COIL Chemical Oxygen Iodine Laser; operates at 1.315 μm

cryomodule a cryostat containing accelerating cavities and ancillary equipment such as tuners, couplers, and HOM loads

CSR coherent synchrotron radiation; coherent long-wavelength emission from the beam end that can cause emittance growth

cw continuous wave; an electromagnetic wave of constant amplitude and frequency

DC HV gun electron gun that relies on a direct current (DC) and high voltage (HV) applied across plates as the accelerating gradient for the electrons extracted from the cathode surface; a typical accelerating voltage is 300-500 kV over about 12-14 cm until the gun exit

DF deuterium fluoride; these lasers operate at a wavelength over a series of lines from 3.6 μm to 3.9 μm

DOE Department of Energy

emittance measure of beam quality that is related to the product of beam divergence and spot size

ERL energy recovery linac

FEL free-electron laser

field emission the emission of electrons from the solid-state surface caused by applying high electric fields perpendicular to the surface

FWHM full width at half maximum

FPC fundamental power coupler

“generation” nomenclature The synchrotron radiation sources of the past and present can be defined as follows:

• First-generation machines are electron synchrotrons and storage rings that were built for other purposes—for example, high-energy and nuclear physics—but whose bending magnet radiation was parasitically used by synchrotron radiation “users.” This radiation covered many wavelength regimes due to the nature of the bending magnet emission. In addition, the machines produced rather large photon source sizes as the electron beam emittance was large and neither intended for nor ideal for synchrotron radiation applications.

• Second-generation machines are machines dedicated for synchrotron radiation users that employ bending magnets as the primary source of synchrotron radiation. The beam emittances were designed by the machine architects to be smaller in order to provide users with a smaller source size and greater brilliance.

• Third-generation machines are also dedicated for synchrotron radiation users and were designed to accommodate many so-called insertion device magnets, such as undulator and