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The LANSCE accelerator is currently powered by a filament-driven, biased converter-type H− ion source that operates at 10%, the highest plasma duty factor for this type of source, using only ∼2.2 SCCM of H2. The ion source needs to be replaced every 4 weeks, which takes up to 4 days. The measured negative beam current of 12–16 mA falls below the desired 24 mA acceptance of the LANCSE accelerator. The SNS (Spallation Neutron Source) RF-driven, H− ion source injects ∼50 mA of H− beam into the SNS accelerator at 60 Hz with a 6% duty factor and an availability of >99.5% but requires ∼30 SCCM of H2. Up to 7 A h of H− have been produced during the 14-weeks-long source service cycles, which is unprecedented for small emittance, high-current, pulsed H− ion sources. The emittance of the SNS source is slightly smaller than the emittance of the LANSCE source. The SNS source also features unrivaled low Cs consumption and can be installed and started up in <12 h. LANSCE and SNS are working toward the use of SNS H− ion sources on the LANSCE accelerator because they could (a) fill the LANSCE accelerator to its capacity, (b) decrease the source replacement time by a factor of up to 7, and (c) increase source lifetime by a factor of about 4. This paper discusses some of the challenges that emerge when trying to match a different H− source into an existing injector with significantly different characteristics and operating regimes. [ABSTRACT FROM AUTHOR]

The Spallation Neutron Source operates reliably at 1.2 MW and will gradually ramp to 1.4 MW. This paper briefly recalls some of the struggles when the unprecedented project was started and ramped to 1 MW over a 3½ year period. This was challenging, especially for the H− ion source and the low-energy beam transport system, which make up the H− injector. It took several more years to push the H− injector to the 1.4 MW requirements, and even longer to reach close to 100% injector availability. An additional breakthrough was the carefully staged, successful extension of the H− source service cycle so that disruptive source changes became rare events. More than 7 A·h of extracted H− ions have been demonstrated with a single source without maintenance, more than twice the single-source quantity of ions produced by any other high-current H− accelerator facility. Achieving the 1.4 MW requirements with close to 100% availability and record-breaking source service cycles were the basis for the 2017 Brightness Award. [ABSTRACT FROM AUTHOR]

Recent measurements of the H- beam current show that SNS is injecting about 55 mA into the RFQ compared to ~45 mA in 2010. Since 2010, the H- beam exiting the RFQ dropped from ~40 mA to ~34 mA, which is sufficient for 1 MW of beam power. To minimize the impact of the RFQ degradation, the service cycle of the best performing source was extended to 6 weeks. The only degradation is fluctuations in the electron dump voltage towards the end of some service cycles, a problem that is being investigated. Very recently, the RFQ was retuned, which partly restored its transmission. In addition, the electrostatic low-energy beam transport system was reengineered to double its heat sinking and equipped with a thermocouple that monitors the temperature of the ground electrode between the two Einzel lenses. The recorded data show that emissions from the source at high voltage dominate the heat load. Emissions from the partly Cs-covered first lens cause the temperature to peak several hours after starting up. On rare occasions, the temperature can also peak due to corona discharges between the center ground electrode and one of the lenses. [ABSTRACT FROM AUTHOR]

Since 2009, the Spallation Neutron Source (SNS) has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of ∼50 mA H- ions from the ion source with a ∼5% duty factor. The 50 mA are achieved after an initial dose of ∼3 mg of Cs and heating the Cs collar to ∼170 °C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H- beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 °C. [ABSTRACT FROM AUTHOR]

