Status JRA-SRF 2008 MS Project plan for 2008 JRA1_4Y_ mpp JRA1_4Y_ mpp LG_SC_07_08_ mpp Information about scientific progress in WP`s Status of deliverables High risk tasks

Insertion of a bare 9-Cell cavity into the DESY EB welding machine DESY prototype welding still ongoing, report under preparation

Figure 1: Present geometry and 5 mm thick NbTi end disk new geometry. Total end dishes stiffening is about the same (14 kN/mm). New geometry is simpler and would be cheaper. Deliverable 5 (task ), improved cavity design finished,

5 mm NbTi end dish. Stiffness is about 28 kN/mm for each end dish. 7 mm NbTi end dish. Stiffness is about 38 kN/mm Curved NbTi end dish. Stiffness is about 69 kN/mm Stresses (MPa) are calculated for 2 bar pressure difference.

Status seamless cavity by hydroforming Finished since some time –Waiting in cue with many TTF cavities for cold test, now ready for cold test

New task: Large grain / single crystal cavity

Single crystal cavity 1AC6 -Single crystal CBMM Nb with RRR 200; fabrication at Accel Co.; spinning of cups; BCP at Accel; EP at Henkel; HPR, assembly + tests at DESY => Gain of E acc : Additional material removal or EP-effect??? Q(E) - curves at 2K after BCP and EP + bake

The status of WP4.1 & WP4.2 Linear planar cathode arc coating Main problem of the past was a bad adhesion We have studied the adhesion of Nb films deposited upon polycrystalline copper substrates. – Those substrates were prepared applying the cleaning in citric acid (14 weight %) and various polishing treatments: machine polishing, and electropolishing We have found that the adhesion depends predominately on the chemical treatment before the deposition rather than on the mechanical polishing and resulted roughness of the substrates

Surface of samples after High pressure water cleaning

WP :Report on quality of HTc superconducting properties We investigated a quite the large set of deposition parameters without obtaining HTc films. The reason is that the Niobium nitride has different possible phases and only the "delta" cubic phase is superconducting with Tc up to 17K. Our guess was that using arc deposition, (due to the larger ions energy respect to sputtering) we could have a larger set of possible parameter for deposition Unfortunately this was not the case and the formation of the cubic phase in the case of arc deposition is at least as difficult as in the sputtering deposition. Since no improvement could be obtained with respect to sputtering we stopped research on HTc materials. A summary report should be ready in few weeks.

WP Transfer EP to industry EP at ACCEL

EP at Henkel

WP Automated EP Handbook is finished, detailed program code is protected because of private property rights Installation of automated EP at DESY under way

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Apparatus: key components + operation

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Operation of Nb cavity cleaning system for horizontal cleaning of (1-3)-cell cavities in stable operation iterative improvement of system operation and cleaning parameters during last four years => learning of bad cavity results, particle counting, etc. Cleaning procedure: - pre-assembly of pick-up flange to cavity - typical 3-4 cleaning runs per cavity (≈ 30 min each) => no cleaning of pick-up feedthrough during last dry-ice run => particles!!! - final run with nitrogen only (double speed) - assembly of antenna + frame; pumping + leak check

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Single cell Nb cavity results Results with actual cleaning parameters: => 3 of 5 tests show no fieldemission up to 35 MV/m; 2 tests with moderate FE

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Single cell cavity results (ctd.) Potential to remove HPR resistant field emitters ??

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Multi-cell cavities 2- and 3-cell cavity cleaning in preparation (until June 08) modification of apparatus for 9-cell (w/o He-tank!) stopped / delayed due to financial and man power problems => neither CARE nor DESY funding for necessary modifications (longer spray rod, extended IR-heater, extended base frame; app k€) available => man power occupied by construction and commissioning of new rf gun cleaning apparatus (urgent request by TTF/FLASH and preparation of European XFEL) Preference of new system for rf gun cleaning

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Copper rf gun cavity cleaning (ctd.) new vertical cleaning stand with modified movable nozzle

03/06/ dark current comparison of gun 3.1, gun 3.2 and gun 4.2 after dry-ice cleaning

WP 6.1 Deliverable report just finished. Comparative test of SQUID vs. nc Eddy current scanner ongoing. Decision needed for XFEL QA method.

