Lifetime and damage threshold properties of reflective x-ray coatings for the LCLS free-electron laser
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TMO specific boxes for AMI developed at SLAC National Accelerator Laboratory.
Materials used for hard x-ray-free-electron laser (XFEL) optics must withstand high-intensity x-ray pulses. The advent of the Linac Coherent Light Source has enabled us to expose candidate optical materials, such as bulk B 4 C and SiC films, to 0.83 keV XFEL pulses with pulse energies between 1 μJ and 2 mJ to determine short-pulse hard x-ray damage thresholds. The fluence required for the onset of damage for single pulses is around the melt fluence and slightly lower for multiple pulses. We observed strong mechanical cracking in the materials, which may be due to the larger penetration depths of the hard x-rays.
We built a two-mirror based X-ray split and delay (XRSD) device for soft X-rays at the Linac Coherent Light Source free electron laser facility. The instrument is based on an edge-polished mirror design covering an energy range of 250 eV-1800 eV and producing a delay between the two split pulses variable up to 400 femtoseconds with a sub-100 attosecond resolution. We present experimental and simulation results regarding molecular dissociation dynamics in CH3I and CO probed by the XRSD device. In conclusion, we observed ion kinetic energy and branching ratio dependence on the delay times which were reliably produced by the XRSD instrument.
Here, we present a 100 kHz, sub-20 fs optical parametric chirped-pulse amplifier (OPCPA) system delivering 88.6 W average power at a center wavelength of 800 nm. The seed pulses are derived from the pump laser via white-light continuum generation and are amplified in three non-collinear OPCPA stages. The final two high-power stages are pumped with a 661 W Yb:YAG InnoSlab amplifier. A simple and robust design is used for the OPCPA system to avoid thermal effects and enhance long-term stability, resulting in excellent beam quality and high conversion efficiency. To the best of our knowledge, this is the highest average power OPCPA system reported to date.
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Seebeck effect of metals play an important role in cryomodule design. As cryomodule cools down from room temperature down to nominal cavity operating temperature, components in a cryomodule experiences different temperatures. Some components such as power couplers cross from room temperature to 2 K. Thermo electric current forms loops circulating through and around cavities. Such current loops will generate additional magnetic field that could be trapped into cavity wall during superconducting transition as well as during cavity quench. These trapped field can degrade cavity quality factor and increase heat load. Simple circuit model is proposed and compared to calculated trapped field during cryomodule tests.
Monte Carlo simulations of the spontaneous radiation at low and high energies up to the Near Experimental Hall entrance yield beam widths for use in the design of transport and diagnostic instruments in the Front End Enclosure.
Measurements of the earth's magnetic field at several locations at SLAC were conducted to determine the possible field error contribution from tuning the undulators in a location with a different magnetic field than that which will be found in the undulator hall. An average difference of 0.08 {+-} 0.04 Gauss has been measured between the downward earth's field components in the test facility and SLAC tunnel locations.
Comprehensive measurements for photon and neutron radiation doses generated from laser-plasma interaction at SLAC’s MEC laser facility have been conducted. The goals of the measurements were to; determine the radiation dose per laser shot as a function of laser, optic and target parameters that are relevant to the MEC laser operations; validate the RPD-developed analytic model for photon dose calculations; and evaluate the performance of various types of passive and active detectors in the laser-induced radiation fields.
In this paper, a study of Silica is presented using a novel X-ray probe. The value of this X-ray source will be clearly defined, and diagnostic results will be presented.
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A collaboration between Fermilab, SLAC and ORNL is working to develop plasma processing for 1.3GHz TESLA shaped SRF cavities. Hydrocarbon (C x H y ) contaminations and adsorbates lower the cavity surface work function (Φ) increasing Field Emission (FE). Plasma processing removes C x H y allowing the cavity to operate at higher E acc .
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Explore the source record for details and available documents.
Explore the source record for details and available documents.