1. E-217 FACET users meeting 9/15/14 Ken Marsh

2. What happens to the experiment when laser fires full power in Lithium? Do we ionize the helium buffer zones? – maybe partially anyway Does laser breakup in transmitting optics – Probably, SPM, pulse splitting – Solution, pulse stretch, as opposed to reduce energy – Solution, remove window after compressor. – Solution reflective axicon. Does laser self compress in windows and lithium? – Probably, laser is chirped to reverse chirp in optics and lithium How significant are the optical nonlinearities in lithium? – Somewhat worried about n2 effects Wake location moves wrt to beam depends on preionization Your thoughts

3. Ionization injection experiments will require H2 plasma. Cannot see how to do controlled ionization injection in lithium. Concerned about using argon in single short bunch Multiple ionization levels Ar+ Ar++ due to laser and e-beam Argon + gammas = sulfur

4. Benefits of preionized H2 experiments Drive beam full pump depletion requires ~ 3-4 meter long plasma Expect very homogeneous plasma. Easily controlled plasma density. Plasma length controlled by axicon apertures. No unwanted self-trapping. No bizarre laser lithium or helium ionization issues. No concerns about e-beam ionized helium in plasma exit up ramp. Can do OTR beam optics measurements. Interesting to do e-beam ionized H2 experiments

5. Issues with preionized H2 plasma Can we ionize a large enough diameter plasma? – Rb < plasma radius Can we maintain required laser to electron beam alignment? Concern that collapsed e-beam will self ionize and propagate to the Be window – hopefully this will be limited by head erosion – Problem not observed in self ionized argon experiment Can we observe start of plasma in viewport? – Test at ucla Can we put beam waist at start of plasma? – No oven allows use of multi OTR beam fit No density ramp to reduce beam oscillations in plasma – Plan to have small beta beam configs available. – Expect large flux of hard x-rays for large mismatched beams.

6. Injector Design 6 H 2 /He IN Start of H 2 Plasma Pulsed Valve e-beam + Laser -> Helium Injection Zone

7. Experimental Setup 7 H 2 IN H 2 /He IN Gas Reservoir Pulsed Valve e-beam + Laser Hydrogen Chamber ->

8. E-217 Development at UCLA Map parameter space of injector – Measure, helium profile, timing, pressure vs density, rate of contamination etc. – Can we laser ionize H2 w/o ionizing helium. Profiles from laser ionization Imaging spectroscopy to locate helium zone – Helium emission lines Interferometry? Phase contrast?

9. E-217 hardware list (partial) 20 GeV 10kA linac preionzed hydrogen plasma 1 meter long Facet tunnel vacuum hardware- existing Turbo pump Remote actuated angle valve? H2 Fill valve H2 Drain valve Vacuum gauges Controls 6” Cube hardware-SLAC 6” cube 6” windows cameras for viewing plasma Injector- UCLA injector jet or capillary assembly ultra-torr feed through, 6” conflat fast valve and controller Solenoid type, ~100 us piezo type, ~10 us Helium fill assy and contro l- SLAC Helium or helium mix bottle in gallery SST gas line to IP (existing) Dry scroll pump Drain helium valve Add helium valve Helium reservoir 0-1000 Torr CM vacuum gauge Controls Fast valve controls- SLAC TTL variable width and delay to valve controller Cable from gallery to fast valve