FRAC: Fringing-RF-field-activated dc-to-pulse converter for low-energy ion beams.
Rev Sci Instrum
; 89(9): 095107, 2018 Sep.
Article
em En
| MEDLINE
| ID: mdl-30278761
ABSTRACT
We developed a new type of dc-to-pulse converter, called FRAC (Fringing-RF-field-Activated dc-to-pulse Converter) for low-energy ion beams electrostatically accelerated from an ion source. FRAC is based on a radio-frequency quadrupole (RFQ) linear trap technique and works in principle under ultrahigh vacuum conditions. Ions continuously injected into FRAC are decelerated by an alternating longitudinal electric field produced in a distorted radio frequency field around the edge region of RFQ rods. These ions accumulate in FRAC for a significantly long time. This edge effect appears most notably when the energy of incoming ions exceeds the injection barrier potential by less than a few eV and the energy spread is quite small. The ions stacked during the FRAC operation period are ejected as a high intensity pulsed beam. We investigated the performance of FRAC and the capability of some FRAC operation methods developed to enhance the dc-to-pulse conversion efficiency. The maximum conversion efficiencies achieved were 22% and 5.6% at FRAC operation frequencies of 10 and 1 Hz, respectively. The number of ions contained in an output beam pulse with a duration of 500 µs was in practice 1.6 × 109 ions/pulse at an injected dc beam intensity of 4.6 nA and an operation frequency of 1 Hz.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Rev Sci Instrum
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Japão