Phase stability and RF level distribution Requirements

Distribution type & MO location

Cable requirements ( phase versus T° stability & diameter)

Coupling value

T° regulation solution (heater, water, ...)

A PRDS 9m prototype is realized to test several T° regulation

and insulation solution. The tests are in progress.

50 100 150 2000

0.1

0.2

0.3

0.4

Lg 704.4, ( )

Lg 352.2, ( )

Lg 176.1, ( )

0.1

Lg

Christophe Joly*, Sylvain Berthelot, Beng-Yun Ky,Thomas Lester, Wladimir Sarlin, Jean-François Yaniche, Institut de Physique Nucléaire (UMR 8608)- CNRS/ IN2P3-Université Paris-Sud, Orsay, France

Holger Podlech

Johann Wolfgang Goethe Universitaet (Institute of Applied Physics) Frankfurt am Main, Germany

Dirk Vandeplassche

Centre d'études et de recherche Nucléaire (SCK*CEN), Mol, Belgium

LLRF for the RFQ prototype of the MYRRHA project LLRF17 Workshop / Barcelona, Spain /Oct 16-19, 2017

The goal of the European project called MYRTE (MYRRHA Research and Transmutation Endeavour), is to perform research to support the development of the MYRRHA facility

(Accelerator Driven System) with a main topic for the “Accelerator R&D for ADS/MYRRHA” Work Package (WP2): the Injector demonstration. Within this framework, a Low Level

Radio Frequency system for the Radio Frequency Quadrupole (RFQ) is developed by IPNO with an in-house standalone digital board including 2 FMC boards associated to a FPGA

linked to a processor ARM by PCIe. A Phase References generation system has been also realized and tested with the expected performance. This poster presents the project and

focuses to the hardware developments and to some results before the tests with the RFQ planned in May 2018.

This work is supported by the European Atomic

Energy Community’s (Euratom) H2020 Program me

under grant agreement n°662186186 (MYRTE

Project).

Conceptual layout of the MYRRHA Facility

Single SPOKE

352MHz

Double SPOKE

352MHz

Elliptical

704MHz

RFQ + CH

176MHz

Goals :

Build a hybrid reactor demonstrator for transmuting

radiotoxic waste, (ADS).

Radio Isotopes production to medicine

Fundamental research

Parameters of the MYRRHA project

Particles protons

Energy [MeV] 600

Frequency [MHz] 176.1 - 352.2 -704.4

Duty Factor [%] 100 (cw)

I [mA] 4

Beam power [MW] 2.4

MTBF [Hour] 250

Energy stability [%] ±1

Current stability [%] ±2

Reactor power th [MW] ≈60

keff ≈0.95

Fuel MOX

Target Eutectic Pb-Bi

RFQ

LLRF requirements

Amplitude stability [%] ±0.2 rms

Phase stability [Degree] ±0.2 rms

Frequency [MHz] 176.1

Bandwidth [kHz] > 84

RFQ Parameters

RF Structure 4.Rod

Frequency [MHz] 176.1

Beam current [mA] 5

Duty factor [%] 100

Eout [MeV] 1.5

Rp [kWm] 72

RF Power [kW] 113

Specific power [kW/m] 26.5

Voltage [kV] 44

Length [m] 4

Institut für Angewandte Physik

LINAC AG

RFQ assembly in progress at NTG facility

LLRF Requirements

ECR RFQ MEBT-1 CH-cavities MEBT-2 CH-cavities

Injector in

detail

(new design)

Due to beam dynamics studies of the global

accelerator and the RFQ characteristics, the

stabilities requirements will be better than

±0.3% rms and ±0.3° rms.

In this respect, a budget has been defined for

the complete LLRF system composed to the

Master oscillator (MO), the Phase Reference

Distribution System (PRDS) and the LLRF

Feedback loop system.

Then other parameters must be taken into

account as accelerator length, temperature

variation into the tunnel, etc.

