar/n), and the transverse kick factors (kappax,kappay).

A new high-brightness synchrotron light source (NSLS-II) is under design at BNL. The 3-GeV NSLS-II storage ring has a double-bend achromatic lattice with damping wigglers installed in zero-dispersion straights to reduce the emittance below 1 nm. In this paper, we present an overview of the impact of collective effects upon the performance of the storage ring. Subjects discussed include instability thresholds, Touschek lifetime and intra-beam scattering.

RF system requirements are derived from machine parameters and beam stability specifications. The conceptual design of the RF system for NSLS-II to meet these requirements is presented, consisting of 500 MHz superconducting main cavities, 1500 MHz pasive SCRF harmonic cavities for bunch lengthening, and the RF power and cryogenic systems..

CESR-B type superconducting cavities are under consideration for acceleration of the electron beam in the 3 GeV NSLS-II storage ring. In this paper we present detailed investigation of longitudinal and transverse impedance of CESR-B cavity and transitions. Ferrite material is included in impedance analysis. Its effect on short range wakepotential has been studied using GdfidL code. The summary results of loss factors and kick factors are presented for a 3 mm rms bunch length.

In this paper we discuss computation of the coupling impedance of the vacuum chambers for the NSLS-II storage ring using the electromagnetic simulator GdfidL [1]. The impedance of the vacuum chambers depends on the geometric dimensions of the cross-section and height of the slot in the chamber wall. Of particular concern is the complex geometry of the infrared extraction chambers to be installed in special large-gap dipole magnets. In this case, wakefields are generated due to tapered transitions and large vertical-aperture ports with mirrors near the electron beam.

This paper describes plans to upgrade insertion devices (IDs) at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, U.S.A. The aging wiggler (W120) at X25 is being replaced by a 1 m long in-vacuum mini-gap undulator (MGU-X25) optimized for a dedicated macromolecular crystallography program. A new, 1/3 m long, undulator (MGU or SCU-X9), will be installed between a pair of RF cavities at X9, and will serve a new beamline dedicated for small angle x-ray scattering (SAXS). Both IDs will have provision for cryocooling the NdFeB hybrid arrays to 150K to raise the field and K-value and to obtain better spectral coverage. Design issues of the devices and other considerations, especially magnetic measurement at low temperature, will be discussed.

The vertical impedances of the preliminary designs of National Synchrotron Light Source II (NSLS-II) Mini Gap Undulators (MGU) are calculated by means of GdfidL code. The Transverse Mode Coupling Instability (TMCI) thresholds corresponding to these impedances are estimated using an analytically solvable model.

The National Synchrotron Light Source at BNL was the first dedicated light source facility and it has now operated for more than 20 years. During this time the user community has grown to more than 2400 users annually. To insure that this vibrant user community has access to the highest quality photon beams, the NSLS is pursuing the design of a new ultra-high brightness (∼1021) electron storage ring, tailored to the 0.3-20 KeV photon energy range. We present our preliminary design and review the critical accelerator physics design issues.

NSLS-II is a 3 GeV ultra-high brightness storage ring planned to succeed the present NSLS rings at BNL. Ultra-low emittance combined with short bunch length means that it is critical to minimize the effects of Touschek scattering and coherent instabilities. Improved lifetime and stability can be achieved by including a third-harmonic RF cavity in the baseline design. This paper describes the required harmonic RF parameters and the expected system performance.

Die Arbeit behandelt eine planare 30 GHz Beschleunigerstruktur als neue Alternative zu einer Struktur, die im Compact Linear Collider (CLIC) beim Forschungszentrum CERN in Genf angewendet wird. Die Anforderungen an die planare Beschleunigerstruktur entsprechen dabei den Anforderungen an die CLIC-Struktur. Zur Verbesserung ihrer HF-Eigenschaften mussten zwei wichtige Aufgaben gelöst werden: 1) Die Dämpfung von höheren Moden und 2) die Steigerung der Durchschlagsfestigkeit auf der Irisoberfläche der Resonator. Zur Feststellung des Einflusses der höheren Moden wurde das transversale Wakepotential berechnet. Entsprechend den Anforderungen muss es für einen zeitlichen Abstand zwischen den Ladungspaketen von 0.67 ns um den Faktor 100 unterdrückt werden. Für die numerischen Simulationen wurde das 3-dimensionale Feldberechnungsprogramm GdfidL verwendet. Zur Unterdrückung der höheren Moden wurden zwei Strukturvarianten entwickelt, die den obigen Forderung entsprechen, erstens eine Struktur bestehend aus einer Kombination von Dämpfungshohlleitern zweitens eine verstimmte Struktur. Zur Verminderung der hohen Feldstärke auf der Irisoberfläche der Koppelzellen wurde eine symmetrische Ein- und Auskoppeleinrichtung verwendet, bei welcher die HF-Leistung symmetrisch eingespeist wird. Zur Steigerung der Duchschlagsfestigkeit der Struktur wurde eine abgerundete Irisform vorgeschlagen. Zur messtechnischen Überprüfung im Laboratorium wurde ein auf 10 GHz skaliertes Modell der Struktur mit konstanter Impedanz hergestellt. Die Messergebnisse stimmten hierbei mit den numerischen Simulationen sehr gut überein.

We propose an approach to the optimization of segmented in-vacuum undulators, in which different segments along an undulator may have different gaps and periods. This enables close matching between the gaps and the vertical "envelope" of electron beam motion in a storage ring straight section (carefully satisfying the associated vertical "stay clear" constraint) and, at the same time, precise tuning of all the segments to the same fundamental photon energy. Placing together undulator segments with different periods may introduce small kicks to electron trajectories at the segment junctions, which can be easily compensated, without introducing any significant radiation phase error, by active correction magnets or by special design of terminating magnets in the segments. Thanks to this, the entire multi-segment structure can operate as one long undulator. On the other hand, since the vertical gaps in segments located close to straight section center can be smaller than at extremities, such structure can offer better magnetic performance, compared to the case of a standard undulator with constant gap (and period) over its length. We present magnetic field, radiation flux and brightness calculation results for such segmented adaptive-gap in-vacuum undulators if used in low-beta straight sections of NSLS-II, and demonstrate their gain in spectral performance, especially in hard X-ray range, over standard room-temperature and even cryo-cooled in- vacuum undulators.