DTL design Laboratori Nazionali di Legnaro Italy A

DTL design Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012

Group involved • The participation to IFMIF-EVEDA project (RFQ realization) is based on four INFN sites (LNL, Padova, Torino, Bologna) with competences in accelerator physiscs, RF, mechanical engineering, computer controls, vacuum, brazing. . . • Almost all of these competences (+Naples) will be gradually involved in ESS DTL, at present – – – – AP (coordination) M. Comunian (beam dynamics) F. Grespan (RF) R. De Prisco (RF) P. Mereu (Mechanical design, Torino) V. Vaccaro (RF stabilization, Napoli) C. Roncolato (vacuum) E. Fagotti (cooling system and acc. Phys. ) Laboratori Nazionali di Legnaro (Italy) IFMIF EVEDA RFQ organization In INFN LNL group A. Pisent ESS LNL 2012

Collaboration with CERN linac 4 • Collaboration on DTL since 2006, in design (F. Grespan 1 year visit at CERN for PHD thesis on DTL stabilization) • participation of INFN to the construction of DTL prototype. • INFN is in charge of the construction of movable tuners of linac 4. • 13 Sept 2011 we had a miniworkshop on main aspects of DTL realization. https: //indico. cern. ch/conference. Display. py? conf. Id=152766 • We are finalizing the paper work for full access to Catia drawings (starting point for mechanics). Laboratori Nazionali di Legnaro (Italy)

Physics design high-lights • Defined the DTL design for 50 m. A, 4 tanks, 16 modules. • In July we had a very fruitful visit by Mohammad and we (or better Mohamad, Michele, Francesco and Renato) arrived to a new beam dynamics that fulfills all the main requirements: 1. phase advance/meter matching at high energy 2. agreed evaluation of shunt impedance, surface field, stabilization capability 3 increased transverse acceptance (bore aperture) and longitudinal acceptance. 4. RF dissipation power density and module length compatible with CERN mechanical design. • Main differences of ESS design with respect to the Linac 4 design (behoind the energy range): – – – Use of FODO lattice instead of FFDD. Stronger PMQ in the first tank. Use of steerers and diagnostics (BPM) inside DT. Ramped Field E 0. Higher energy for the first inter tank transition. Shorter intertank space: 1 bl instead of 2 bl. • All these changes are in the direction of a smoother lattice. Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012

Main design parameters Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012

Answers to referees (1/2) • Jim Stovall and Suitbert. Ramberger • As Jim points out, it is essential that the DTL fits with the overall machine and that the transition energy to the Spokes is justified. Matching of phase advance per meter and real estate gradient achieved at approximately 78 Me. V. What are the design constraints from the RF system? Is there an rf issue associated with the chopping, e. g will the cavity field respond to the gap in beam loading? Details not studied but the Ql is about 40 000, so we are quite insensitive to beam loading variation on short time • One also needs to address the constraints and goals for the DTL design itself. Just to mention few: – Within the overall beam dynamics requirements, should it be optimized towards lower operating costs (fewer klystron) or towards lower structure length and thus manufacturing costs? - How does the current design fit with this goal? Current design is optimum towards operating costs, and quite good for manufacturing cost (respect to the 5 tank option 32/27 m structure, 16/13 modules, but 8/10 couplers (in our cost perimeter), 8/10 RF systems. Moreover reduced design effort since accelerating field below 3. 2 MV/m and 2 m module length as for CERN design). Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012

Answers to referees (2/2) – The tank segment length turns out to be an important ingredient in that game as for mechanical reasons in the Linac 4 design, the first interface to the next segment should be placed above ~7 Me. V. - One needs to foresee machining, heat treatment, metrology verifications, copper plating, assembly, and maintenance for the chosen segment length. • We are compliant with these two conditions (Lmodule. MAX=2. 1 m, Wout module 1. 1=7 Me. V) – The choice of material for the tanks needs to be seen in the larger context of the installation at the ESS. Has this been discussed and decided based on the consequences? • Discussion not started yet; thermo-mechanics possible for both iron and stainless steel. – Using EMQs and diagnostics in drift tubes is an issue of reliability and requires some effort. What is foreseen for prototyping in terms of resources and schedule? How does this fit with the overall schedule? • Design and prototype of the drift tube are foreseen for end 2013, we can possibly test it in the tank prototype at CERN. It is not on the critical path, SNS case suggests feasibility, the positioning tolerances are looser than for PMQ DTs Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012

Elements part of DTL WP (boundaries) LPRF Control system HPRF RF network RF window Local Control system Steerer PS Alignment refs DTL INFN Vacuum pumps support Water cooling skid Heat exchanger General water distribution Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012 Beam port flange MEBT RF coupler RF pick ups Spoke section

Conclusions • Plan for prototyping • Mechanical design based on tank design developed at CERN (accurate positioning and fixing of tube position, metallic gaskets). • We plan to develop DT for steerers or diagnostics, with electrical connections out of the stem. • Such DT will be tested at high power in the DTL prototype (developed by CERN and INFN) • PM (with rectangular or trapezoidal components? ) should be prototyped. We have a design with rectangular components reaching 70 T/m. • A first Catia model of the DTL linac has been produced • Construction and tests perspective – Tank and DT can be built in local industry (see again prototype). Brazing and e-beam welding are possible in 70 km distance. – INFN (LNL, Torino and Padova) has the structures for high precision milling, vacuum brazing, CMM, EDM, RF measurements, laser tracking, assembly of the tank and low power tests. – We are looking for an industrial partner for copper electro-plating, the design is compatible with GSI and CERN galvanic. Full scale prototyping of a tank would be beneficial. – Moreover a power system could be installed in LNL for high power tests and conditioning of couplers and tanks (dedicated space and RF source under discussion with INFN management). Laboratori Nazionali di Legnaro (Italy) A. Pisent ESS LNL 2012

Beam diagnostics To be set -cavity phase (low current, 3 BPM for TOF and/or FC with degrader) -steereres and injection line setting(BPMs in the line and transmission) -wire scanner to check beam dimension (and extrapolate emittance) - Halo with Beam loss monitors Benjamin Cheymol Laboratori Nazionali di Legnaro (Italy) Mechanical integration of «empty» DTs And intertank can start only now A. Pisent ESS LNL 2012