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ESS RF Development at

Uppsala University

FREIA Division, Department of Physics and Astronomy

Uppsala University, Sweden

ESS: European Spallation Source

- High intensity neutron spallation source

- Construction starts in 2013

- First neutrons in 2019

- Long pulse faciliy

- 22 independent instruments for the study of

materials

- To be built in Lund

Schematic layout of the ESS accelerator

FREIA develops the RF power system prototype for

spoke resonator cavities, and do high power test of the

first prototype spoke cryo module.

The superconducting spoke resonator cavities accelerate the beam from the normal conducting section to the first

family of superconducting elliptical cavities

Cryomodules

Cavity/module

Frequency

Input Energy

Output Energy

ESS

36

2

352.21 MHz

50 MeV

200 MeV

FREIA

1

2

352.21 MHz

n.a.

n.a.

Spoke Cavity Section Spoke Cavity

Main Parameters

β

Length

Diameter

Thickness

Material

Operation Temperature

Operation Gradient

Epeak/Eacc

Bpeak/Eacc

RF Power to Beam

RF Power Input

RF Power from Source

RF Power for conditioning

0.50

687 mm

492 mm

4 mm

Niobium

2 K

8.5 MV/m

4.1

9 mT/(MV/m)

165 kW

245 kW

350 kW

400kW

ESS

D. Dancila, T. Ekelöf, K. Gajewski, V. Goryashko, L. Hermansson, M. Jacewicz, N. Johansson, T. Lofnes, M. Noor, R. Ruber, A. Rydberg, R. Santiago Kern, R. Wedberg, R. Yogi, V. Ziemann. Contact: rocio.santiago _kern@physics.uu.se

ESS Main Parameters:

Average Beam Power 5 MW

Pulse Repetition Rate 14 Hz

Proton Kinetic Energy 2.5 GeV

Beam Intensity 50 mA

Beam Pulse Length 2.86 ms

Bunch Frequency 352.21 MHz

Total Linac Length 583 m

Number of Target Stations 1

Number of Instruments 22 (44 max)

Annual Operating Period 5200 h

Source Proton Source

LEBT Low Energy Beam Transport

RFQ Radio-Frequency Quadrupole

MEBT Medium Energy Beam Transport

DTL Drift Tube Linac

Spokes Superconducting spoke cavities

Low-β Superconducting elliptical cavities

High-β Superconducting elliptical cavities

HEBT High Energy Beam Transport

Target Solid rotating tungsten Target

ESS RF Development at FREIA

Typical RF system layout