Thermal issues for the optical transition radiation screen for the ELI-NP compton gamma source

A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with a laser beam in two interaction points. Electron beam spot size is measured with Optical Transition Radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the materia

Optical transition radiation screens: a numerical procedure to choose the most performing material

In the field of diagnostics applied to particle accelerators, and more specifically when it comes to linear electron accelerators, OTR screens represent one of the most widespread and used techniques for beam monitoring. These devices must be able to withstand the thermal stress that the several bunches induce by hitting the surface at high frequency, without compromising the optical performance following the possible induced deformations. This paper presents a complete methodology to predict the behaviour of the OTR screens – thermal, mechanical and optical – for a given beam and screen material with the aim to define guidelines for the optimal target material selection

Electromechanical analysis of SCDTL structures

The Side Coupled Drift Tube Linac (SCDTL) is a 3 GHz accelerating structure for proton therapy linac designed for TOP-IMPLART, an Intensity Modulated Proton Linear Ac- celerator for Radio-Therapy. The structure is made up of short DTL accelerating tanks for low current proton beams, coupled by side coupling cavities. The purpose of this pa- per is to report on the analysis of electromagnetic and the thermo-mechanical behavior for the SCDTL structure. The 3D electromagnetic analysis is used to derive the power dis- sipation on the structure; then one can infer the temperature distribution and deformation field in order to eventually eval- uate their feedback on the electromagnetic properties of the structure as, for instance, the cavity resonant frequency shift. Such a "multi-physics” analysis has been performed for dif- ferent supporting stem geometries in order to optimize the shunt impedance and the R/Q for SCDTL cavities

Thermal behavior of the optical transition radiation screens for the ELI-NP Compton Gamma source

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation profile monitors. In order to measure the beam properties along the train, the screens must sustain the thermal stress due to the energy deposited by the bunches; moreover, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the analytical studies as well as numerical simulations to investigate the thermal behavior of the screens impinged by the nominal bunch; the design and the performance of the optical detection line is discussed as well. In particular with the numerical simulations the behavior of the aluminum and silicon under thermal stress can be studied. The simulations allow us to see how the heat spreads on the OTR screen and frame, and what are their deformations during the heatin