arXiv subjects

S. Nagaitsev

Publications and source records attributed to S. Nagaitsev.

64 records · Page 4Linked to original sources

arXiv2012

A new approach to calculate the transport matrix in RF cavities

A realistic approach to calculate the transport matrix in RF cavities is developed. It is based on joint solution of equations of longitudinal and transverse motion of a charged particle in an electromagnetic field of the linac. This field is a given by distribution (measured or calculated) of the component of the longitudinal electric field on the axis of the linac. New approach is compared with other matrix methods to solve the same problem. The comparison with code ASTRA has been carried out. Complete agreement for tracking results for a TESLA-type cavity is achieved. A corresponding algorithm will be implemented into the MARS15 code.

physics.acc-ph↗

arXiv2012

A search for integrable four-dimensional nonlinear accelerator lattices

Integrable nonlinear motion in accelerators has the potential to introduce a large betatron tune spread to suppress instabilities and to mitigate the effects of space charge and magnetic field errors. To create such an accelerator lattice one has to find magnetic and/or electric field combinations leading to a stable integrable motion. This paper presents families of lattices with one invariant where bounded motion can be easily created in large volumes of the phase space. In addition, it presents two examples of integrable nonlinear accelerator lattices, realizable with longitudinal-coordinate-dependent magnetic or electric fields with the stable nonlinear motion, which can be solved in terms of separable variables.

physics.acc-ph↗

arXiv2012

Superfluid helium testing of a stainless steel to titanium piping transition joint

Stainless steel-to-titanium bimetallic transitions have been fabricated with an explosively bonded joint. This novel joining technique was conducted by the Russian Federal Nuclear Center, working under contract for the Joint Institute for Nuclear Research. These bimetallic transitions are being considered for use in future superconducting radio-frequency cavity cryomodule assemblies. This application requires cryogenic testing to demonstrate that this transition joint remains leak-tight when sealing superfluid helium. To simulate a titanium cavity vessel connection to a stainless steel service pipe, bimetallic transition joints were paired together to fabricate piping assemblies. These piping assemblies were then tested in superfluid helium conditions at Fermi National Accelerator Laboratory test facilities. The transition joint test program will be described. Fabrication experience and test results will be presented.

physics.acc-ph↗

arXiv2012

Project X functional requirements specification

Project X is a multi-megawatt proton facility being developed to support a world-leading program in Intensity Frontier physics at Fermilab. The facility is designed to support programs in elementary particle and nuclear physics, with possible applications to nuclear energy research. A Functional Requirements Specification has been developed in order to establish performance criteria for the Project X complex in support of these multiple missions, and to assure that the facility is designed with sufficient upgrade capability to provide U.S. leadership for many decades to come. This paper will briefly review the previously described Functional Requirements, and then discuss their recent evolution.

physics.acc-ph↗

arXiv2012

Ring for test of nonlinear integrable optics

Nonlinear optics is a promising idea potentially opening the path towards achieving super high beam intensities in circular accelerators. Creation of a tune spread reaching 50% of the betatron tune would provide strong Landau damping and make the beam immune to instabilities. Recent theoretical work has identified a possible way to implement stable nonlinear optics by incorporating nonlinear focusing elements into a specially designed machine lattice. In this report we propose the design of a test accelerator for a proof-of-principle experiment. We discuss possible studies at the machine, requirements on the optics stability and sensitivity to imperfections.

physics.acc-ph↗

arXiv2012

Project X functional requirements specification

Project X is a multi-megawatt proton facility being developed to support intensity frontier research in elementary particle physics, with possible applications to nuclear physics and nuclear energy research, at Fermilab. A Functional Requirements Specification has been developed in order to establish performance criteria for the Project X complex in support of these multiple missions. This paper will describe the Functional Requirements for the Project X facility and the rationale for these requirements.

physics.acc-ph↗

arXiv2012

Recent advances in Ti and Nb explosion welding with stainless steel for 2K operating (ILC Program)- To the proceedings of LCWS11

The world first samples 0f Ti+SS and Nb+SS joints were manufactured by an explosion welding technology demonstrating a high mechanic properties and leak absence at 4.6 x 10^{-9} atm-cc/sec. Residual stresses in bimetallic joints resulting from explosion welding measured by neutron diffraction method are quite high (~1000 MPa). Thermal tempering of explosion welded Ti+SS and Nb+SS specimens leads to complete relaxation of internal stresses in Ti,Nb and Stainless steel and makes the transition elements quite serviceable.

physics.ins-det↗

arXiv2011

Nonlinear Integrable Ion Traps

Quadrupole ion traps can be transformed into nonlinear traps with integrable motion by adding special electrostatic potentials. This can be done with both stationary potentials (electrostatic plus a uniform magnetic field) and with time-dependent electric potentials. These potentials are chosen such that the single particle Hamilton-Jacobi equations of motion are separable in some coordinate systems. The electrostatic potentials have several free adjustable parameters allowing for a quadrupole trap to be transformed into, for example, a double-well or a toroidal-well system. The particle motion remains regular, non-chaotic, integrable in quadratures, and stable for a wide range of parameters. We present two examples of how to realize such a system in case of a time-independent (the Penning trap) as well as a time-dependent (the Paul trap) configuration.

physics.atom-ph↗

arXiv2010

Nonlinear Accelerator Lattices with One and Two Analytic Invariants

Integrable systems appeared in physics long ago at the onset of classical dynamics with examples being Kepler's and other famous problems. Unfortunately, the majority of nonlinear problems turned out to be nonintegrable. In accelerator terms, any 2D nonlinear nonintegrable mapping produces chaotic motion and a complex network of stable and unstable resonances. Nevertheless, in the proximity of an integrable system the full volume of such a chaotic network is small. Thus, the integrable nonlinear motion in accelerators has the potential to introduce a large betatron tune spread to suppress instabilities and to mitigate the effects of space charge and magnetic field errors. To create such an accelerator lattice one has to find magnetic and electrtic field combinations leading to a stable integrable motion. This paper presents families of lattices with one invariant where bounded motion can be easily created in large volumes of the phase space. In addition, it presents 3 families of integrable nonlinear accelerator lattices, realizable with longitudinal-coordinate-dependent magnetic or electric fields with the stable nonlinear motion, which can be solved in terms of separable variables.

physics.acc-ph↗

arXiv2000

The Flat Beam Experiment at the FNAL Photoinjector

A technique for production of an electron beam with a high transverse emittance ratio. a "flat" beam, has been proposed by Brinkmann, Derbenev, and Floettmann.[1] The cathode of an RF-laser gun is immersed in a solenoidal magnetic field; as a result the beam emitted from a round laser spot has a net angular momentum. Subsequent passage through a quadrupole channel that has a 90 degree difference in phase advance between the transverse degrees of freedom results in a flat beam. Experimental study is underway at the Fermilab A0 Photoinjector. Thus far, transverse emittance ratios as high as 50 have been observed, and the results are in substantial agreement with simulation. [1] R. Brinkmann, Ya. Derbenev, K. Floettmann, "A Flat Beam Electron Source for Linear Colliders." TESLA Note 99-09, April 1999.

physics.acc-ph↗