Hydrogen ion source with a cold magnetron cathode and magnetic plasma compression

A hydrogen ion source designed for the injector of a 16-MeV linear proton accelerator with an average beam current of ∼100 μA is presented. New design approaches allowing an improvement in the operating parameters of the ion source are proposed. The results of experimental tests of a source prototype operating in a pulsed mode with a repetition rate of 1–10 Hz and pulse duration of 100–600 μs are described.     

Extension of the gas-pressure operating range and increase in the lifetime of the plasma cathode grid of an ion source

A new scheme of a gas-discharge system is proposed for a basket-type ion source with a plasma cathode in which the electrons are emitted from the expanded anode part of a constricted hollow-cathode glow discharge bounded by a grid electrode. The modified electrode system of the ion source made it possible to enlarge the surface area of the plasma cathode grid and the aperture of its cells, thereby providing stable ion emission from the discharge plasma within a wide gas-pressure range and substantially (by one order of magnitude) increasing the grid lifetime. The operation of the plasma cathode in the free and forced emission modes is examined, and the energy efficiency of ion generation in the gas-discharge system under study is evaluated.     

Characteristics of an ion source with a plasma cathode and a multipole magnetic system for confining fast electrons

Parameters and ion-emission characteristics of the plasma generated in the anode stage of an ion source with a hollow glow-discharge plasma cathode are studied. To decrease the minimum operating gas pressure to 5×10³ Pa, a multipole magnetic system was installed on the surface of the hollow cathode and the peripheral magnetic field was enhanced in the anode stage of the source. The effect of the gas pressure, the plasma-cathode current, and the voltage between the electrodes of the anode stage on the value of the ion current extracted from the plasma is investigated. It is found that the size of the exit aperture of the hollow cathode substantially affects the efficiency of ion extraction. The potential (1–5 V) and the electron temperature (1–8 eV) of the anode-stage plasma are measured by the probe method. The conditions are determined that ensure the maximum ion-emission current from the plasma at low gas pressures.     

High-voltage pulsed discharge in an electron source with a plasma cathode

The nature of and mechanism for producing a high-voltage discharge in an electron source with a plasma cathode are investigated. The possibility of generating pulsed electron currents with an amplitude of 10³–10⁴ A and a length of 10^–6 sec is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 117–121, October, 1973.The authors thank B. M. Koval'chuk for help in developing the experimental arrangement and G. A. Mesyates for constant attention to the work and discussion of the results.     

Optimisation of cold cathode ion source model

This paper represents the results of the optimisation of cold cathode ion source model with 5 cm extraction aperture diameter. In this model, the glow discharge is utilised for generation of electrons in the cathode of the ion source. The various models with different lengths of cathode and anode are tested. The shortest model with 4.5 cm in length of cathode and anode each shows satisfactory operation and can be used in cases when the high values of extracted ion current are not required. The best model from the point of view of ion beam current value and efficiency of the discharge is the model with cathode length of 7 cm and anode length of 7 cm. In this case, the obtained maximum ion beam current is 110 mA when the discharge current is 1000 mA. In case when moderate values of extracted ion beam current are necessary, it is possible to operate the ion source even without the anode magnetic system.     

Ion source with a cold magnetron cathode and magnetic plasma compression

The operating principles, design, and characteristics of an ion source with a cold magnetron cathode and magnetic plasma compression are described. The source is intended for the injector of a linear proton accelerator.     

Self-oscillating mode of electron beam generation in a source with a grid plasma emitter

Plasma processes and electron beam generation in an electron source with a grid plasma cathode are investigated. Experiments are conducted under the conditions of efficient electron extraction and an intense counter ion flux, which break grid stabilization. It is shown that a rise in the gas pressure and in the emitting plasma potential leads to the plasma potential modulation in the frequency range 10⁴–10⁵ Hz. Under the self-oscillation conditions, an electron beam is obtained with a constant current of up to 16 A and an electron energy modulated up to 100% of the accelerating voltage level (100–300 V). An explanation is given for relaxation self-oscillations arising when the plasma potential grows and for the system’s inertial non-linearity arising when the plasma potential induced by the space charge of the counter ion flux lags behind the current of electron-beam-generated ions.     