LLRF FB System

Master Oscillator

REF Distribution

0.2 - -

0.1 0.1 0.1 Distribution by

subsystem

PRDS MO

LLRF FB loop system

Frequency

[MHz]

Jitter rms

[mDeg]

Jitter rms

[fs]

88.05 1.6 50

176.1 2.0 33

352.2 4.5 36

704.4 8.4 33

Results and measurement@704.4MHz

X2

X2 X4

X2

704.4 MHz

352.2 MHz

176.1 MHz88.05 MHz

PLL88.05 MHz

Splitter

X2

Multipliers

10 MHz REF for Local oscillator generation

Sampling clock

25kHz bandpass Filter

X N

10MHz Oscillator

Distribution amplifier

The LLRF system for the RFQ is based on a in-house

digital mother board called DALTON using a FPGA linked

to a processor ARM by PCIe, with two FMC slots. For HW and SW details, see P-38 “EPICS and VHDL developments

in the LLRF for MYRRHA Project's RFQ prototype” poster.

The regulation loop principle is based on the processing of

the RF cavity pick-up signal which is down-converted to an

10 MHz Intermediate Frequency (IF) signal. This IF signal

is then sampled by an ADC (FMC104-4DSP) to be

processed into the FPGA. The result is two I/Q control

signals which are converted by 2 DACs ( and used to

modulate the RF reference signal feeding the cavity, via a

vector modulator. The MO provides the Phase reference at

176.1MHz and the 10MHz need to produce the Local

oscillator (LO) signal, used by the down converter.

The Master Oscillator is realized using parts with Phase Noise

requirements very hard providing by ar Electronique (OCXO,

PLL) and Wenzel Associates (multipliers). A narrow bandpass

filter allows reducing the PLL noise as it is shown on the plot.

Conclusion

Fault tolerance Interlocks Bus

Auxiliaries ControlSystem

PLC

Master Oscillator

LLRF Feedback Loop System

PRDS

Frequency Tuning System

Fast Interlocks

System

Pf Pr Pt

Co

up

ler

10MHz

Beam axe

Vacuum , T°, cooling,

Cooling, defaults

SSPA

RF authorization

Personnel SafetySystem

RF authorization

MachineProtection

System

Gb-Eth (EPICS)

IOCTimingEVG

TimingEVR

Optical link

tun

er

RFQ

P A

Timing & Master Oscillator

FPGA

Digital board

DAC ADC

DAC

I Q

ADC

•Digital signal processing•Set points•Frequency tuning• Interlocks management• Communication EPICS•Feed Forward

DAC

REF Clock ( ADCs & DACs)Timing( Beam pulses, RF pulses,…)

10MHz

RF

REF RF RF-10MHz

Frequency Tuning System

Fault tolerance Interlocks Bus

Others Data(Forward power, Reflected Power,…)

RF switch

FrequencyDown converter

Personal Protection Safety Diagnostics

signals

Gb-Eth (EPICS)

Vectormodulator

RFQ

Machine Protection System

The LLRF prototype for the RFQ composed of the MO, PRDS and the FB loop will be tested in real condition in 2018 at Louvain-La-Neuve in Belgium where will be installed the injector until 6 MeV. The Master

Oscillator prototype gives very good phase noise results with a jitter inferior to 50fs for all references. The PRDS needs more tests to conclude about the T° regulation. The FB loop hardware and software (VHDL

and EPICS) are close to be operational and in parallel, we are studying a MTCA based version adapted to the MYRRHA reliability requirements. Thank you to the IAP, SCK*CEN and IPNO teams for their support.

ECR LEBT RFQ CH β 0.375

Single Spokeβ 0.705Elliptical

ECR LEBT RFQ CH

β 0.49 Double Spoke

176 MHz 352 MHz 704 MHz

SC sectioninjectors

60 cavities 18 cavities 72 cavities

Beam stop

Spallation target &

sub-critical core

LINAC

600 MeV

32 m 11 m 91 m 35 m 120m

15 cavities

Phase stability versus length for 0.1°C temperature variation using

a LCF38-50J FN( phase vs T° stability coef <6 ppm/°C, velocity :

87%)

10 Tc (K type) per 3 m section

positioned inside and outside

for a profile of temperature.

Insulated duct

heater

Cooling water

Coupler

T° sensors

REF cables

Contact : joly@ipno.in2p3.fr