Intense beam production with ECR ion sources

Electron cyclotron resonance ion sources are now able to attain a beam current as high as some milliamperes, which until a few years ago was obtained only for pulsed laser ion sources with a much higher emittance and energy spread, by keeping also the possibility to produce high charge states close to electron beam ion sources, at much higher intensity. They usually operate at frequencies up to 18 GHz, but now many sources are able to operate or will be able, at 28 GHz frequency or more, with plasma density of the order of 10¹³ cm^?3, much higher than any other source of the previous generation. The state-of-the-art technique will be described along with the major characteristics of the upcoming sources.     

ECR离子源外电子注入技术研究

使用电子枪对ECR（Electron Cyclotron Resonance）等离子体注入外电子束是继铝衬弧腔、偏压盘之后,对等离子体电子的额外补充的又一种手段,通过向弧腔中注入一定能量与流强的电子束,以期提高引出束流的流强与电荷态。但由于该方法可控参数繁多,经验积累与报道资料都很少,且设计与操作远不如偏压盘等手段简便,故一直未能得到深入研究。通过以三维仿真软件CST粒子工作室对注入到弧腔电子束的运动轨迹的模拟结果为依据、以18 GHz ECR蒸发冷却源为平台,进行了ECR等离子体注入电子束的实验,结果表明:在一定实验条件下,当注入电子束能量超过1 800 eV时,会产生一种引出的离子束流的激增现象。在这个现象中,脉冲与直流的流强均比未注入电子时要高,束流电荷态向高价方向移动,且可通过控制实验条件来控制这种现象。最后对于这种电子并未通过共振面,却能起到提高电荷态与流强的作用进行了分析与讨论,并认为该现象在改善直流束与脉冲束性能的方面都有着积极的意义。The injection of the electron beam into the ECR (Electron Cyclotron Resonance)plasma by electron gun is a new method for the additional supplementary of the plasma electron, following the aluminum chamber wall and the bias plate, we are expecting for the higher current and charge state of the ion beam with it. However, because of the controllable parameter's variety, the lack of the accumulation of experience and data, and the shortage of convenience in designing and experimental practicing compared by biased disk and other means,it has always not been intensively studied. In this article, we take the 18 GHz ECR Ion Source using evaporative cooling technique as experimental platform, do the experiment of injecting electron into ECR plasma base on the simulation result of the electron beam's path in ECR's chamber by the 3D simulation software CST the particle studio. It shows that a pulsing leap of the current of the extracting ion beam appears when the injecting electron's energy is above 1 800 eV. In the mean time, the top of the pulse and the average current of the ion beam rises, the ionization state moves to a higher level. This phenomenon can be turned on and off by controlling the experimental condition. At the last part of the article, we discuss this improvement of the current and charge state of the ion beam despite of the position's missing between the injection of electron beam and the resonance surface, and hold the opinion that this phenomenon is positive to both pulsed and direct beam.     

The Cubic-Two-State Equation of State: Cross-associating mixtures and Monte Carlo study of self-associating prototypes

A new equation of state for associating fluids has recently been presented by Medeiros and Tellez-Arredondo, the Cubic-Two-State Equation of State (CTS EoS) [Ind. Eng. Chem. Res. 47 (2008) 5723]. This equation arises from the coupling of the Soave–Redlich–Kwong EoS (SRK) with an association term from a two-state association model. The CTS EoS is polynomial in volume and it is able to describe vapor pressures and molar volume of associating fluids such as water, alcohol and phenol, among others. The equation is also able to describe the liquid–vapor equilibria of their mixtures with alkanes. In this paper, the physical and thermodynamic foundations of the CTS EoS are further investigated. In order to verify its applicability for cross-associating systems, the equation was employed in the prediction of phase equilibria behavior of binary alcohol–alcohol and water–alcohol mixtures. Very good agreement between predictions and experimental phase equilibria data was obtained with very simple combining rules and only one adjustable binary parameter. No additional parameters were necessary to describe ternary systems. With the purpose of checking the model's hypothesis and limitations, the two-state association term was coupled with the hard sphere Carnahan–Starling EoS, forming the CS-TS equation and the association characteristic parameters were determined theoretically for prototype association fluids. Monte Carlo NPT simulations of such fluids were performed and the results were compared with the equation's predictions. The CS-TS was able to describe qualitatively the pvT$pvT$ behavior of the prototype; nevertheless, it is not as accurate as those predictions obtained from the combination CS with Wertheim's association term. It seems that, when adjusting parameters of the CTS EoS to real substances, the discrepancies between the predicted and the real association contribution are dissipated among other adjustable parameters, specially on the dispersive term of the SRK equation. Finally, it is shown that CTS EoS isotherms can only have one or three real bigger roots than the co-volume for positive pressures, similar to cubic equations of state, and then it has the desirable form to describe vapor–liquid phase equilibria of associating compounds mixtures.     

