UK Neutrino Factory WP2 - Proton Driver Front End Progress Report

1. UK Neutrino Factory WP2 - Proton Driver Front End Progress Report Alan Letchford UKNF Meeting, CR12, R68, RAL. 4th May 2005

2. H- Ion Source ProgressD Faircloth et al, RAL • Separate Penning field • Longer discharge pulse • Increased output beam current

3. 1. Separate Penning Field

4. Variable Penning Field • Allows easier start-up of source • Allows the source to operate in “non-standard” conditions • Improves arc stability • Allows better control of discharge noise • High Penning Field slightly increase beam current

5. 2. Longer Discharge Pulse The discharge length has been increased by improving cooling. 1.75 msec achieved so far.

6. 70mA beam current 3. Increased beam current Increasing the beam aperture size gives H- currents up to 70 mA.

7. Increased aperture has little effect on beam emittance: 0.6 mm aperture width 0.8 mm aperture width

8. LEBT progress J Back, Warwick, J Pozimski, Imperial/RAL • 3 solenoid magnetic LEBT adopted as baseline design. • KV envelope code ENVELPC converted to C++ for initial optimisation studies: • Sufficient drift space for pumping and diagnostics • ‘Sensible’ solenoids (l < 4 × rbore)of equal length • Field ≤ 0.6 T • Effective currents up to 10% of actual current due to partial neutralisation

10. RFQ Progress A Kurup, Imperial, A Letchford, RAL • 324 MHz has been ‘officially’ adopted as the FETS frequency. • Choice dictated by ready availability of Toshiba E3740A 3MW pulsed klystron (J-PARC).

11. Initial investigations of a beam dynamics design at 324 MHz are encouraging. • A 3 MeV design giving 95% beam transmission in a 4 m long structure with only 80 kV electrode voltage. • The low voltage design means power dissipation is within the capability of the preferred 4-rod type of RFQ. • Resurection of the ESS 280 MHz resonator design forms the basis for initial electro-magnetic studies using MAFIA. • Integration of mechanical CAD, electromagnetic and thermodynamic codes to produce an integrated design procedure.

12. Chopper Progress M Clarke-Gayther, RAL, G Bellodi, F Gerigk, Astec The phase 2 fast pulser now meets the spec. for rise time, fall time, pulse duration …

13. … and pulse droop Phase 1 Phase 2

14. A complete revision of the FETS chopper line optics has resulted in significant performance gains: • Deflection of fast & slow chopper is optically increased by defocusing quadrupoles. • More efficient deflection allows shifting the MEBT energy from 2.5 to 3.0 MeV, while using 10% less voltage than in the ESS scheme. • Chopped beam from fast & slow chopper is collected in 2 dedicated beam dumps, designed to take full beam power (no need for 2 identical chopper sections). • Now only 30% of original plate voltage for the slow chopper is required (6 kV → 2 kV),  faster rise time for slow chopper. • Larger apertures for all elements.

15. Original chopper line Revised chopper line

16. Diagnostics Progress J Pozimski, Imperial/RAL, P Savage, Imperial A full suite of diagnostics is being to maximise the experimental capabilities of the FETS. In addition to the usual beam current and emittance measurements, more advanced techniques such as non-destructive laser/optical measurements and residual gas ion spectroscopy are being investigated.

17. Hugh Rojanski type electrostatic spectrometer Engineering designs of an HR type electrostatic spectro-meter for the FETS HR type spectrometer built at IAP Frankfurt

18. Conclusions • Significant progress is being made on the FETS design work with contributions from RAL/ISIS, Astec, Warwick and Imperial. • The design is maturing with most of the design issues having been settled. • The FETS team is working well with considerable knowledge transfer taking place between the more established and newer members of the team.