HTS coatings for impedance reduction of beaminduced RF

HTS coatings for impedance reduction of beaminduced RF image currents in the FCC-hh Sergio Calatroni HTS coatings for the FCC-hh 1

Synchrotron radiation/beam screen High synchrotron radiation load (SR) of protons @ 50 Te. V: ~30 W/m/beam (@16 T) à 5 MW total in arcs (LHC <0. 2 W/m) New type of ante-chamber LHC beam screen absorption of synchrotron radiation - avoids photo-electrons, helps vacuum - Photon distribution Heat transport R. Kersevan, C. Garion, L. Tavian, et al. Sergio Calatroni HTS coatings for the FCC-hh 2

contributions: beam screen (BS) & cold bore (BS heat radiation) Cryo power for cooling of SR heat Overall optimisation of cryo-power, vacuum and impedance Termperature ranges: <20, 40 K-60 K, 100 K-120 K Ph. Lebrun L. Tavian V. Baglin 300 MW 200 MW 100 MW Multi-bunch instability growth time: 25 turns 9 turns (DQ=0. 5) Sergio Calatroni HTS coatings for the FCC-hh 3

HTS films requirements for beam screen Bunches of 1011 protons, 8 cm long Frequency spectrum for various bunch shapes Beam instantaneous image current Beam screen of 30 mm diameter. Assuming a film thickness / skin depth of 1 µm the HTS material should have a critical current density 2 Jc of about 25 k. A/cm (2. 5 x 108 A/m 2) at 50 K and 16 T Sergio Calatroni HTS coatings for the FCC-hh 4

Surface resistance: general definition Sergio Calatroni HTS coatings for the FCC-hh 7

Expected performance • • Using YBCO as model, 77 K RBCS and Rres, at zero Hrf and zero Bext HTS can have surface resistance lower than Cu at T< 77 K and 0 T f < 10 GHz M. Hein, “High-Temperature Superconductor Thin Films at Microwave Frequencies”, Springer Sergio Calatroni HTS coatings for the FCC-hh 8

Surface resistance: general definition Flux flow depends on pinning strength and frequency Flux flow regime Ratio of SC/NC surfaces No flux flow Gittleman and Rosenblum: Journal of Applied Physics 39, 2617 (1968 ) Sergio Calatroni HTS coatings for the FCC-hh 9

Expected performance: nonzero Hrf and Bext 30 K 4 x YBCO films at 8 GHz (coeavporated) Sergio Calatroni J. R. Powell, A. Porch, A. P. Kharel, M. J. Lancaster, R. G. Humphreys, F. Wellhöfer, and C. E. Gough: Journal of Applied Physics 86, 2137 (1999) HTS coatings for the FCC-hh 11

Expected performance: nonzero Hrf and Bext 77 K 4. 2 K THEVA films at 28. 2 GHz J. Krupka, J. Judek, C. Jastrzębski, T. Ciuk, J. Wosik, and M. Zdrojek: Applied Physics Letters 104, 102603 (2014) Sergio Calatroni HTS coatings for the FCC-hh 12

Expected performance: nonzero Hrf and Bext T. Honma, S. Sato, K. Sato, M. Watanabe, A. Saito, K. Koike, H. Kato, S. Ohshima, Physica C 484 (2013) 46– 48 YBCO co-evaporated on Mg. O What is the right frequency and field scaling? To be validated experimentally Sergio Calatroni HTS coatings for the FCC-hh 13

HTS options • Bi. SCCO: • Strong anisotropy reduces Jc, Hc at high temperatures Ø Not suitable for the application • YBCO: • • Proven performance Challenging to coat inside beam screens Ø Collaboration proposal by ICMAB-CSIC, IFAE and CELLS (ALBA) • Tl-1223 (Tl-Ba 2 Cu 3 O 10): • • Promising performance, opens up >100 K temperature window Scalable coating -> focussed R&D for optimised deposition technology, planar epitaxy onto Ag Ø Collaboration with CNR-SPIN and TU-Wien, approved by FC Sergio Calatroni HTS coatings for the FCC-hh 14

Materials D. Larbalestier et al. , Nature 414 (2001) 368 Data from: A. A. Khurram, Nawazish A. Khan, J. Electromagnetic Analysis & Applications, 2010, 2: 63 -74 Sergio Calatroni HTS coatings for the FCC-hh 15

What is a Coated Conductors (CC) CC is a long length (km) epitaxial YBCO films on a flexible metallic substrate capable of carrying large currents Present commercial values are 200 A/cm-width @77 K and 750 A/cm-w @4. 2 K for 20 T. Ag protection (0. 5 -1 m) YBa 2 Cu 3 O 7 (1 -2 m) Buffers (0. 5 -1 m) (oxides non-conductive) YBCO Metallic substrate (50 -100 m) - Proven technology and performance (Stainless steel or hastealloy) - Extremely high irreversibility field - Grain-boundary issues solved by CC technology - Critical current anisotropy much reduced by nanocomposites - Many device prototypes achieved with demonstrated mechanical and handling performance

Comparison: Y-123, Bi-2223, Tl-1223 Sergio Calatroni HTS coatings for the FCC-hh 18

Sergio Calatroni HTS coatings for the FCC-hh 19

Collaborative proposal for FCC Beam Screens based on Coated Conductors Teresa Puig Institut de Ciència de Materials de Barcelona, CSIC, 08193 Bellaterra, Spain Francis Pérez ALBA Sincrotró, Parc Alba, 08290 Cerdanyola, Barcelona

Collaborative proposal 1. - Use wide CC and solder a single piece on the steel plate before deformation CC 2. - Shape the ensemble CC Schematic drawing not at scale 3. - Ensemble the two site of the chamber The two inner pieces of the chamber can be covered by the CC before assembling Simulations of 1 m YBCO layer have shown the benefit of superconducting surface impedance reduction at RF S. Calatroni, IEEETrans. Suprcond. (submit. ) CC CC

Sergio Calatroni HTS coatings for the FCC-hh 22

Open questions • RF characterization is needed in order to validate materials, deposition process and scaling to tubes. • Ideally, RF characterization should be done on • • Small size samples Finished beam-screen sized “tubes” • The challenge is to perform RF characterization up to 16 T and in the range 4. 5 K – 120 K (or larger) • Expertise on RF devices available within the HTS-RF community Sergio Calatroni HTS coatings for the FCC-hh 23

Outlook • Strong motivation for HTS coatings for FCC beam screens, with potential of drastically reducing beam impedance. • YBCO: • • Tl-1223: • • • Proven performance Challenging to coat inside beam screens Proposal to study assembly technology for tapes promising performance, opens up >100 K temperature window scalable coating -> focussed R&D Coating properties need extensive experimental validation, for any specific coating process. Sergio Calatroni HTS coatings for the FCC-hh 24