袖珍永磁端引出PIG离子源

介绍了一个袖珍永磁端引出ＰＩＧ离子源，它可用于产生各种气体的单电荷和多电荷离子，在不大于３０Ｗ的放电功率下，可引出ｍＡ级离子流，源的阴极寿命大于２００ｈ。     

Multiply charged ions from solids produced under energetic, heavy ion impact

Multiply charged ions from solids under energetic, heavy ion impact have been observed and compared with those from gas atoms and molecules. It is found that the production of multiply charge ions from most metallic solids is significantly reduced, compared to that from gas targets, meanwhile metallic ions from solids of oxided materials seem to be produced in a way similar to that from gas targets. It is also pointed out that impurities adsorbed on surface play an important role in the production of ions from metallic surfaces. Possible applications of energetic, heavy ion bombardment to study of desorption from solid surfaces are discussed.     

VUV-Spectroscopy of Multiply Charged Ion Source-Plasmas

The ion charge state distribution (CSD) in a multiply charged ion source- (MCIS-) plasma can be determined from the spectrum of resonance transitions of excited neutral and ionised plasma particles. The principle of this method, which for noble gas ions involves vacuum-ultraviolet spectroscopy, is described and first measurements for a DUOPLASMATRON-ion source operated with He and Ar are presented.     

The enhanced aerosol deposition by bipolar corona discharge arrays

The corona discharges provide an efficient way to induce precipitation or eliminate fog by increasing ion density in the open air.In this paper,one bipolar corona discharge array (positive and negative high voltage coupled simultaneously) which can generate high densities of positive and negative ions is developed.The comparison between bipolar corona discharge array and unipolar corona discharge array (positive or negative coupled only) indicates that bipolar corona discharge array can generate ～3 times higher ion density than unipolar corona discharge array.More charged aerosols are produced through collisions between ions and aerosols.The collision rate between aerosols is increased substantially by the attractive forces between positively and negatively charged aerosols.The deposition of aerosols induced by bipolar discharges is 25.7％higher than that of unipolar discharges at the humidity super-saturation condition.Therefore,the bipolar corona discharge system is a new option for the large scale ion sources used for artificial weather modification.     

Numerical simulation program of multicomponent ion beam transport from ECR ion source

In order to research multi-component ion beam transport process and improve transport efficiency, a special simulating program for ECR beam is becoming more and more necessary. We have developed a program written by Visual Basic to be dedicated to numerical simulation of the highly charged ion beam and to optimization of beam dynamics in transport line. In the program the exchange of electrons between highly charged ions and low charged ions or neutral atoms (residual gas in transport line) is taken into account, adopting classical molecular over-barrier model and Monte Carlo method, so the code can easily give the change of charge state distribution along the transmission line. The main advantage of the code is the ability to simultaneously simulate a large quantity of ions with different masses and charge states, and particularly, to simulate the loss of highly charged ions and the increase of low charged ions due to electron exchange in the whole transport process. Some simulations have been done to study the transmission line of LECR3 which is an ECR ion source for highly charged ion beam at IMP. Compared with experimental results, the simulations are considered to be successful.     

Using a current method for measuring ion-induced electron emission from LiF

The interaction of ions with an insulating substrate leads to surface charging. For intense ion beams these charges are not sufficiently fast removed between successive ion impact events. As a result the trajectories of the incident beam and the electron emission yield may be altered in a hardly predictable way. We demonstrate, that by heating an alkali-halide sample to a sufficiently high temperature, this macroscopic charging can be avoided and a simple current method can be used to study electron emission from such a surface. Measured electron emission yields from a LiF(1 0 0) single crystal due to impact of singly and multiply charged heavy noble gas ions (argon and xenon) are presented. For argon projectiles our results compare well with previous data, which were obtained using a more sophisticated electron statistics method and six orders of magnitude less intense ion beams.     

