Energy Deposition due to Secondary Particles in The Helical Undulator Wall at ILC-250GeV

TL;DR

This paper investigates the power deposition caused by secondary particles in the vacuum of a helical undulator at the ILC-250GeV, proposing a mask model to mitigate heat loads for efficient positron production.

Contribution

It provides a detailed analysis of secondary particle-induced power deposition and introduces a mask model for the undulator vacuum in the ILC-250GeV.

Findings

Power deposition levels are quantified for the undulator vacuum.

A mask model is proposed to reduce power deposition.

Results inform the design of photon masks to prevent overheating.

Abstract

In the future, International Linear Collider (ILC), a helical undulator based polarized positron source is expected to be chosen. A high energy electron beam passes through a superconducting helical undulator in order to create circularly polarized photons which will be directed to a conversion target, the result of which, will be electron-positron pairs. The resulting positron beam is longitudinally polarized. In order to produce the required number of positrons in ILC250 the full undulator length is needed. Since the photons are created with an opening angle and traveling through a 320 m long undulator, it is expected that the superconducting undulator vacuum will be hit by the photons. Photon masks are needed to be inserted in the undulator line to keep the power deposition in the vacuum below the acceptable limit which is 1W/m. A detailed study of the power deposition in the vacuum and masks is needed in order to design the photon masks. This paper describes the power deposition in the undulator vacuum due to secondary particles assuming an ideal undulator. In addition, the mask model is proposed.