H. W. Zhao

The heavy ion cooler-storage-ring project (HIRFL-CSR) at Lanzhou

HIRFL-CSR, a new ion Cooler-Storage-Ring (CSR) project, is the post-acceleration system of the Heavy Ion Research Facility in Lanzhou (HIRFL). It consists of a main ring (CSRm) and an experimental ring (CSRe). From the HIRFL cyclotron system the heavy ions will be accumulated, cooled and accelerated in the CSRm, then extracted fast to produce radioactive ion beams (RIB) or highly charged heavy ions. Those secondary beams will be accepted and stored by the CSRe for many internal-target experiments with electron cooling.

Advanced superconducting electron cyclotron resonance ion source SECRAL: Design, construction, and the first test result

Superconducting electron cyclotron resonance (ECR) ion source with advanced design in Lanzhou (SECRAL) is a next generation ECR ion source and aims for developing a very compact superconducting ECR ion source with a structure and high performances for highly charged ion-beam production. The ion source was designed to be operated at 18GHz at initial operation and finally will be extended to 28GHz. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. At full excitation, this magnet assembly can produce peak mirror fields on the axis of 3.6T at injection, 2.2T at extraction, and a radial sextupole field of 2.0T at plasma chamber wall. What is different from the traditional design, such as LBNL VENUS and LNS SERSE, is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the so...

Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL (invited)

There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e microA of O(7+), 505 e microA of Xe(20+), 306 e microA of Xe(27+), and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

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

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 GHz double frequency heating, such as 1 e microA of (129)Xe(43+), 22 e microA of (209)Bi(41+), and 1.5 e microA of (209)Bi(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 455 e microA of (129)Xe(27+) and 152 e microA of (129)Xe(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)Xe(27+), (78)Kr(19+), (209)Bi(31+), and (58)Ni(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.

Development of ECR ion sources in China (invited)

Recent development of electron cyclotron resonance (ECR) ion sources in China is reviewed. Emphasis is put on high charge state ECR ion sources which have been mainly developed in China by Institute of Modern Physics (IMP). Presently two ECR ion sources built by IMP for highly charged ion beams are put into operation for cyclotrons and atomic physics research. The development of high charge state ECR ion sources at IMP has progressed with a new magnetic field configuration, better condition for extraction of highly charged ions, high mirror magnetic field, large plasma volume, and special techniques to provide extra cold electrons. These techniques greatly enhance the production of highly charged ions from IMP ECR ion sources. So far more than 185u2002eμA of Ar11+ and 50u2002eμA of Xe26+ were produced by the IMP ECR ion sources. The metallic ion beam production was tested and the first beam 40Ca11+ was provided to the cyclotrons at IMP. The beam intensity of 40Ca11+ could reach 130u2002eμA. The next part of this arti...

Advancement of highly charged ion beam production by superconducting ECR ion source SECRAL (invited)

At Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS), the superconducting Electron Cyclotron Resonance (ECR) ion source SECRAL (Superconducting ECR ion source with Advanced design in Lanzhou) has been put into operation for about 10 years now. It has been the main working horse to deliver intense highly charged heavy ion beams for the accelerators. Since its first plasma at 18 GHz, R&D work towards more intense highly charged ion beam production as well as the beam quality investigation has never been stopped. When SECRAL was upgraded to its typical operation frequency 24 GHz, it had already showed its promising capacity of very intense highly charged ion beam production. And it has also provided the strong experimental support for the so called scaling laws of microwave frequency effect. However, compared to the microwave power heating efficiency at 18 GHz, 24 GHz microwave heating does not show the ω(2) scale at the same power level, which indicates that microwave power coupling at gyrotron frequency needs better understanding. In this paper, after a review of the operation status of SECRAL with regard to the beam availability and stability, the recent study of the extracted ion beam transverse coupling issues will be discussed, and the test results of the both TE01 and HE11 modes will be presented. A general comparison of the performance working with the two injection modes will be given, and a preliminary analysis will be introduced. The latest results of the production of very intense highly charged ion beams, such as 1.42 emA Ar(12+), 0.92 emA Xe(27+), and so on, will be presented.

Intense heavy ion beam production from IMP LECR3 and construction progress of a superconducting ECR ion source SECRAL

Intense heavy ion beams have been produced from IMP 14.5 GHz LECR3 by optimization of the ion source conditions and transmission efficiency. Highly charged stable beams, such as 325 eμA of Ar11+, 95 eμA of Xe26+, 7 eμA of Xe30+, 140 eμA of Fe13+, and 75 eμA of Ni12+, were obtained by 14.5 GHz rf power 800–1000 W. Furthermore, an advanced superconducting ECR ion source named SECRAL is being constructed. SECRAL is designed to operate at rf frequency 18–28 GHz with axial mirror magnetic fields 4.0 T at injection, 2.2 T at extraction, and sextupole field 2.0 T at the plasma chamber wall. The unique feature of this superconducting ECR source is that the sextupole is located outside of the three axial solenoid coils to reduce the interaction force and make the source more compact. Fabrications of the superconducting coils, cryostat, beam transmission line, and other components are almost completed. Tests of the superconducting magnet with sextupole and solenoid coils are under way.

A Progress Report of 320 kV Multi-discipline Research Platform for Highly Charged Ions

A dedicated platform for multi-disciplinary research with highly charged ions has been constructed, and an all-permanent magnet ECR ion source was built and installed in the beamline. Five experimental terminals are established for interdisciplinary Research. The high voltage supplied to the platform has reached 320 kV. The commissioning of the platform is successful, different ion beams have been provided for experimental studies, and the current status will be reported.

Note: investigation on the influences of gripping methods on elastic modulus by a miniature tensile device and in situ verification.

In this paper, by gripping the specimen on various positions, including the gripping section, stress concentration transition section, and gauge length section, theoretical analysis on the influences of gripping methods on tensile elastic modulus calculation was investigated with a group of equations. Then, an image-based displacement measurement system was implemented, and the experimental verification via in situ tensile testing was carried out to verify the feasibility of the theoretical analysis by a miniature tensile device integrated with a metallographic microscope. The stress-strain curves of 2026 aluminum alloy were also obtained by gripping the specimens on various positions to illustrate the influences of gripping methods. The influence of gripping methods on elongation measurement was also investigated. This paper showed a modular calculation method of elastic modulus for the tensile testing of typical plate specimens.

A low energy beam transport system for proton beam

A low energy beam transport (LEBT) system has been built for a compact pulsed hadron source (CPHS) at Tsinghua University in China. The LEBT, consisting of two solenoids and three short-drift sections, transports a pulsed proton beam of 60 mA of energy of 50 keV to the entrance of a radio frequency quadrupole (RFQ). Measurement has shown a normalized RMS beam emittance less than 0.2 π mm mrad at the end of the LEBT. Beam simulations were carried out to compare with the measurement and are in good agreement. Based on the successful CPHS LEBT development, a new LEBT for a China ADS projector has been designed. The features of the new design, including a beam chopper and beam simulations of the LEBT are presented and discussed along with CPHS LEBT development in this article.