Naval Postgraduate School

1. FEL Research at the Naval Postgraduate SchoolJoe Blau, John Lewellen, Bill Colson Physics DepartmentNaval Postgraduate SchoolXFEL Workshop, LBNL, Berkeley, CA, October 23, 2008

2. U.S. Marine Other U.S. Corps 5% 13% International U.S. Navy 19% 42% NPS Students: 1,556 from 88 nations U.S. Army 7% U.S. Coast U.S. Air Guard Force <1% 14% Naval Postgraduate School 100 Years of Graduate Military Education • 1909: Founded at the U.S. Naval Academy to provide the Fleet with a focused Engineering Program • 1951: Moved to Monterey, CA

3. NPS Physics Department • ~30 PhD faculty: Teaching and Research Faculty • ~80-100 Masters students onboard, ~5% PhD • Masters in Applied Physics (2 years) with Thesis • ~$7M/year research dollars: ONR, NSF, DOE, NAVSEA,… • ~$2M/year separate teaching budget • Areas of research specialization are varied, but include: • acoustics • weapons and weapons effects • free electron laser and railgun technologies • electro-optics and sensor physics • basic physics research • Large (~hundreds) civilian PhD initiative beginning now • U.S. civilians headed to industry and national laboratories

4. Faculty Bill Colson Joe Blau Bob Armstead Pete Crooker John Lewellen Technical Support Bill Armstrong Don Snyder Rich Swent Other Support Raquel Herold (admin) Eric Adint (computer) Ph.D. candidates LCDR Sean Niles CDR Ken Ferguson Master’s candidates LT Robert Neuerman LT Robert Edmonson LT Ben Wilder LTJG Aaron Zimmer LT Justin Jimenez LT Samuel Hallock Visiting Faculty Todd Smith (Stanford) Bill Graves (MIT) John Noonan (Argonne) Current NPS-FEL Group

5. NPS-FEL Plans • NPS-FEL vault & lab space will be completed soon (promised for end of CY08) • Cathode-related work on SCA injector • New booster / injector development in progress • Facilities build-out and population starting • Continue / Initiate NPS internal collaborations • NPS-FEL team needs to grow • already attracting more students • need to hire post-docs and staff researchers

6. Plans for FEL Laboratory • NPS internal funding • $1.2M for building rehab (starting up) • $250k for MW power upgrade (completed June ’08) • NAVMED safety approvals (start early ’09) • radiation • laser • Infrastructure installation (throughout ’09) • Cryogenic system • RF power sources • Interlock and other safety systems • Control system installation / expansion • Cathode experiments with SCA gun • QW booster cavity installation & testing • Start linac systems layout, installation & testing

7. Plans for the Guns • SCA Injector (230 kV DC) (through late ’09) • Photothermal cathode testing (w/ NRL, UMD) • Field emitter cathode testing (w/ Vanderbilt) • Niowave QW SRF gun (1.5 MeV, 500 MHz) (late ’09) • System on order – funds committed ($950k) • Gradient standoff & cavity commissioning • “Can it make beam?” testing • Start looking at loadlock and cathode systems (through ’09)

8. Plans for the LINAC • In-line linac configuration (late ’08 – mid ’09) • design • begin component purchase / build / install • Recirculator configuration (mid ’09) • design • redesign • Start measuring & characterizing our existing magnets (early ’09) • Potential: Modify cryomodules for local liquefaction (mid- to late ’09)

9. NPS FEL 4D Simulation • Cluster handles ~100 z-slices in optical pulse • Each slice follows (x,y) evolution of electrons and light • Typical simulation has 3x106 electrons, 16x106 sites • Fields and electrons evolve self-consistently in (x,y,z) • Electron pulse slips back relative to optical pulse NPS FEL Cluster optical wavefront a(x,y,z) optical pulse electrons z-slices electron phase space =1 =0 

10. Simulation Method • 4D multimode simulation in (x, y, z, t) • Parallelized to run on cluster computer • Uses self-consistent Lorentz-Maxwell equations • Includes betatron motion of electrons • Includes pulse slippage and optical diffraction • Linear or step-tapered undulator • Stability effects: shift and tilt electron beam • Expanding coordinates propagate light to first optic

11. Brookhaven SDL FEL Amplifier L = 10m Electron Beam: Energy: Eb = 101 MeV Trans. Emit: n = 4 mm-mrad Radius: rb = 0.21 mm Long. emit: l = 65 keV-ps Bunch charge: q = 0.35 nC Peak Current: Ipeak = 230 A Bunch Duration: tb = 1.5 ps Energy Spread = 0.1% Undulator (NISUS): Period: 0 = 3.89 cm Number of periods: N = 256 Length: L = 10 m Undulator parameter: Krms = 0.78 Seed Laser: Wavelength: = 0.79 m Peak power: Popt = 4 kW Pulse Duration: topt = 4.2 ps

12. SDL FEL: Comparison to Experiment Electron beam kinetic energy: Eb = 100.9 MeV (at resonance, 0 = 0) Extraction:  = 0.13% Final optical pulse energy: Eopt = 44 J (experiment: 43 J) Note final optical pulse shape is nearly flat-top Induced energy spread: / ≈ 2% Transverse profile shows higher-order modes

13. SDL FEL: Comparison to Detuning Experiment Electron beam kinetic energy increased by 0.4% Eb = 101.3 MeV (0 = 12) Final optical spectrum is broader; note sideband Extraction:  = 0.37% Final optical pulse energy: Eopt = 130 J (experiment: 134 J) Induced energy spread: / ≈ 2%

14. Plans for Simulation • Continue work on 4D FEL amplifier simulation • Improve methods for optical mode description (Laguerre and Hermite-Gaussian mode expansions) • Develop models for spontaneous emission / start-up noise to model SASE FEL designs • More comparisons to experiments, theoretical models and other simulations • Develop 4D FEL oscillator simulation • Already have 3D model, doesn’t include pulse effects • Study alternate approaches, e.g. ring resonator and RAFEL • Develop start-to-end model including accelerator, beamline and recirculation • Interface with existing particle beam codes (e.g., Parmela, elegant)

15. AES LANL Varian / CPI Diagnostics JLab Niowave Cryoplant Argonne INP-FEL primes Fermilab LINAC Systems Industry Livermore Control System NIU UMD National Labs RF Systems MIT UT Drive Lasers Stanford Port Hueneme Vanderbilt Gun Systems Pax River UCLA NRL NPS-FEL Navy Labs Academia Collaborations Map