  The Low-Energy Demonstration Accelerator (LEDA) radio-frequency quadrupole
(RFQ) is a 100% duty factor (CW) linac that delivers >100 mA of H+ beam at 6.7
MeV. The 8-m-long, 350-MHz RFQ structure accelerates a dc, 75-keV, 110-mA H+
beam from the LEDA injector with >90% transmission. LEDA [1,2] consists of a
75-keV proton injector, 6.7-MeV, 350-MHz CW RFQ with associated high-power and
low-level rf systems, a short high-energy beam transport (HEBT) and high-power
(670-kW CW) beam stop. The beam emittance is inferred from wire scanner
measurements of the beam profile at a single location in the HEBT. The beam
profile is measured as a function of the magnetic field gradient in one of the
HEBT quadrupoles. As the gradient is changed the spot size passes through a
transverse waist. Measurements are presented for peak currents between 25 and
100 mA.