ANL的2Q-LEBT装置的进展报告

The concept for a 2 charge state injector for a"RIA type"accelerator has been presented.Progress toward an operational prototype 2Q-LEBT system at Argonne National Laboratory(ANL)is under way. The existing BIE 100 all permanent magnet ECR has been placed on a high voltage platform capable of a combined>100kV with q/m separation at ground level.Remote control of the devices on the platform has been implemented.Other components of the facility are currently being tested.The components of an achromatic bending system are currently being procured.This paper will present recent work at the facility as well as preliminary development of solid materials using the BIE 100.     

微波技术对ECR离子源性能的影响

The coupling between microwave generators and ECR ion sources(ECRIS)is a key point for the design of the new generation ECRIS as well as for the optimization of the existing ones.The electromagnetic characterization of the plasma chamber where the ionization phenomena take place is a fundamental starting point to understand and model such process.In such effort the complex structures of the injection and extraction flanges together with the large dimensions of the chamber and the high frequencies that are typically used make impossible an analytical solution and also create great difficulties in the modelling even with state-of- art electromagnetic simulators(CST,HFSS),In the following paper the results of some numerical calculations for the optimum plasma chamber excitation will be presented along with the experimental measurements carried out with the SERSE ion source at INFN-LNS.A campaign of measurements is also planned to further investigate the microwave coupling and the mode excitation,which determines the efficiency of the ECR plasma heating.     

NSCL从ECR离子源向CCF注入的离子束流动力学研究

The Coupled Cyclotron Facility (CCF) has been operating at the NSCL since 2001,providing up to 160MeV/u heavy ion beams for nuclear physics experiments.Recent steps,particularly the improvement of the ECR-to-K500 injection line,were taken to improve the CCF performance.For that purpose an off-line ECR source,ARTEMIS-B,was built and used to investigate the impact on beam brightness under various source operating conditions,different initial focusing systems and current analysis dipole.Beam dynamics simulations including space-charge and 3D electrostatic field effects were performed and beam diagnostics including emittance scanner were used,leading to a better understanding of the CCF beam injection process. New initial electrostatic focusing elements such as a large-bore quadrupole triplet and a quadrupole double- doublet with compensating octupole were tested,and a new beam tuning procedure was established to improve the beam brightness for the CCF.Following these efforts,a significant increase of primary beam power out of the CCF has been achieved.     

SECRAL等离子体中EUV光功率的产生

The high power EUV source is one of key issues in the development of EUV lithography which is considered to be the most promising technology among the next generation lithography.However neither DPP nor LPP seems to meet the requirements of the commercial high-volume product.Insufficiency of DPP and LPP motivate the investigation of other means to produce the EUV radiation required in lithography.ECR plasma seems to be one of the alternatives.In order to investigate the feasibility of ECR plasma as a EUV light source,the EUV power emitted by SECRAL was measured.A EUV power of 1.03W in 4~ sr solid angle was obtained when 2000W 18GHz rf power was launched,and the corresponding CE was 0.5%.Considering that SECRAL is designed to produce very high charge state ions,this very preliminary result is inspiring. Room-temperature ECR plasma and Sn plasma are both in the planned schedule.     

一台2.45GHz强流中子源

A 2.45GHz microwave-driven ion source is being used to provide 40mA of deuterium ion beam (peak current) for an RFQ accelerator as part of a neutron source system.We have also designed a 60kV electrostatic LEBT using computer simulations.In our experiment,we measured the hydrogen and deuterium ion beam currents as functions of discharge power,gas flow,and magnetic field strength.The required beam current was obtained using leas than 700W of net microwave power with a gas flow of less than 1.5sccm.From the rise time data,it was determined that in order to obtain a high percentage of atomic ions in the beam, the beam extraction should start after 1ms of switching on the microwave power.At steady state,the proton fraction was above 90%.     

Reusable thin film photocatalyst of Fe‐doped TiO2 deposited by ECR plasma

The paper presents an improved method of depositing nanocrystalline thin films of Fe‐doped TiO₂ to be used as a reusable cyclic photocatalyst for degrading the organic pollutants. The technique of electron cyclotron resonance plasma‐enhanced chemical vapor deposition was employed with titanium tetra‐isopropoxide (C₁₂H₂₈O₄Ti) and ferrocene (C₁₀H₁₀Fe) as precursors of Ti and Fe, respectively. Optical emission spectroscopy was used to identify the reactive species, to determine the electron temperature and the ion density during deposition. The films were characterized using optical absorption and photoluminescence spectra, whereas the morphological analysis was carried out with scanning electron microscopy. Strong adhesion of the deposited films with the substrate ruled out any possibility of TiO₂ particles being leached out. It was confirmed by observing the degradation rate of the same film repeatedly. Cyclic use of the film for the catalytic reactions thus makes the process much user friendly for the water treatment. Copyright © 2014 John Wiley & Sons, Ltd.