A Penning Ion Source for Multiply Charged Ions

The ion source described in this contribution allows the production of considerable ion beam intensities of highly charged ions. The electron density is increased by an additional electron gun. The decrease-of the ratio of neighbouring charge states is similar to the decrease of the ratio of the ionization cross sections by electron impact from which one event ionization processes are assumed to be of major importance in the performance of this source.     

State promotion and neutralization оf ions near metal surface

When a multiply charged ion with charge Z approaches the metal surface, a dipole is formed by the multiply charged ion and the charge induced in the metal. The states for such a dipole are promoted into continuum with decreasing ion-surface distance and cross the states formed from metal atom. The model proposed explains the dominant population of deep bound states in collisions considered.     

Transient Behavior of Negative Hydrogen Ion Extraction from Plasma

For plasma source,the extraction of negative ions is quite diferent from that of positive ions.To understand the efect of extraction field on plasma,the time-dependent behavior of negative hydrogen ion extraction from a negative ion source has been studied by particle-in-cell simulation in the collisionless limit.The simulations have shown that,due to the diference in dynamics between electrons and ions,the imbalance of the numbers of charged particles occurs in the source,results in the broadening of plasma sheath and the great increase of plasma potential.The resultant high sheath field and the ambipolar electric field in plasma make the negatively charged particles congregate inside the sheath and move toward the extraction outlet.The emission area of negative ions is much smaller than that of the extraction aperture,which is in sharp contrast to the case of positive ion extraction.     

The Electron Beam Ion Source and Some Possibilities for Improvement

Considering basic properties of the EBIS, as vacuum requirements, ion yield, and emittance, it is pointed out, that the EBIS - as proposed by Donets - is restricted in priciple to a poor yield of highly charged ions, To overcome this, a concept for a "dynamic containment" is presented. This means, that the axial ion movement between first ionization and the extraction is delayed in order to give the necessary containment time at CW-operation. Realization seems to be possible by the partly permeable mirrors, produced by the axial alternating magnetic field of opposing permanent ring magnets, which also provide for electron focusing, considerable reduction of vacuum requirements, and saving of power consumption.     

Use of the Hot-Electron Mirror Machine Interem as a High-Z Ion Source

Production of the high-Z charge states in helium, nitrogen, and argon has been measured in the INTEREM device at the Oak Ridge National Laboratory. The INTEREM device contains a hot electron (~500 keV) plasma trapped in a minimum B geometry. The device is of interest because its parameters, electron density and energy, and ion lifetime are consistent with those required for the production of highly charged ions. Ion charge and ion energy spectra were measured independently using an einzel lens type energy analyzer combined with a quadrupole mass filter. For helium, most of the ions were doubly charged under proper operating conditions. For nitrogen, we found the ion yield to be peaked at Q = 4, and under these conditions the yield at Q = 6 was down by a factor of about 20. Energy distribution curves for different charge states show interesting features, from which important information may be inferred about the plasma in INTEREM. Although discrepancies exist in the ion yields we conclude that an INTEREM-like device employing a minimum B geometry and electron cyclotron resonance heating may be expected to be a good high-Z ion source.     

Single electron capture by state-selected multiply charged Arq+ ions (q = 3,4)

State-selective single electron capture by multiply charged Ar^q+ ions (q = 3, 4) has been studied in rare gas targets with the aid of double translational spectroscopy. The energy gain spectra have been measured using different projectile beams, either extracted from an electron beam ion source or produced by electron capture reactions in an additional preparation cell. The influence of metastable projectile states as well as the reaction channel identification in complex systems are discussed.     

镍海绵浸渍氧化物阴极在北京质子加速器中的应用和研究

描述了北京质子直线加速器（ＢＰＬ）双等离子体源中使用的一种低加热功率镍海绵浸渍氧化物阴极的结构、底金属表面的海绵化处理以及浸渍涂料的制备方法。介绍了该阴极的激活方法和实验结果。讨论了影响氧化物阴极使用寿命的主要因素。该阴极的使用寿命已达２１１０ｈ，可供引出脉冲束流２００ｍＡ。     

Characteristics of Positive Ions in the Sheath Region of Magnetized Collisional Electronegative Discharges

