Development of a strongly focusing high-intensity He+ ion source for a confined alpha particle measurement at ITER

Morozov

AIP Conference Proceedings

2015

Abstract. High beam polarization is essential to the scientific productivity of a collider. Polarized 3 He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding that achieved today are a key requirement for the development of these next generation high-luminosity high-polarization colliders. The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for realization of a new type of a polarized 3 He ion source. This report discusses a polarized 3 He ion source based on the large difference of extra-electron autodetachment lifetimes of the different 3 He ion hyperfine states. The highest momentum state of 5/2 has the largest lifetime of ~3 3 He ion beam composed of only the |5/2, 5/2> hyperfine states and then quenching one of the states by an RF resonant field, 3 He beam polarization of 90% can be achieved. Such a method of polarized 3 He production has been considered before; however, due to low intensities of the He + ion sources existing at that time, it was not possible to produce any interesting intensity of polarized 3 He ions. The high-brightness arc-discharge ion source developed at BINP can produce a high-brightness 3 He + beam with an intensity of up to 2 A allowing for selection of up to ~1-4 mA of 3 He ions with ~90% polarization. The high gas efficiency of an arc-discharge source is important due to the high cost of 3 He gas. Some features of such a PIS as well as prototype designs are considered. An integrated 3 He ion source design providing high beam polarization could be prepared using existing BNL equipment with incorporation of new designs of the 1) arc discharge plasma generator, 2) extraction system, 3) charge exchange jet, and 4) magnetic separation system.

Section: Figurementioning

confidence: 99%

Section: Potential Options For Production Of Polarized 3 He -Ionsmentioning

confidence: 99%

Polarized 3He− ion source with hyperfine state selection

Morozov

AIP Conference Proceedings

2015

Proceedings of XVth International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2013)

“…For this purpose, a 1 MeV, 10 mA He -ion source is under development (He + current should be ~3 A with low emittance), [11]. Electron autodetachment from metastable He-ions is used for production of the fast ground-state He 0 .…”

Section: He -Ionsmentioning

confidence: 99%

Perspective for development of a source of highly polarized 3He- ions

Dudnikov¹,

Dudnikov²

2014

High beam polarization is essential to the scientific productivity of a collider. Polarized 3 He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding those achieved today are a key requirement for the development of these next generation high-luminosity highpolarization colliders. A new version of a polarized 3 He -ion source is needed.In this article it is proposed a polarized 3 He -ion source based on the large difference of the autodetachment lifetimes of the different 3 He -ion hyperfine states. The highest momentum state of 5/3 has the largest lifetime of τ~350 μs while the lower momentum states have lifetimes of τ ~10 μs. By producing a 3 He -ion beam composed of only the |5/2, 5/2> hyperfine states and then quenching one of the states by an RF resonant field, 3 He-beam polarization of 95% can be achieved. A high-brightness arcdischarge ion-source can produce 3 He -beams with ~1mA current with ~90% polarization. An integrated 3 He -ion source design providing high beam polarization could be prepared based on existing BNL equipment that incorporates new designs of the 1) arc discharge plasma generator, 2) extraction system, 3) charge exchange jet, and 4) optimized magnetic separation system. The formation, extraction, and transport of the ion beams in the new source should be computer simulated. Manufacturing techniques should be explored using new materials and fabrication costs should be evaluated. The advanced 3 He -ion source can be built and tested on the BNL Test Stand for further use in the ion-ion RHIC and ion-electron colliders..

Review of Scientific Instruments

“…The beam current was measured by a Rogowski coil. 7 It was also estimated as I beam = I acc − I dec , where I acc and I dec were the acceleration and deceleration current, and by a current onto a carbon beam dump target (100 × 100 × t2 mm 3 ). Agreement among these three measurements was satisfactorily good 7 when the vacuum level was good.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…Extraction with concave electrodes 4 was chosen so that the extracted beam focuses into an acceptable size of an alkali vapor cell without using electrostatic lenses which extinguish the space charge neutralization. 5 We have reported on the design of the system, 5 the arc performance, 6 the preliminary results of the beam extraction, 7 and the optimization of the filament configuration. 8 A beam current more than 2 A was obtained at acceleration voltages of 20-25 kV with the arc power less than 10 kW.…”

Section: Introductionmentioning

confidence: 99%

Extraction of a strongly focusing He+ beam from three-stage concave electrodes for alpha particle measurement system in ITER

Kobuchi

Sasao

Kisaki

et al. 2012

Self Cite

Observation of threshold energy and hysteresis in high current ion beam guiding and transmission through a micro-glass-capillary Appl. Phys. Lett. 101, 223508 (2012) Empirical laws of particle extraction from single-grid source of bipolar ion-electron flow Rev. Sci. Instrum. 83, 113302 (2012) Moderately converging ion and electron flows in two-dimensional diodes Rev. Sci. Instrum. 83, 113301 (2012) Velocity map photoelectron-photoion coincidence imaging on a single detector Rev. Sci. Instrum. 83, 093103 (2012) Studies for aluminum photoionization in hot cavity for the selective production of exotic species project Rev. Sci. Instrum. 83, 02B317 (2012) Additional information on Rev. Sci. Instrum. A strongly focusing He + ion beam source equipped with concave multi-aperture electrodes was developed for production of He − through a charge exchange cell. The beam was extracted at a voltage less than 20 kV from 301 apertures distributed in an area of 100 mm φ, and focused at 750 mm distance. The beam current and the beam size of 2 A and 20 mm in diameter, respectively, were achieved with an arc power less than 10 kW. The optimum perveance was obtained at 0.02 A/kV 1.5 at the beam energy less than 20 keV which is suitable for the conversion to He − in an alkali vapor cell.