# Presentation: 686462

## Feasibility Study of a

**Feasibility Study of a**
**Combined Neutron Centre**
**for European Research**
**and Technology**
**A. Mosnier & E. Klein**
**for the CONCERT team**
- a series of applications could benefit from the outstanding performance of the forthcoming generation of high power proton accelerators (HPPAs)
-  Condensed matter studies by neutron scattering
-  Nuclear physics - study of Rare Ion Beams (RIBs)
-  Accelerator Driven Transmutation (ADT) of long-lived radioactive waste
-  Technological Irradiation Tool (TIT) testing of materials
-  Particle physics (muon colliders and neutrino factories)
- expected increase in incident power reflected accordingly
- in the fluxes of secondary beams

**COmbined Neutron Center for European Research and Technology**

- Proton in the 1 GeV range

- Neutrons
- produced
- by spallation

## Major expectations for experiments

- Condensed matter
-  ~ 10 - 100  times higher flux [when all neutrons in the pulse
-  are used (Time Of Flight/energy correlation)], than produced
-  by the best research reactors
- Radioactive beams
-  ~ 10 15 fission products per second
-  Gain of up to 10 4 in flux (or equivalent exoticity)
-  in comparison with projects under construction
- Accelerator Driven Transmutation
- 100 MWth for a subcritical system (keff~0.95) with a 5 MW HPPA beam
- Irradiation tool
-  ~ 10 15 n cm-2 s-1 and some ten displacements per atom (dpa) per year
- Neutrinos
-  ~ 10 21 neutrinos (of all types) per year, orders of magnitude
-  higher than today SPS production.

## 	many similarities in requirements for HPPA drivers

- User	 Beam Power	 Energy	 Current
- Condensed matter	 5 MW	1.3 GeV	 3.75 mA	ESS project
- Radioactive Ions				EURISOL project
-    from protons	~ 200 kW	> 200 MeV	~ 1 mA
-    from neutrons	~ 5 MW	~ 1 GeV	~ 5 mA
- Transmutation
-    100 MWth demo	~ 5 MW	~ 600 MeV	~ 10 mA
-    Industrial system	~ 50 MW 	~ 1 GeV	~ 50 mA
- Irradiation tool	> 10 MW	~ 1 GeV	10 mA	SPALLAX
- Muons - Neutrinos	4 MW	2 GeV	2 mA	SPL (CERN)

- 	many similarities in requirements for HPPA drivers
**	****to serve pulses at 50 Hz to all applications**
- 	The power would then be adjusted by adapting the individual pulse length
- 	This will result in a very robust operation of the driver since :
- 	peak current, space charge, focusing and RF tuning will remain constant

## Typical pulse sequence

**Typical pulse sequence**
- (for a 1.334 GeV linac and 107 mA peak current)

-  A series of 50 Hz pulses distributed over the 20 ms period
-  each pulse duration adjusted to satisfy the desired power of a given application
-  H+ for all current pulses except for short pulse of spallation neutron source :    chopped H- beams for a proper injection into a compressor ring
-  bunch charge Cst for all pulses (to keep space charge Cst) chopped H- ~ 70% H+
-  total beam power of 25 MW with a duty cycle of 25%
-  interval between successive pulses ~ 100 s   to operate fast switching magnets without beam loss

## Architecture of the Linac

**Architecture of the Linac**

- 95 keV

- 5 MeV

- 10 MeV

- 85 MeV

- 185 MeV

- Reliability, availabiliy and flexibility
- Robust and based on well-proven technologies
- Major concern : minimisation of beam losses (< 1W/m for hands-on maintenance)
-  careful beam-dynamics design (to minimize the risk of halo formation & emittance growth)

## 0

- 90 MeV

**185 MeV **

**SDTL**

**CCL**

- 100mA

**0**

**38 m**

**54 m**

**186 m**

**176 MHz**

- Chopperline

- 352 MHz

**RFQ 1**

**RFQ 2**

**DTL 1**

**H****-**

**352 MHz**

**23 MeV**

**RFQ 3**

**DTL 2**

**H****+**

- 95 keV

- 352 MHz

- 104mA

**Low Energy Linac scheme**

- 55mA

**RFQ 1**

**RFQ 2**

**DTL 1**

**H****-**

- 55mA

- Funneling

- 50 keV

- 2 MeV

**5 MeV**

- 23 MeV

- 5 MeV

- 352 MHz

- 352 MHz

- 704 MHz

- Poster RPPH022 Thursday 21 afternoon (R. Ferdinand et al)

