Temperature diagnostics of ECR plasma by measurement of electron bremsstrahlung

The x-ray bremsstrahlung spectrum emitted by the electron population in a 14.5 GHz ECR plasma source has been measured using a NaI(Tl) detector, and hence the electron temperature of the higher energy electron population in the plasma has been determined. The x-ray spectra for Ne and Ar gases have been systematically studied as a function of inlet gas pressure from 7 × 10(-7) mbar to 7 × 10(-5) mbar and for input microwave power ～1 W to ～300 W. At the highest input power and optimum pressure conditions, the end point bremsstrahlung energies are seen to reach ～700 keV. The estimated electron temperatures (T(e)) were found to be in the range 20 keV-80 keV. The T(e) is found to be peaking at a pressure of 1 × 10(-5) mbar for both gases. The T(e) is seen to increase with increasing input power in the intermediate power region, i.e., between 100 and 200 W, but shows different behaviour for different gases in the low and high power regions. Both gases show very weak dependence of electron temperature on inlet gas pressure, but the trends in each gas are different.     

Experimental investigations of silicon tetrafluoride decomposition in ECR discharge plasma

The results of first experiments on the investigation of plasma of electron cyclotron resonance (ECR) discharge, sustained by CW radiation of technological gyrotron with frequency 24 GHz are considered. The parameters of nitrogen plasma of ECR discharge in magnetic field up to 1 T were investigated by Langmuir probe in the pressure range 10(-4)-10(-2) mbar under different values of microwave power. Depending on gas pressure and power of microwave radiation, the typical temperature and density of electrons could attain values of 1-5 eV and 10(11)-10(12) cm(-3), respectively. The prospects for using of ECR discharge for plasma chemical decomposition of silicon tetrafluoride (SiF(4)) have been experimentally demonstrated. Plasma was created from SiF(4) and hydrogen (H(2)) gas mixture and heated by microwave radiation in ECR conditions. Using the method of mass-spectrometry analysis of the gas at the outlet from the reactor and the weighting method, the content of the resultants of SiF(4) decomposition as a function of process parameters was investigated. It was shown that SiF(4) decomposition degree strongly depends on the microwave power, gas pressure in the reactor, gas flow rates, and can attain the value of 50%. The possible applications of PECVD method based on ECR discharge for production of isotopically pure elements with high deposition rate are discussed.     

Features of semiplanotron surface plasma sources

Features of the semiplanotron surface plasma sources (SPS) with cesiation used for high efficient negative ion beam production from first development to modern condition are considered. Design features of semiplanotrons SPS with cylindrical and spherical geometric focusing and the features of the negative ion production in the semiplanotrons are reviewed. Several versions of semiplanotrons with efficiency up to 0.1 A of H(-) per kW of discharge power are discussed. Modifications of the semiplanotrons for dc operation and for heavy negative ion production are reviewed.     

ECR等离子源静电探针自动监测系统

ECR等离子源主要由电源系统、抽气系统、供气系统、真空室等设备组成,对于研究型设备,还包括测控部分.传统的测控系统对系统设备大多采用单台测控,人工调节,这样系统效率比较低.该文采用模拟开关切换8路静电探针得到不同位置的等离子体参数,经电荷放大器对弱信号进行放大后显示.该方法在实际使用中取得了较好的效果.     

A collimator for hot plasma x-ray diagnostics in ion sources

We present a collimator configuration for measuring energy resolved x-ray plasma volume bremsstrahlung emitted, e.g., by an ECRIS. Special attention we paid to shielding the detector against interfering Compton scattered radiation and wall bremsstrahlung stemming from the collimator entrance aperture. We estimate the efficiency for shielding of Compton scattered radiation at least attainable by this arrangement.     

