Engineering topics

Pennisi, Terry

Publications and source records attributed to Pennisi, Terry.

4 records

DOE OSTI2021

Recent performance of the SNS H - ion source with a record long run

The Spallation Neutron Source (SNS) accelerator system includes a 65 keV H - injector, a 2.5 MeV radio frequency quadrupole (RFQ), a 1 GeV linac chain (DTL-CCL-SCL) and an accumulator ring. The H - injector consists of an RF-driven, Cs-enhanced, multi-cusp H - ion source and a compact, two-lens electrostatic low energy beam transport (LEBT). In 2018, a new RFQ was installed in place of the original RFQ along with upgraded ion source support infrastructure. This paper presents the operational performance and some highlights of beam studies with the SNS ion source since the new RFQ was put into operation. SNS routinely operates at 1.4 MW average beam power for three run cycles per year. During the most recently finished run, FY20B, we operated a single source for the entire run spanning ~4 months with a >99.5% availability. A single dose of cesiation was conducted during the ion source startup which yielded ≥54 mA current for the entire run with just few minor adjustments of parameters.

Han, Baoxi↗

DOE OSTI2021

H- ion source research and development at the Oak Ridge National Laboratory

The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world's most intense pulsed neutron beams to a wide array of instruments which are used to conduct investigations in many fields of science and engineering. Neutrons are produced by spallation of liquid Hg due to bombardment of short (~1µs), intense (~35 A) pulses of protons delivered at 60 Hz from a storage ring which is fed by a high-intensity, 1 GeV H- LINAC. This facility has operated almost continuously since 2006, with ion source performance increasing over those years, and currently providing 50-60 mA of H- ions with a duty-factor of 6% for maintenance-free runs of ~120 days with near 100% availability. Ion source research and development at ORNL has played a key role in enabling and supporting these achievements: this report provides some historical highlights of this effort, describes our current ion source testing facilities, discusses the goals of the program and finally provides a snapshot of some of our ongoing R&D activities. In particular, we have recently simplified and improved the reliability of the plasma ignition gun for the external antenna ion source which is discussed in detail.

Welton, Robert F.↗

DOE OSTI2020

Tests of Cs-Free Operation of the SNS RF H⁻ Ion Sources

Tests were performed at SNS in collaboration with visiting colleagues from ISIS, UK to evaluate the uncesiated beam performance of the SNS RF H⁻ ion sources. Two spare experimental sources, one with internal antenna and one with external antenna were used for the tests. The beam currents achieved with Cs-free operations accounted for about 1/3 to 1/2 of the beam currents produced with cesiated operations. ~17 mA uncesiated H⁻ current was demonstrated within the tested RF power range up to 65 kW with the internal antenna source and ~15 mA with up to 40 kW RF with the external antenna source. In Cs-free operations, the power supply for the electron dumping electrode was loaded down below its set voltage but was not too drastic to tamper the operation.

Han, Baoxi↗

DOE OSTI2020

Installation and commissioning of the ion source systems for the new spallation neutron source 2.5 MeV injector

The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world’s most intense pulsed neutron beams to a wide array of instruments, which are used to conduct investigations in many fields of engineering, physics, chemistry, material science, and biology. Neutrons are produced by spallation of liquid Hg by the bombardment of short (∼1 µs), intense (∼35 A) pulses of protons delivered at 60 Hz by an accumulator ring which is fed by a high-intensity, 1 GeV, H− LINAC (linear accelerator). This facility has operated nearly continuously since 2006 but has recently undergone a 4-month maintenance period, which featured a complete replacement of the 2.5 MeV injector feeding the LINAC. The new injector was developed at ORNL in an off-line beam test facility and consists of an ion source, low energy beam transport, and a Radio Frequency Quadrupole (RFQ). This report first describes the installed configuration of the new injector detailing the ion source system. The first beam current, RFQ transmission, emittance, and energy measurements from the injector installed on the SNS are reported. These data not only show a significant performance improvement for our existing facility but will also make accessible the higher beam current requirements for future SNS upgrade projects: the proton power upgrade and second target station.

Welton, R. F.↗