A hydrodynamic model is used to investigate the characteristics of positive ions in the sheath region of a low-pressure magnetized electronegative discharge. Positive ions are modeled as a cold fluid, while the electron and negative ion density distributions obey the Boltzmann distribution with two different temperatures. By taking into account the ion-neutral collision effect in the sheath region and assuming that the momentum transfer cross section has a power law dependence on the velocity of positive ions, the sheath formation criterion （modified Bohm＇s criterion） is derived and it is shown that there are specified maximum and minimum limits for the ion Mach number M. Considering these two limits of M, the behaviors of electrostatic potential, charged particle density distributions and positive ion velocities in the sheath region are studied for different values of ion-neutral collision frequency.     

Production of intense highly charged ion beams by IMP 14.5GHz electron cyclotron resonance ion source

A new 14.5GHz Electron Cyclotron Resonance(ECR) ion source has been constructed over the last two years.The source was designed and tested by making use of the latest results from ECR ion source development ,such as high mirror magnetic filed,large plasma volume,and biased probe.140μA of O^7 ,185μA of Ar^11 and 50 μA of Xe^26 could be produced with a RF power of 800W, The intense beams of highly charged metallic ions are produced by means of the method of a metal evaporation oven and volatile compound throuth axial access,The test results are 130μA of Ca^11 ,70μA of Ca^12 and 65 μA of Fe^10 ,The ion source has been put into operation for the cyclotron at the Institute of Moderm Physics(IMP).     

A Study of a Duoplasmatron Ion Source with an Expansion Cup

This work describes a study of the Duoplasmatron ion source for the purpose of investigating the conditions necessary to improve its performance. First a general review is made of theoretical considerations involved in the source's plasma mechanism and the geometry of the extraction system. Then the experimental work deals with the arc discharge characteristics as well as the source's performance when the beam is extracted with a simple Pierce extracting electrode. Through an invar anode insert a 70 mA was obtained at 35 kV. The main improvement was then due to beam extraction from an expansion cup which rendered a 300 mA beam at a lower voltage of 18 kV. The use of different anode materials has indicated the influence of magnetic field penetration on plasma focusing within the expansion cup. A beam current reaching 1 ampere was noticed when a non-magnetic anode was used.     

High efficiency metal ion source

A double hollow cathode ion source can produce a high amount and high current density of metal ions (Mo) by using a new sputtering discharge mode of hollow cathode discharge. It is evident that the new sputtering discharge mode occurs under suitable conditions of the diameter of the second hollow cathode and the magnetic field. At a sputter voltage of 600 V and magnetic field of 1.0 kG, the metal ion beam ratio of reaches 50%.     

Recent Developments in Accelerator Based Atomic Physics

Much progress toward a detailed understanding of atomic collision phenomena and atomic structure has recently been made with the aid of accelerated ion beams. Beam foil Lamb shift measurements and the possible observation of spontaneously created positrons from quasi-superheavy atoms give promise for critical tests of QED. The mechanisms of innershell ionization and charge transfer in ion atom collisions have been intensively investigated and the results have brought together the various approaches - Coulomb excitation and MO treatments for these processes. That violent collisions at high energies can cause multiple ionization of the target atom has been known for some time. However, only recently have theoretical treatments been able to predict, e.g., the degree of L shell ionization accompanying K shell ionization. The highly charged ions formed in these collisions have themselves come under intensive investigation and are used for the study of the structure and collision physics of multiply charged species. Electron-Ion collision studies have also been started and initial results on dielectronic recombination are reported.     

Survey of Multicharged Ion Sources Physics and Some Extraction Problems

A review is given of fundamental processes leading to the production of multicharged ions by electron-atom collision : direct electron ejection, Auger process, electron shake-off. Results concerning ionization crosssections by electron impact are discussed. Some approximate methods allowing to a good knowledge of the ionic population in different types of ion sources (hot plasma devices, laser ion source, electron bombardment and discharge sources). At the end, some problems concerning emittance and brightness of heavy multicharged ion sources are examined.