Beamline Parameters

• Electron beam energy: 25 to 76 MeV
• Temporal structure: Macropulse length: 3 microseconds
  Macropulse repetition rate from under 1 PPS to 3 PPS.
  Micropulse repetition period 12.25 ns or 24.5 ns.
  Micropulse length variable from about 1 ps FWHM to 10 ps FWHM.
• Electron beam charge: continuously variable.
  Single micropulse charge from zero to a few nanoculombs.
  Bunch train charge up to about 10 nanoculombs. 
•  Emittance: depends on various conditions, e.g. peak current, gun field, microbunch length etc. At 1 nC we have measured the emittance at 2.6 mm mrad (rms normalized) at a bunch length of 10 ps FWHM. The local emittance (Slice Emittance) is smaller, measured 1.4 mm mrad for a slice out of the 1 nC bunch.
• Stability: (approx.) 1 ps in short term phase, 1% of beam diameter pointing, 1%-2% relative charge.

Some of the measured results below have been presented by D.T. Palmer, X.-J. Wang, R.H. Miller, I. Ben-Zvi, C. Pellegrini, J. Sheehan, J. Skaritka, H. Winick, M. Woodle and V. Yakimenko, Commissioning Results of the Next Generation Photoinjector, Proc. 7th Advanced Accelerator Concepts Workshop, Lake Tahoe, Oct. 13-18, 1996

• Electron bunch length (full width, ps) vs. charge for three rf phases.
• Measured normalized rms emittance as a function of the laser to rf phase at a constant laser enegy.
• Measured normalized rms emittance as a function of the charge at a constant laser to rf phase.
• Measured charge, pulse length and the resultant current as a function of the phase at a constant laser energy.
• Electron charge vs. laser intensity, various cathodes and cleaning conditions. The charge is in nano Coulombs, the UV (quadrupled YAG) laser energy in microJoules.