We present a self-consistent method for analyzing measured emittance data that yields unbiased estimates for the root-mean-square (rms) emittance. The self-consistent, unbiased elliptical exclusion analysis uses an ellipse to determine the bias from the data outside the ellipse, before calculating the rms emittance from the bias-subtracted data within the ellipse. Increasing the ellipse size until the rms emittance estimate saturates allows for determining the minimum elliptical area that includes all real signals, even those buried in the noise. Variations of the ellipse shape and orientations are used to test the robustness of the results. Background fluctuations cause fluctuations in the rms emittance estimate, which are an estimate of the uncertainty incurred through the analysis. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We built a cryogenic electron-beam ion source which is now in operation. We report some experiences and results of the start-up phase, which was aimed at producing beams of highly charged argon. In March 1989 the first ions were extracted and identified as argon 17 + using Donets' x-ray technique. In April we started performing diagnostics with a 90° double-focusing analyzing magnet to study the charge-state distributions. In June we extracted beams with fully stripped argon 18 + as the most abundant argon charge state. [ABSTRACT FROM AUTHOR]

Investigates the production of highly charged ion beams with an electron beam ion source. Effect of the ion-confining downstream dam voltage on the ions; Reduction of the energy spread of the ions by elevating the main trap voltage; Generation of intense ion bunches through the combination of microbunching and direct current batch mode expulsions.

Introduces two modes of operation which combine the high yields of the high charge states obtained with batch mode productions with the high duty cycles obtained with continuous mode operations. Duty cycles and ion yields of ion beams produced via the leaky batch mode; Percent production of constant intensity ion beams and ion yields via the direct current batch mode.

The CRYogenic electron beam ion source at Kansas State University has been in operation since spring 1989. It produces up to Ar[sup 18+], Kr[sup 34+], and Xe[sup 44+] on a regular basis. Acceleration tubes and a beamline system were added during 1990. The ion source is mounted on a high voltage platform, which can be used to vary the ion energies between 2 and 200 kV per charge. The extraction-, analyzing-, and beamline systems were designed to accept a wide range of ion masses and charge states with the mass energy product (M·E/q²) stretching over four orders of magnitude. The system is used to study the low-energy highly charged ions interacting with electrons, atoms, thin foils, and surfaces. [ABSTRACT FROM AUTHOR]

Information about the topics discussed at the 13th International Conference on Ion Sources (ICIS) held in Gatlinburg, Tennessee from September 20-25 is presented. Topics include electron cyclotron resonance ion sources (ECRISs), negative ion sources and electron beam ion sources and traps (EBIS/T). The conference featured more than 200 scientists, engineers, students and vendors from 21 countries including Julien Bergoz, Jose Alonso and Claude Lyneis.

The Spallation Neutron Source operates reliably at 1.2 MW and will gradually ramp to 1.4 MW. This paper briefly recalls some of the struggles when the unprecedented project was started and ramped to 1 MW over a 3½ year period. This was challenging, especially for the H - ion source and the low-energy beam transport system, which make up the H - injector. It took several more years to push the H - injector to the 1.4 MW requirements, and even longer to reach close to 100% injector availability. An additional breakthrough was the carefully staged, successful extension of the H - source service cycle so that disruptive source changes became rare events. More than 7 A·h of extracted H - ions have been demonstrated with a single source without maintenance, more than twice the single-source quantity of ions produced by any other high-current H - accelerator facility. Achieving the 1.4 MW requirements with close to 100% availability and record-breaking source service cycles were the basis for the 2017 Brightness Award.

Recent measurements of the H(-) beam current show that SNS is injecting about 55 mA into the RFQ compared to ∼45 mA in 2010. Since 2010, the H(-) beam exiting the RFQ dropped from ∼40 mA to ∼34 mA, which is sufficient for 1 MW of beam power. To minimize the impact of the RFQ degradation, the service cycle of the best performing source was extended to 6 weeks. The only degradation is fluctuations in the electron dump voltage towards the end of some service cycles, a problem that is being investigated. Very recently, the RFQ was retuned, which partly restored its transmission. In addition, the electrostatic low-energy beam transport system was reengineered to double its heat sinking and equipped with a thermocouple that monitors the temperature of the ground electrode between the two Einzel lenses. The recorded data show that emissions from the source at high voltage dominate the heat load. Emissions from the partly Cs-covered first lens cause the temperature to peak several hours after starting up. On rare occasions, the temperature can also peak due to corona discharges between the center ground electrode and one of the lenses.