Activities of FNPL from 02/14 - 02/18 Friday Feb 18 th, 2005 minutes at: http://nicadd.niu.edu/fnpl/Operation/Minutes/ * Plan for next week: Monday:.north cave run .laser work [Jinaliang. Rodion] - adjust grating and try to compress the bunch to 3.5 ps rms in the UV - optimize laser parameter to insure we can provide 8 nC/bunch .other: - repair floppy disk of the O-scop in control room [Jamie] Tuesday:.north cave run .laser work [Jinaliang. Rodion] - continue work of Monday .other - when north cave work is done start south cave and prepare beam for plasma lens experiment [Matt, operator Philippe] Wednesday: plasma lens experiment [Matt, operator Jamie] Thursday: plasma lens experiment [Matt, operator Jamie] round beam studies (?) [Rodion] Friday: flat beam DISCUSSIONS: * Last week activities: - most of the week we had trouble with the photocathode laser related to the UV pulse shape. - Monday the UV pulse shape was measured and the laser pulse was found to be double peaked or mon-peaked with a long pedestal, trying to tune the bandwidth did not improve much the situtation (though it seems it removed the double peak, the UV t-distribution still had a pedestal). The pulse stacker was used to generate flat top pulse, but because of the UV shape of a single pulse, the "flat top" distribution was not at all flat top. - Tuesday the oscillator lamp were changed (broken?) and in the afternoon further work on the UV pulse was done - Wednesday/Thursday: we try to run the flat beam experiment but for both day the beam shape was very ugly (non uniform) we again related this (by streaking UV) to the double peak distribution that had reappeared - Friday was dedicated to the laser, to set the grating properly, Jianliang bypassed the amplication chain and show that if he try to compress the CW IR with the grating we used he get an autocorrelation width of 41 ps (using the CW autocorrelator), while the autocorrelation width when using the test compressor is only 2.7 ps -- this indicated the grating of our compressor are not properly set. Furthermore, by using a mask in the high dispersion of the grating we could observe the x-y spot size on the cathode to be affected (in shape), this tends to suggest the dispersion downstream of the grating is not properly suppressed. * other: - Jianliang announced our oscillator from Time Bandwidth will be shipped to us mid-april and will then be delivered and installed by an enginner. Jianliang showed the work that need to be done in the laser room prior to the oscillator being installed: the table will be slighly moved not to touch each other and the new oscillator will be installed on the M-pass/2-pass table. The laser will only be on two tables now (one for oscillator + amplification stages, one for coubling frequency stages and diagnostics) - Philippe reported on some simulation of the 5 beamlets (quincunx) pattern use to produce a 5 spots on the cathode and measure the dynamics associated to the e- bunch. The simulations donw with impactT reproduce some of the feature. More data in a more controlled way need to be taken. ACTION ITEM updated: Mon Feb 21 10:45:52 CST 2005 H8/ calibration of upstream directional coupler and insulator (Markus need to speak to Tim and with Kai to schedule this STATUS?) H13/ Pulse stacker, what do we do? (Rodion) H21/ the laser uniformity problem can this be due to the new (since late summer) tight focusing in the doubling crystal area to improve conversion efficiency? On going work [Rodion] H33/ laser fluctuation since June 1st week [FIXED?] H34/ Need more work on power supply + devise a way to measure the current being put out to the magnet [Jamie] H36/ laser room/table vibration studies [Rodion] write up available [DONE} H39/ streak camera new optics for plasma OTR and UV laser streaking. [Jamie, Greg, Rodion, Philippe] UV works need to test OTR H40/ installation of UIUC experiment, beamline design [Philippe] H41/ OTRI experiment [Greg] H42/ revisit EO sampling experiment [Jianliang] H43/ laser cooling system upgrade [Jamie-> discuss with Adrian, Jianliang,Rodion Req written up -> Helen] H44/ do we need to get our rf system out of the TeV LCW and Why [Jamie/Philippe] H45/ O-scope floppy disk [Jamie] H46/ dying gun klystron [Tim K.->John Reid] #.46 from Adrian Melissinos: NEEDED LASER STUDIES: 2. beam profile (wavefront) studies both in IR and UV in laser room and on virtual cathode. Use spatial filters 3. study of doubling and quadrupling efficencies with old and new crystal, take a tuning curve POSSIBLE LASER UPGRADE PROJECTS 1. Measure IR pulse length before compression (use diode?) implement cw autocorrelation 2. Install new beamline between multipass and 2-pass -- install spatial filter, rebalance 2-pass amplifiers 4. _harware_: replacing all coolers with new system IV + use existing system III as back-up (see H43) 5. pulse stacker studies, new pulse stacker R&D (see H13)