等离子体发射光谱法测定食品级磷酸三钙中铬的含量

采用等离子体发射光谱法测定了食品级磷酸三钙中的铬含量。该方法具有操作简单、快速、准确度,精密度高,检出限低等优点。回收率为92.86%,9次测定的RSD为4.54%。     

Subcutoff microwave driven plasma ion sources for multielemental focused ion beam systems

A compact microwave driven plasma ion source for focused ion beam applications has been developed. Several gas species have been experimented including argon, krypton, and hydrogen. The plasma, confined by a minimum B multicusp magnetic field, has good radial and axial uniformity. The octupole multicusp configuration shows a superior performance in terms of plasma density (~1.3 x 10(11) cm(-3)) and electron temperature (7-15 eV) at a power density of 5-10 Wcm(2). Ion current densities ranging from a few hundreds to over 1000 mA/cm(2) have been obtained with different plasma electrode apertures. The ion source will be combined with electrostatic Einzel lenses and should be capable of producing multielemental focused ion beams for nanostructuring and implantations. The initial simulation results for the focused beams have been presented.     

Status and special features of the Atomki ECR ion source

The ECR ion source has been operating in ATOMKI (Debrecen) since 1996. During the past 15 years lots of minor and numerous major technical modifications have been carried out on the ECRIS. Many of these changes aimed the increasing of beams charge, intensity, and the widening of the ion choice. Another group of the modifications were performed to develop special, non-standard operation modes or to produce peculiar plasmas and beams.     

Off-line ionization tests using the surface and the plasma ion sources of the SPES project

The development of new target ion source systems for the selective production of exotic species (SPES) facility is currently in progress at Legnaro National Laboratories. In this context, the study of ion sources and their performance in terms of ionization efficiency and transversal emittance is a crucial point in order to maximize the available yields, particularly for short-lived isotopes. In this work, preliminary off-line ionization efficiency and emittance measurements for the SPES surface and plasma ion sources are presented. The plasma source emittance measurements are supported by dedicated numerical calculations.     

ECR离子源高真空微调针阀控制系统

本论文介绍所研制的适用于30kV高压端的ECR离子源高真空微调针阀控制系统。系统中被控对象是位于ECR源上的高真空微调针阀,它与地面之间有30kV的电位差。系统的特点是使用光路实现高压绝缘和信息传输。这为解决位于ECR离子源高压端器件的控制问题提出新思路。     

The mass separation and collection of ions having large angular and energy spreads emitted from pulsed plasma sources

A novel method for isotope separation is presented. In the proposed system, the ions are generated by a pulsed ion source having large angular and energy spread, then move through a field-free region to an electrodynamic reflecting filter, where the ions are separated according to their charge-to-mass (q/m) ratio. The collection angle is nearly 4π sr. A numerical example for separating hydrogen isotopes is presented.     

ECR Plasma CVD淀积介质膜的工艺模拟

以实验数据为基础,运用人工神经网络方法,建立了电子回旋共振等离子体化学气相沉积（ＥＣＲ Ｐｌａｓｍ ａ ＣＶＤ）淀积硅的氮、氧化物介质膜折射率ｎ 与气流配比Ｑ（Ｎ２）／Ｑ（ＳｉＨ４）和Ｑ（Ｏ２）／Ｑ（ＳｉＨ４）关系的数学模型,此模型在给定气流配比Ｑ（Ｎ２ ）／Ｑ（ＳｉＨ４）和Ｑ（Ｏ２）／Ｑ（ＳｉＨ４）时所预测的成膜折射率跟实验值符合得很好,该数学模型为ＥＣＲ Ｐｌａｓｍ ａ ＣＶＤ淀积全介质光学膜的工艺模拟打下坚实的基础。     

电感耦合等离子体原子发射光谱法测定钎剂中硼钠钙

介绍了采用电感耦合等离子体原子发射光谱法(ICP-AES)测定钎剂中硼钠钙的方法,进行了钎剂样品的溶解试验,用一定比例盐酸、硝酸混合酸采用微波消解方法溶解,考察了钎剂基体和共存元素对待测元素的光谱干扰情况,确定了各待测元素分析线分别为B 182.578 nm、Na 588.995 nm、Ca 393.366 nm。进行了仪器工作参数选择试验,确定了仪器最佳工作条件,通过加入内标钇控制测量波动,实现了用电感耦合等离子体原子发射光谱法测定钎剂中硼钠钙的含量。进行了加入回收试验,回收率在98~105%之间,相对标准偏差小于1%。     

