INFN Milano LASA News on Cathode Development

Transcription

1 INFN Milano LASA News on Cathode Development PITZ Collaboration Meeting December 7 8, 2010 L. Monaco and D. Sertore, INFN Milano LASA Presented dby D. Sertore 1

2 Outline LASA preparation system status t Work done and maintenance Analysis A l i of occurred problems Carrier movements, cathode movements, etc. Diagnostic after usage The RF contact spring Results with the new diagnostic High reproducibility and better parameter control Status of the new cathode systems FNAL/LBNL 2

3 Production at LASA: Work done Since the last PITZ collaboration Meeting (June 2010) 1 box (long1) for PITZ with: 1 standard Cs 2 Te (94.2, 10nm of Te) 1 standard Cs 2 Te with Cs excess (110.2, 10nm of Te) 1 Mo (127.2) 1 Mo (104.3) 1 box (long3) for FLASH with: 1 standard Cs 2 Te (cathode 109.2, 10 nm of Te) 1 standard Cs 2 Te (cathode 114.2, 10 nm of Te) 1 standard Cs 2 Te (cathode 91.2, 10 nm of Te) 1 standard Cs 2 Te (cathode 77.3, 10 nm of Te) 1 box (short2) for PITZ under preparation: 4 Mo plugs have been loaded Baking g done; this week the deposition will start Standard Cs 2 Te will be prepared (up to 4, depending on the Cs sources status) 3

4 Production at LASA: work for the next maintenance (beginning gof 11) UHV valve replacement: The UHV valve leak in the pneumatic circuit has been repaired. We have also a small vacuum leak (10 10 mbar range) Will be substituted during the next maintenance of the system (usingthevalve received from DESY) New masking system: We have modified the masking system to limit the deformation occurring after baking of the system It will be mounted during the next maintenance of the chamber Cs sources : Cssources sources are almost empty. Csavailable for 3 4 cathodes They will be changed during maintenance The new masking system 4

5 Occurred problems: carrier movements Carrier movements (long1) Carrier in box long1 at PITZ don t move correctly. Investigation will be done at LASA (when the box will come back) PITZ exchange chamber Drawing of Long transport box 5

6 Occurred problems: cathode movements Cathode movements (short2) The carrier has been disassembled and all components (sliding blocks, ball bearings, etc.) have been carefully checked All tolerances are ok One plunger was not in the correct position the carrier has been inserted in the box and it is now ready for the production Not proper p plunger position Signs on the cathode side 6

7 Diagnostic after usage: RF contact spring RF contact spring damages In cathode many damages due to the RF contact spring have been observed Burns Spring convolution The RF contact spring damages have been observed only on the cathodes used in the DESY Gun4.2 (60.2, 123.2, 95.3) Cathode and 115.2used only in DESY Gun4.1 have no damages Burns This cathode was used for: 30 days of operation in DESY Gun4.2 (now installed at FLASH) for some days in the DESY Gun4.1 (now in operation at PITZ) The spring convolution signs 7

8 Production at LASA: the new diagnostic Multi wavelengths diagnostic and the improvement of film reproducibility Since two years we applied the multi wavelengths diagnostic i during the film deposition i obtaining: i Good reproducibility of the film characteristics Less sources consumptions bins QE (%) = / Moreover: 14 The analysis of the E g +E a can give a new tool to follow the energy threshold formation in view of a better 8 control of the final thermal emittance of the film bins QE (%) = 8.6 +/- 2.7 Proposal: Production of ad hoc film Pollution of standard dcs 2 Te Production of different films (KCsTe, etc.) QE (%) 8

9 New cathode systems: FNAL New Muon Lab Photocathode Preparation System System setup finished Bake out in progress (already 10 days) Ready for cathode production before Christmas Photocathode th Transfer System System setup ready Test dummy gun with spring successful Next Plan End January/Beginning February full test with cathode production and cathode transfer to dummy gun. A0 Photoinjector Prepared and changed cathode in the gun. QE now at about 10 %. 9

10 New cathode systems: LBNL 1E-10 New Pumping Configuration for long distance shipment Varian Ion Pump 20 ls 1 1 SAES NEG Pump D100 Pressure Pen nning (mbar) 8E-11 6E-11 4E-11 2E-11 Ion Pump OFF Ion Pump 8/5/2010 8/10/2010 8/15/2010 8/20/2010 8/25/2010 8/30/2010 Time QE = 11.1 % 10 mm Thenewbox SAES D100 NEG Pump Thefirst Cs 2 Te film 10

11 SAES NEG Pumps D100 NEXTorr (Include Ion Pump) 11

12 Conclusions The photocathode preparation chamber will be ready for cathode production end of January FNAL ready for final test of the complete apparatus. Bake out of the transfer system will follow the test. LBNL system under test to check cathode QE stability with only Getter Pump. 12