Electromagnetic and vacuum tests of the PTAK-RFQ module 0

TL;DR

This paper reports on the electromagnetic and vacuum testing of the PTAK-RFQ module 0, a prototype designed for proton acceleration at 800 MHz, including vacuum, RF, and tuning procedures to optimize its performance.

Contribution

It presents the design, fabrication, and detailed testing procedures of the first RFQ module, including a novel tuning algorithm optimized for the PTAK-RFQ.

Findings

Successful vacuum and RF tests of the prototype module

Effective tuning algorithm for field and frequency adjustment

Guidelines for final design and manufacturing processes

Abstract

A new Radio-frequency quadrupole (RFQ), which operates at 800 MHz high frequency and will enable to accelerate of the proton beam efficiently was designed at KAHVELab (Kandilli Detector, Accelerator and Instrumentation Laboratory) at Bo\u{g}azi\c{c}i University in \.Istanbul, Turkey. The so-called PTAK-RFQ, which consists of two modules with a total length of less than one meter will accelerate protons to 2 MeV at the Proton Testbeam at the Kandilli campus, known as the PTAK project. The prototype of the first module of the 800 MHz PTAK-RFQ (called the PTAK-RFQ module 0), which captures and bunches the proton beam injected from the ion source was fabricated by a local manufacturer from ordinary copper material. The PTAK-RFQ module 0 was subjected to various tests to ensure that its mechanics, pressure, field distribution, and frequency are operationally adjusted. The facilitating solutions emerging from the detailed testing of the PTAK-RFQ module 0 will ultimately guide all mechanical, vacuum, rf testing, final design, and manufacturing processes of the final PTAK-RFQ. The PTAK-RFQ module 0 was first subjected to vacuum tests and then to detailed vacuum leak tests. Subsequently, low-power rf measurements were performed for tuning of field and frequency. The tuning algorithm developed by CERN was optimized for 16 tuners and 6 test field points to be adjusted to the PTAK-RFQ module 0 to the desired field distribution. The tuning algorithm is based on a response matrix, whose inputs are created by bead-pull measurements of individual tuner movements. The tuning algorithm gives some predictions for corrective tuner movements to achieve desired field distribution. In the framework of all these RF tuning processes, the field distribution was tuned through the tuning algorithm and then the frequency was tuned manually.