Accelerator Science and Technology Seminar

Titel:

"Exploring Magnetrons as RF Sources for Accelerators and Nuclear Fusion"

Abstract:

A magnetron is a high-efficient (over 80% RF conversion efficiency) and compact high power microwave source, compared with other tubes, such as travelling wave tube (TWT) and klystrons. However, the magnetron is an oscillator in nature, in which the phase and amplitude of the output signal are not easy to be controlled.

We will introduce our design work in the magnetrons in S band and X band with a mega-Watt power level in a medical linear accelerator for generating gamma-rays as a single driving RF source. Also, the magnetrons have been explored to be used in a high energy particle accelerator as multiple driving RF sources. We have developed a novel technique to phase lock these magnetrons with a low power control signal.  On the other hand, we have been motivated to explore a millimetre wave (mmWave) magnetron as an alternative source for the plasma heating in nuclear fusion.

Titel:

"The TYRRHA-accelerator driven system and its accelerator"

Abstract:

After a brief motivation for an Accelerator Driven System (ADS), the requirements on the accelerator are derived.

It then details the MYRRHA design which is based on a 4 mA, 600 MeV CW superconducting proton linac. The construction of the first stage (called MINERVA) by the Belgium Nuclear Research Centre SCK CEN was approved in 2018. It consists of a 100 MeV superconducting RF linac as well as two independent target stations, one for radio-isotope research and production of radio-isotopes for medical purposes, the other one for fusion materials research. 

This contribution presents the main design choices and current status of the overall project parts (civil engineering, particle accelerator and target facilities.

Titel:

"Overview of permanent magnet projects at STFC Daresbury Laboratory"

Abstract:

In recent years the financial and environmental costs of constant electricity consumption have had an increasing effect on facility design and operation. Permanent magnets (PMs) provide an attractive solution to limit the required electrical power. Traditionally PMs produce a fixed field, attempts to alter this generally change field quality. STFC Daresbury Laboratory (UK) has championed the use of PMs to save energy in accelerators and, via the Zero-Power Tuneable Optics (ZEPTO) project, has demonstrated that tuneability of PMs is achievable in a manner suitable for accelerator requirements by moving PM blocks relative to fixed steel structures that define the field, allowing strength to be changed while suitable field homogeneity is maintained.

We present an overview of this project, including a prototype built for Diamond light source and one built for CLARA.   We also present a cautionary story of one of the potential drawbacks of permanent magnet systems, self demagnetization, discussing the design, construction, measurement and troubleshooting of a prototype hybrid Halbach quadrupole magnet. This magnet was significantly under-strength due to local demagnetization in the permanent magnet material. We discuss how this effect was uncovered, measured and reconstructed in simulations.