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L1S after AIP (2013). M. Ross, March 7, 2013. Schedule update. Theoretical PFN voltage stability and regulation range. Power supply rated: 50kV, 2.5kJ/sec peak, 40kHz switching freq. Peak charge current: Ipk = 2 ( Ppk / Vrated ) = 2(2.5kJ/50kV) = 100mA Voltage variations:
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L1S after AIP (2013) M. Ross, March 7, 2013
Schedule update Minh Nguyen AIP Review 2/20/2013
Theoretical PFN voltage stability and regulation range • Power supply rated: 50kV, 2.5kJ/sec peak, 40kHz switching freq. • Peak charge current: • Ipk = 2 (Ppk /Vrated) = 2(2.5kJ/50kV) = 100mA • Voltage variations: • ∆V = Ipk x 0.5Tsw /Cpfn= 100mA x 12.5µs/0.7µF = 1.78V • Pulse to pulse repeatability: • 1.78V / 50kV = 36 ppm • Charging voltage-time ratio: • Vchg/Tchg = Ipk /Cpfn = 100mA /0.7µF = 143 V/ms • For 4ms charge time (120Hz operation) Vchg = 572V • PFN voltage regulation range = 572V / 50kV = 1.1% Minh Nguyen AIP Review 2/20/2013
Ling Pulse stability: • At 100 ppm – L1S contributes 25% of total observed energy jitter LCLS injector stability March 7, 2013
Modulator upgrade circuit (in red lines) Modulator Output: 360 kV, 420 A , 151 MW peak, 91 kW Ave. @ 120 Hz LCLS injector stability March 7, 2013
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PFN monitor • PFN charging stability is generally assumed to be critical. • PFN voltage diagnostics? • Klystron / Thyratron studies? • Filament • Magnet • Stability • Drive LCLS injector stability March 7, 2013
Teledyne LeCroy: • 6 ppm offset voltage step resolution (best case) at 100 MHz – Recommend this equipment to be permanently installed and developed as an integrated diagnostic LCLS injector stability March 7, 2013
Possible L1S Studies • ‘Heater hum’ (60 Hz filament transformer 5045 beam steering) • Known source of 60 Hz. • Instability is seen when the linac timing shifts phase wrt transformer AC • Klystron magnet • Magnet PS stability ? • Klystron stability • Harmonic content and drive mapping All of the above will require observation with higher resolution probes following AIP completion. LCLS injector stability March 7, 2013