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[en] LCLS hardware availability has been above 90% for the first two commissioning runs of the accelerator. In this paper we compare the reliability data for LCLS (availability, MTBF and MTTR) to those of PEP-II, the e+e- collider operating previously at SLAC. It may be seen that the linac availability is not significantly different now than it was before, while the availability of the whole LCLS facility is significantly higher than that of the PEP-II facility as a whole (which was about 87%). Most of the improvement is in the MTTR. Ways to improve availability towards the goal of 95% are discussed.
[en] The linac at the Stanford Linear Accelerator (SLAC) runs routinely with a beam loading of around 12% for the fixed target experiment E-158. Typical energy spread and energy jitter are 0.1% and 0.05%. To explore the conditions for the Next Linear Collider (NLC) the linac was operated with 20% beam loading. This was attained by increasing the beam charge from 5 · 1011 to 9 · 1011 particles and increasing the pulse length from 250 ns to 320 ns. Although the beam loading compensation was more difficult to achieve, a reliable operating point was found with a similar energy spread and energy jitter as at the lower loading. Furthermore, using the sub-harmonic buncher (SHB), the beam was bunched at 178.5 MHz instead of the nominal 2.8 GHz so that the charge from 16 adjacent buckets was combined into one. Increased transverse instability and beam losses along the linac were observed indicating the possible onset of beam break-up
[en] In this note, the analysis on linac quadrupole misalignment is presented for the FACET linac section LI05-09 plus LI11-19. The effectiveness of the beam-based alignment technique is preliminarily confirmed by the measurement. Beam-based alignment technique was adopted at SLAC linac since SLC time. Here the beam-based alignment algorithms are further developed and applied in the FACET commissioning during 2012 run.
[en] The LCLS project at SLAC requires 40 undulators: 33 in the beam line, 6 spares, and one reference undulator. A new facility was constructed at SLAC for tuning and fiducializing the undulators. The throughput of the facility must be approximately one undulator per week. The undulator tuning has been partially automated. Fiducialization techniques have been devised. The new facility, the tuning techniques, and the fiducialization techniques will be discussed
[en] The discovery and impact of the principle of strong focusing was celebrated at a history Symposium at Stanford on 25 July in the course of the 1985 US Summer School on Particle Accelerators. Burt Richter, Stanford Linac Director, who introduced all the speakers with well chosen reminders about their various contributions related to the theme of the symposium, remarked that it was an appropriate time to be lauding the great contributions of accelerator physicists following the Nobel Prize award to Simon van der Meer for outstanding achievements in accelerator physics
[en] This note will show how to increase the SLED  gradient by varying Qe, the external Q of the SLED cavity, by increasing its Q0 and by increasing the compression ratio. If varying the external Q is to be effective, then the copper losses should be small so that Q0 >> Qe. Methods of varying Qe will be indicated but no experimental data will be presented. If we increase the klystron pulse width from 3.5 to 5 (micro)S and increase Q0 from the present 100000 to 300000, then the gradient increases by 19% and the beam energy increases from 50 to 60 GeV. This note will also discuss SLED operation at 11424 MHz, the NLC frequency. Without Qe switching, using SLED at 11424 MHz increases the SLAC gradient from 21 MV/m to 34 MV/m, and at the same repetition rate, uses about 1/5 of rf average power. If we also double the compression ratio, we reach 47 MV/m and over 100 GeV beam energy
[en] The phase noise of the Main Drive Line (MDL) at the Stanford Linear Accelerator Center is extremely important to the operation of the linac since the MDL provides the radio frequency (RF) drive and phase reference for the entire accelerator system. In order to ensure that the Linac Coherent Light Source (LCLS) can be run using current MDL components, the phase noise of the MDL had to be ascertained. This was determined using an ultra-stable reference oscillator phase-locked to the MDL. Using this device, the phase noise was determined to be far greater than LCLS requires. This suggests that an improved Master Oscillator needs to be obtained in order to be able to run LCLS on the SLAC linac
[en] Design of the first generation LCLS injector is nearing completion. Fabrication has begun and component installation is planned for 2006. We discuss the last modifications made on both the 1.6 cell S-Band RF gun and the SLAC S-Band accelerating structures to minimize irreversible emittance growth. The mode separation between the 0 and π modes was increased from 3.4 MHz to 15 MHz. Dual feed and racetrack shapes have been incorporated in the full cell of the new gun. The linac sections were also modified to accommodate dual feeds and racetrack shapes in their input cells. PARMELA simulations indicating the need for these modifications are presented
[en] The beam for FACET (Facility for Advanced aCcelerator Experimental Tests) at SLAC requires an energy-time correlation ('chirp') along the linac, so it can be compressed in two chicanes, one at the midpoint in sector 10 and one W-shaped chicane just before the FACET experimental area. The induced correlation has the opposite sign to the typical used for BNS damping, and therefore any orbit variations away from the center kick the tail of the beam more than the head, causing a shear in the beam and emittance growth. Any dispersion created along the linac has similar effects due to the high (>1.2% rms) energy spread necessary for compression. The initial huge emittances could be reduced by a factor of 10, but were still bigger than expected by a factor of 2-3. Normalized emittance of 3 (micro)m-rad in Sector 2 blew up to 150 (micro)m-rad in Sector 11 but could be reduced to about 6-12 (micro)m-rad, for the vertical plane although the results were not very stable. Investigating possible root causes for this, we found locations where up to 10 mm dispersion was created along the linac, which were finally verified with strong steering and up to 7 mm settling of the linac accelerator at these locations.