A pre-injector upgrade for ISIS, including a medium energy beam transport line and an RF-driven H− ion source

Lawrie, Scott; Abel, Robert; Cahill, C.; Faircloth, D. C.; Macgregor, John; Patel, Shrina; Morais-Sarmento, Tiago; Speed, Jonathan; Tarvainen, O.; Whitehead, Mark; Wood, T.; Zacek, D.

doi:10.1063/1.5127263

Cited by 5 publications

(5 citation statements)

References 11 publications

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“…The ISIS and SNS external coil sources have been described elsewhere in detail [3,[9][10][11][12][13]. They have similar designs which include an aluminium nitride ceramic plasma chamber, a plastic cooling jacket and a solenoidal RF-coil, as shown in figure 1.…”

Section: Methodsmentioning

confidence: 99%

RF efficiency measurements of inductively-coupled plasma H⁻ ion sources at accelerator facilities

Lawrie

Abel

Morais-Sarmento

et al. 2023

J. Phys. D: Appl. Phys.

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Experimental campaigns were undertaken to understand and improve the coupling efficiency of RF power into the plasma in three accelerator-based ion sources. Different matching circuit and mechanical engineering setups were used and the network resistance calculated. The efficiency was then measured for a range of RF frequencies and input gas flows. Coupling efficiencies of around 60% were measured in setups using RF-coils mounted external to the plasma chamber. The efficiency is improved to 80% when the coil is immersed in the plasma, allowing closer coupling. As well as the coil geometry, the isolation transformer required for beam production contributes to the overall losses.

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Section: Methodsmentioning

confidence: 99%

RF efficiency measurements of inductively-coupled plasma H⁻ ion sources at accelerator facilities

Lawrie

Abel

Morais-Sarmento

et al. 2023

J. Phys. D: Appl. Phys.

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“…The RF ion source design has been described previously in detail [17,18]. To summarise, a watercooled solenoid RF-coil is wound in air around a plain cylindrical-tube ceramic plasma chamber.…”

Section: Design Featuresmentioning

confidence: 99%

First H^- beam extracted from the non-caesiated external RF-coil ion source at ISIS

Lawrie,

Abel,

Cahill

et al. 2023

J. Inst.

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A high power, high duty-cycle, non-caesiated negative hydrogen ion source is in development at the ISIS pulsed spallation neutron and muon facility. Stable operation of an inductively-coupled plasma pulsing at 50 Hz, 1 ms, 70 kW has been perfected with no apparent lifetime issues. Novel features compared to similar H- sources include a very low power microwave ignition gun, an adjustable permanent magnet filter field and multiple large 3D-printed components. This paper details the initial commissioning efforts required to generate a beam. An H- beam current of 10 mA was extracted on the first try in pure volume-production mode. Parameter sweeps and optimisation to reach the required 35 mA were put on hold to address ancillary equipment problems. Mitigation of RF pickup required major mechanical changes such as additional screening and magnetic shielding. Extraction voltage holding capabilities were investigated to cope with co-extracted electron current loading in excess of 0.7 A. Preliminary studies of the biased plasma electrode current showed that co-extracted electrons could be suppressed by increasing the magnetic filter field and gas flow.

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“…1. To achieve full power and full duty cycle, improvements were made to several key components, compared to the design discussed in [3].…”

Section: Major Componentsmentioning

confidence: 99%

“…Moreover, poor beam transport efficiency along the linac means only 25 mA of beam is delivered to the synchrotron from the 55 mA created by the ion source. A project is underway to overhaul the 'pre-injector' section of the linac with a medium energy beam transport (MEBT) [3]. This will improve beam efficiency such that only 35 mA will be needed from the ion source.…”

Section: Introductionmentioning

confidence: 99%

Plasma commissioning in a high power external RF-coil volume-type H^- ion source

Lawrie

Abel

Faircloth

et al. 2022

J. Phys.: Conf. Ser.

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A high power, high duty cycle, negative hydrogen ion source is in development at ISIS. It will operate in pure volume-production mode and is driven by a 52-turn RF-coil mounted external to the plasma chamber. A solid-state amplifier with a maximum output of 100 kW in 50 Hz, 1 ms pulses delivers RF power to the coil via an impedance-matching network. The amplifier has a relatively wide bandwidth, able to deliver full power from 1.8-4.0 MHz. This flexibility allowed straightforward commissioning of the matching network into an inductively-coupled plasma. Striking of the pulsed plasma is facilitated by a compact microwave ignition gun, requiring only 10 W of power at 2.45 GHz to deliver 1 mA seed pulses of electrons. Experiments have shown that it is vital to encapsulate the RF-coil properly to mitigate high voltage sparking. In addition, the location of the coil relative to the ion source’s permanent magnets has a critical effect on the ease of plasma ignition. The result of commissioning work is that a full duty-factor (50 Hz, 800 ^s) plasma has been achieved at nominal operating power (30 kW) and detailed optical studies have begun.

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A pre-injector upgrade for ISIS, including a medium energy beam transport line and an RF-driven H− ion source

Abstract: The dual advanced ion simultaneous implantation experiment (DAISIE) for testing plasmafacing materials Review of Scientific Instruments 90, 103505 (2019);

Cited by 5 publications

References 11 publications

RF efficiency measurements of inductively-coupled plasma H⁻ ion sources at accelerator facilities

RF efficiency measurements of inductively-coupled plasma H⁻ ion sources at accelerator facilities

First H^- beam extracted from the non-caesiated external RF-coil ion source at ISIS

Plasma commissioning in a high power external RF-coil volume-type H^- ion source

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A pre-injector upgrade for ISIS, including a medium energy beam transport line and an RF-driven H− ion source

Abstract: The dual advanced ion simultaneous implantation experiment (DAISIE) for testing plasmafacing materials Review of Scientific Instruments 90, 103505 (2019);

Cited by 5 publications

References 11 publications

RF efficiency measurements of inductively-coupled plasma H− ion sources at accelerator facilities

RF efficiency measurements of inductively-coupled plasma H− ion sources at accelerator facilities

First H- beam extracted from the non-caesiated external RF-coil ion source at ISIS

Plasma commissioning in a high power external RF-coil volume-type H- ion source

Contact Info

Product

Resources

About

RF efficiency measurements of inductively-coupled plasma H⁻ ion sources at accelerator facilities

RF efficiency measurements of inductively-coupled plasma H⁻ ion sources at accelerator facilities

First H^- beam extracted from the non-caesiated external RF-coil ion source at ISIS

Plasma commissioning in a high power external RF-coil volume-type H^- ion source