WP 6.3 DC Field emission studies PhD publication is available 20-ArtiPhD2007.pdf This reference and three more publications cover all aspects of DC scanning; we need to select the right paper / papers for the two deliverables. I propose to take the PhD reference because it is the most general and complete one

WP8, UMI tuner deliverable report is just finished

ODR FLASH January 2008 Preliminary Analysis M. Castellano, E. Chiadroni (LNF-INFN), A. Cianchi (Roma2-INFN), K. Honkavaara, G. Kube (DESY-HH) WP 11.2 Beam Emittance Monitor

Experimental Setup 0.5 mm 1 mm An experiment based on the detection of Optical Diffraction Radiation has been set up at DESY FLASH Facility.

ODR nm filter - 1 bunches, 1 nC per bunch s exposure time - 5 Hz rep rate -  x =  m,  y = 85.5  m OTR image of the beam OTR angular distribution with 800 nm filter and polarizer nm filter - polarizer - 3 bunches, 1 nC per bunch s exposure time - 5 Hz rep rate With respect to last time, two big improvements have been done, i) a shield in front of the DR target to minimize the contribution of synchrotron radiation background and ii) a dedicated study of the beam optics to optimize the transport on the by-pass. Moreover the higher energy allowed to get promising results. Unfortunately a severe contribution of the dark current from the cathode was a big drawback, being from time to time a source of transition radiation. On the left, the OTR image of the beam at OTR57BYP station is shown. The transverse size is given in the table, together with the measurements parameters. On the right, the image of the OTR angular distribution and the its central profile are shown. The estimated energy is about 900 MeV.

High risk (RL3) activities in JRA-SRF This group contains tasks 4.1, 4.2 and 5.4. Vacuum arc coating is a well-known technology for thin film coating but has never been applied to SFR surfaces before… However, the prospect of getting higher accelerating gradients at lower RF losses has the tremendous potential to increase the efficiency. Dry ice cleaning (5.4) is used in semiconductor production but was never applied to SRF surfaces… The large potential of this method outweighs by far the high risk of failure … The results of research for a suitable power coupler conditioning procedure are inherently difficult to foresee. There may be no recipe for better conditioning than those which are known today…

Meaning / consequence of RL3 RL3: Significant downgrading of the objectives might be required. Alternatively, more R&D (more time and more money by more that 20%) would be required. For vacuum arc coating it could mean that coating experiments are concentrated on single cells rather than multicells For dry ice cleaning it also could mean to concentrate on single cells rather than multicells. But here the new and exciting benefit of dry ice cleaning of RF gun equipment more than outweighs the de- scoping of SRF cavity cleaning In any case, a detailed report is mandatory which describes the activities and explains possible reasons for the failure.

OTR (I) -  x =  m -  y = 87.5  m On the left, the OTR image of the beam at OTR57BYP station is shown. On the left side of the beam the dark current is also evident. The transverse size has been evaluated assuming the beam is Gaussian distributed, the rms size is given in the table. On the right, the image of the ODR angular distribution, obtained by sending the beam through a 0.5 mm slit aperture and looking at the image formed on the focal plane, is shown, together with its central profile. Even though a residual background is still present, clear side fringes are well distinguished. The nature of the asymmetry is still under exam.

Dark current ODR in the image plane ODR angular distribution with 800 nm filter and polarizer ODR (II) mm slit - 1 bunches, 1 nC per bunch s exposure time - 5 Hz rep rate nm filter - polarizer - 11 bunches, 1 nC per bunch s exposure time - 5 Hz rep rate The image on the left shows the beam through the center of the 0.5 mm slit aperture in the image plane. In this condition, the optical system is focused on the ODR source itself. On the right, the ODR angular distribution and its central profile are shown. Even more side fringes are clear in this measurement.

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Drill hole cleaning with CO 2 recent development at Fraunhofer IPA: Contaminated drill hole (swarf & oil) CO 2 injector Procedure of drill hole cleaning Test drill hole for contamination control

Status Mar 08 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Open topics + ideas - Further optimisation of cleaning parameters (N 2 -pressure,..): e.g. reduced CO 2 -capillary size=> reduce consumption of CO 2 =>reduce/avoid moisture condensation =>avoid heating ?? => ensure cleaning effect !! e.g. cleaning speed: => topics as above => expert’s report of Fraunhofer IPA reasonable, but no funding available - What is the “better” nozzle head: One movable nozzle vs. two fixed nozzles? (angle of nozzles?) - If we must avoid moisture condensation: heating of cavity vs. inert gas atmosphere ??