Intense beams from gases generated by a permanent magnet ECR ion source at PKU

An electron cyclotron resonance (ECR) ion source is designed for the production of high-current ion beams of various gaseous elements. At the Peking University (PKU), the primary study is focused on developing suitable permanent magnet ECR ion sources (PMECRs) for separated function radio frequency quadrupole (SFRFQ) accelerator and for Peking University Neutron Imaging Facility. Recently, other kinds of high-intensity ion beams are required for new acceleration structure demonstration, simulation of fusion reactor material irradiation, aviation bearing modification, and other applications. So we expanded the ion beam category from O(+), H(+), and D(+) to N(+), Ar(+), and He(+). Up to now, about 120 mA of H(+), 83 mA of D(+), 50 mA of O(+), 63 mA of N(+), 70 mA of Ar(+), and 65 mA of He(+) extracted at 50 kV through a φ 6 mm aperture were produced by the PMECRs at PKU. Their rms emittances are less than 0.2 π?mm?mrad. Tungsten samples were irradiated by H(+) or He(+) beam extracted from this ion source and H∕He holes and bubbles have been observed on the samples. A method to produce a high intensity H∕He mixed beam to study synergistic effect is developed for nuclear material irradiation. To design a He(+) beam injector for coupled radio frequency quadruple and SFRFQ cavity, He(+) beam transmission experiments were carried out on PKU low energy beam transport test bench and the transmission was less than 50%. It indicated that some electrode modifications must be done to decrease the divergence of He(+) beam.     

Towards a better comprehension of plasma formation and heating in high performances electron cyclotron resonance ion sources (invited)

Further improvements of electron cyclotron resonance ion sources (ECRIS) output currents and average charge state require a deep understanding of electron and ion dynamics in the plasma. This paper will discuss the most recent advances about modeling of non-classical evidences like the sensitivity of electron energy distribution function to the magnetic field detuning, the influence of plasma turbulences on electron heating and ion confinement, the coupling between electron and ion dynamics. All these issues have in common the non-homogeneous distribution of the plasma inside the source: the abrupt density drop at the resonance layer regulates the heating regimes (from collective to turbulent), the beam formation mechanism and emittance. Possible means to boost the performances of future ECRIS will be proposed. In particular, the use of Bernstein waves, in preliminary experiments performed at Laboratori Nazionali del Sud (LNS) on MDIS (microwave discharge ion sources)-type sources, has permitted to sustain largely overdense plasmas enhancing the warm electron temperature, which will make possible in principle the construction of sources for high intensity multicharged ions beams with simplified magnetic structures.     

Work function measurements during plasma exposition at conditions relevant in negative ion sources for the ITER neutral beam injection

Cesium seeded sources for surface generated negative hydrogen ions are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER. The stability and delivered current density depend highly on the work function during vacuum and plasma phases of the ion source. One of the most important quantities that affect the source performance is the work function. A modified photocurrent method was developed to measure the temporal behavior of the work function during and after cesium evaporation. The investigation of cesium exposed Mo and MoLa samples under ITER negative hydrogen ion based neutral beam injection relevant surface and plasma conditions showed the influence of impurities which result in a fast degradation when the plasma exposure or the cesium flux onto the sample is stopped. A minimum work function close to that of bulk cesium was obtained under the influence of the plasma exposition, while a significantly higher work function was observed under ITER-like vacuum conditions.     

高锰酸钾滴定法测定钙片中的钙含量

[目的]为了准确测定钙片中钙的含量。[方法]建立了高锰酸钾容量滴定法测定钙片中钙含量的方法。[结果]该法是样品经湿法消化后,在酸性溶液中,钙与草酸生成草酸钙沉淀。沉淀经洗涤后,加入硫酸溶解,把草酸游离出来,然后在70～80℃条件下,用高锰酸钾标准溶液滴定与钙等当量结合的钙含量。测定结果的回收率（R）在98．40％～109．74％。[结论]用高锰酸钾滴定法测定钙片中的钙含量,简单、快捷、准确、干扰小。