## Principle of the funnel line

- Deflection by a special cavity (Y. Senichev)

- deflecting field
- multicell cavity
- easy cooling

- Poster FPAH098 Friday 22 morning(N. Pichoff et al)

- close to the cavity peak field (limited at 1.2 Kilpatrick to avoid spark down)
- allows for reaching the desired 10° deflection angle without using dipole magnets
- high shunt impedance and only 6% duty-cycle

## Transition energy between

- 352 MHz DTL and
- 704 MHz CCL structures
- determined by the crossing
- of the shunt-impedances

- Cost variation of the CCL structureas a function of the field
- Broad minimum around 3.5 MV/m

## High Energy Linac scheme

-  Transition energy between NC & SC fixed at 185 MeV
-     (below 200 MeV, energy gain per real-estate meter for SC < 2 MeV/m and
-       design of SC cavities for b < 0.6 complicated by stiffness & microphonics issues
-  for the present design : 50 mT peak magnetic field selected
-     (conservative factor of 2 lower than the surface field aimed at TESLA project)
-  entire SRF linac inferred from an optimisation of the linac length
-     (in terms of number of cells per cavity, number of cavities per module, etc)
-  3 fundamental constraints :
-     - max Eacc below a prescribed value, which depends on the cavity “beta”
-     - longitudinal phase advance per cell below 90° for stability reasons
-     - beam power per cavity below the input coupler capability

- Poster RPPH021 Thursday 21 afternoon(A. Mosnier et al)

## empirical law for the setting of gradientin proton linac

- as a function of the cavity “beta”
- expected gradients for two valuesof peak magnetic field,
- + data of the cavities designedby the French-Italian collaborationand for the SNS Linac,
- with peak surface fields of 50 mTand 27.5 MV/m

- Energy gain per cavityas a function of beam energy(Phis = -25°)
- Assuming 2 couplers per cavity=> maximum beam power     of 1 MW per cavity

## RF system

-  the "one klystron per cavity" scheme has been selected :    each cavity has its own feedback/feedforward control system and provides
-     the best RF stability, the simplest operation procedure, the greatest flexibility
-  2 klystron types (950 kW and 1400 kW saturation power) because of
-     the large variation of the RF power needed from the low-E end to the high-E end
-  power supplies made of series-connected modules
-     with IGBT switches operating in pulse width modulation (PWM) mode
-     (combination of long pulses : 5 ms pulse length capability & fast switching times
-      with high repetition rates  : 25% maximum duty cycle)

## Multiparticles simulations ...

- In the error free machine first with a matched input beam
- 	to check the overall architecture as well as beam matching
- Second with a mismatched input beam
- 	to test the robustness of the linac design
- End-to-end simulations w/o errors showed excellent beam qualities
- without significant beam tails (only 10-3 particles outside 3 times the rms size)

- Poster RPAH013 Thursday 21 morning(N. Pichoff et al)

## Conclusions

-  The idea of a multi-application facility is technically achievable with today's technology and the architecture of a robust accelerator of the 25 MW class has been designed
-  Following this feasability study :
-  	- most possible scenario = ESS-like facility to start with(short + long pulses version) for condensed matter study
- 	- upgrade & flexibility integrated in the design will allow for accomodating other applications at a later stage

## A single HPPA as a driverof a multipurpose facility

- A single HPPA as a driverof a multipurpose facility

- Test possibilities for a muon/neutrino facility
- 4 MW, 0.8 ms pulse

- Spallation
-   neutron source
-        5 MW, 1 ms pulse

- R&D associated with
- Transmutation
- Hybrid demonstrator
- 5 MW, 1 ms pulse

- Irradiation Tool
- 10 MW, 2 ms pulse

- Rare Isotope Beams
- 1 MW 0.2 ms pulse

- Fixed peak current
- Power adjusted by pulse width

- 1.3 GeV Linear Accelerator, 25 MW

- H+ source

- H- source