Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
The planned beam tests at ANKA with a superconductive undulator and ideas for future developments
S. Chouhan, R. Rossmanith, S. Strohmer Institute for Synchrotron Radiation, Research Center Karlsruhe, Germany D. Dölling, A. Geisler, A. Hobl, S. Kubsky ACCEL Instruments Gmbh, Bergisch Gladbach, Germany
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
History: A Karlsruhe-Mainz collaboration tested a sc undulator successfully with beam in Mainz
One half of the undulator Measured vertical spectrum 855 MeV (single photon) 100 µA cw 3.8 mm period length 100 periods 2 mm gap
Can this concept be expanded to a storage ring device: phase error? Current 200 mA? storage ring vacuum compatible? insensitive to synchrotron light from nearby bendings? insensitive to injection? and? TEST AT ANKA
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
Collaboration with ACCEL Instruments GmbH and National University of Singapore (Prof. Moser)
ANKA: 2.5 GeV Undulator: 14 mm period length 200 mA 100 periods Injection at 0.5 GeV in steps variable gap: Bunchlength 10-12 mm open (25 mm) 5, 8, 12 and 16 mm (Cold bore)
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
Three experimental steps:
1.) 10 period, 14 mm period length prototype to test phase error and industrial production techniques (succesfully finished)
2.) Singapore undulator, 50 periods, 14 mm period length, low beam current (close to finish)
3.) ANKA undulator, 100 periods (under construction) (Talk of Stefan Kubsky)
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
Beam- Wall Heating
ANKA experiment will use a Cu-foil (see talk of S. Strohmer)
For future undulators: sc – shield?
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
Example: Resistive wall High temperature: R defined by heating in Cu lattice vibrations and imperfections
Electrons in wall move with beam
e-
R defined by Resistivity [>.m] Low temperature: imperfections only Residual resistivity ratio RRR
room/ 4K > 60 for Cu e- ( depends on material quality) Surface resistance R #()1/2
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
Heating depends on: current bunch length gap width Estimate < 100 - 200 mW/m for ANKA (see talk of S. Strohmer this workshop)
Summary; fine for the ANKA test, but is this the ultimate solution ?
R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft
Required is a sc foil instead of a Cu-foil
Phase I superconductor Phase II superconductor
Magnetic field lines
superconducting
T>TC T R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft normal TC [K] BC2[T] BC2 Shubnikov NbTi 10.2 12 phase Nb3Sn 18.3 30 BC1 YBa2Cu3O6.9 92 100 Meissner state Other HTSC ≤ 100 ≤ 1000 TC Ultimate solution: inner shield is HTSC layer (but still problems to be solved) Electrons in wall move with beam a.) how near sc layer to surface? b.) Magneto-resistance effects? c.) HF-behaviour (anomalous effect) Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Compatibility with storage ring vacuum system thin foil spacer Double vacuum system: insulation vacuum beam vacuum Insulation vacuum 4 K Beam vacuum 60 K Remains operational, even when one vacuum is broken Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Installation in ANKA: Hor. And vertical scraper valve R Rossmanith Grenoble June 2003 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Summary: 1.) Preparation for beam test In addition thougths about 2.) Electric phase shimming 3.) SC phase II shield against resistive wall heating