New development of advanced superconducting electron cyclotron resonance ion source SECRAL (invited)

Abstract

Superconducting electron cyclotron resonance ion source with advance design in Lanzhou (SECRAL) is an 18–28 GHz fully superconducting electron cyclotron resonance (ECR) ion source dedicated for highly charged heavy ion beam production. SECRAL, with an innovative superconducting magnet structure of solenoid-inside-sextupole and at lower frequency and lower rf power operation, may open a new way for developing compact and reliable high performance superconducting ECR ion source. One of the recent highlights achieved at SECRAL is that some new record beam currents for very high charge states were produced by 18 GHz or $18+14.5\text{GHz}$ double frequency heating, such as $1e\mu \text{A}$ of ${{}^{129}\text{X}\text{e}}^{43+}$ , $22e\mu \text{A}$ of ${{}^{209}\text{B}\text{i}}^{41+}$ , and $1.5e\mu \text{A}$ of ${{}^{209}\text{B}\text{i}}^{50+}$ . To further enhance the performance of SECRAL, a 24 GHz/7 kW gyrotron microwave generator was installed and SECRAL was tested at 24 GHz. Some promising and exciting results at 24 GHz with new record highly charged ion beam intensities were produced, such as $455e\mu \text{A}$ of ${{}^{129}\text{X}\text{e}}^{27+}$ and $152e\mu \text{A}$ of ${{}^{129}\text{X}\text{e}}^{30+}$ , although the commissioning time was limited within 3–4 weeks and rf power only 3–4 kW. Bremsstrahlung measurements at 24 GHz show that x-ray is much stronger with higher rf frequency, higher rf power. and higher minimum mirror magnetic field (minimum B). Preliminary emittance measurements indicate that SECRAL emittance at 24 GHz is slightly higher that at 18 GHz. SECRAL has been put into routine operation at 18 GHz for heavy ion research facility in Lanzhou (HIRFL) accelerator complex since May 2007. The total operation beam time from SECRAL for HIRFL accelerator has been more than 2000 h, and ${{}^{129}\text{X}\text{e}}^{27+}$ , ${{}^{78}\text{K}\text{r}}^{19+}$ , ${{}^{209}\text{B}\text{i}}^{31+}$ , and ${{}^{58}\text{N}\text{i}}^{19+}$ beams were delivered. All of these new developments, the latest results, and long-term operation for the accelerator have again demonstrated that SECRAL is one of the best in the performance of ECR ion source for highly charged heavy ion beam production. Finally the future development of SECRAL will be presented.