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Two-Bunch PWFA Experimental Measurements & Procedures. FACET PWFA Collab . Meeting 5-20-2013 Mike Litos. Experimental Setup. Pre-ionized plasma column from laser Aligned to e-beam O(1mm) diameter Full extent of oven Beam prepared for two-bunches “Boring” drive beam – not ionizing gas
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Two-Bunch PWFA Experimental Measurements & Procedures FACET PWFA Collab. Meeting 5-20-2013 Mike Litos
Experimental Setup • Pre-ionized plasma column from laser • Aligned to e-beam • O(1mm) diameter • Full extent of oven • Beam prepared for two-bunches • “Boring” drive beam – not ionizing gas • Drive: sz ~ 35µm, charge ~ 7E9 • Witness: sz ~ 20µm, charge ~ 3E9 • Separation: 130µm • Lithium oven • plasma length: 30cm flat-top • plasma density: 5E16 cm-3 • Gas • plasma length: determined by laser • plasma density: continuous variation • plasma diameter: thin filament
Experimental Measurements • Beam loading – charge + phase • Charge Notch + Jaw Collimator • Phase Notch + Jaw Collimator • Phase Gas Pressure: fast • E-gain/charge tradeoff • Notch Collimator • Emittance growth measurement • Jaw Collimator • Head erosion (max achievable E-gain) • Emittance Spoiler Foil • Pre-Ionized vs. Self Ionized Laser • Transverse offset • TCAV, Dx Knob • Density scaling* • Oven Temp. + Pressure • Gas Pressure: fast • *need to find good Notch Coll. config. for each density
(Potential) Experimental Challenges • Laser ionized buffer gas in ramps? • Trapped charge loading wake? • Loading from low-energy tail? • Transformer ratio measurement when decelerated charge off scale? • Complications due to thin plasma filament in gas? • Immeasurable radial density profile • Significant uncertainty in alignment