Interaction of cathode plasma with the cathode surface in an electron source with explosive electron emission

The interaction of the plasma formed at emission centers of an electron source using explosive electron emission with the cathode surface is studied. It is found that the plasma flux does not flow around obstacles located in its path and is effectively deionized upon incidence on the wall.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 26–29, November, 1981.     

Beam-plasma mechanism for anode plasma generation in a low-pressure two-stage self-sustained discharge with a cold hollow cathode

Results are presented from experimental studies of the anode region of a low-pressure two-stage self-sustained discharge with a closed cold hollow cathode. It is shown that applying an external longitudinal magnetic field promotes the generation of a dense anode plasma, whereas the transverse field impedes this generation. It is established that the beam-plasma mechanism for plasma generation plays a dominant role in the anode region of the discharge. The geometry of the electrodes of the gas-discharge chamber is optimized.     

内表面栅极等离子体源离子注入TiN薄膜及其特性研究

阐述了栅极增强等离子体源离子注入（GEPSII）方法的基本思想.利用GEPSII方法在45号钢 基底上生成了金黄色氮化钛（TiN_x）膜.对不同条件下的TiN膜做电化学腐蚀，X PS，AES， XRD等分析.电化学腐蚀实验显示TiN薄膜改善了45号钢的耐腐蚀性能5—10倍，且在高气压下 效果更好.结构分析显示TiN膜含有TiO₂，TiN成分，主要沿（111）和（200）晶 向生长，深度分析显示膜的厚度只有二十几纳米，膜质地均匀且在基底有一定的嵌入深度. 关键词： 腐蚀 等离子体源离子注入 薄膜 氮化钛     

Generation of high-current electron beams by a hollow cathode with a ferroelectric plasma source

This paper presents results and analysis of an experimental investigation of the operation of a hollow cathode (HC) with an incorporated ferroelectric plasma source (FPS). It was shown that the use of FPS based on a BaTi solid solution allows one to ignite and to sustain a 10²-10³ A HC discharge with duration of 10^-3-10^-5 s at background pressure of 5 x 10^-3 Pa while keeping the HC design with small dimensions. It was found that the development of the HC discharge is accompanied by formation at the surface of the FPS of dense plasma which serves as a powerful (hundreds of kW) pulsed source of current carrying electrons. Parameters of the HC plasma (radial distribution of the plasma density and temperature and plasma potential) for different discharge current amplitudes and two types of FPS are presented. Application of the FPS as an electron source in a diode under an accelerating pulse 300 kV and pulse duration 400 ns showed that the latter operates in a plasma pre-filled mode with a current amplitude up to 1.6 kA. Parameters of the diode and electron beam for different experimental conditions are presented and discussed.Received: 10 April 2003, Published online: 12 August 2003PACS: 52.50.Dg Plasma sources - 29.25.Bx Electron sources - 52.25.Tx Emission, absorption, and scattering of particles     

Generation of a pulsed high-current low-energy beam in a plasma electron source with a self-heated cathode

The transition of a low-current discharge with a self-heated hollow cathode to a high-current discharge is studied, and stability conditions for the latter in the pulsed–periodic mode with a current of 0.1–1.0 kA, pulse width of 0.1–1.0 ms, and a pulse repetition rate of 0.1–1.0 kHz are determined. The thermal conditions of the hollow cathode are analyzed, and the conclusion is drawn that the emission current high density is due to pulsed self-heating of the cathode’s surface layer. Conditions for stable emission from a plasma cathode with a grid acting as a plasma boundary using such a discharge are found at low accelerating voltage (100–200 eV) and a gas pressure of 0.1–0.4 Pa. The density of the ion current from a plasma generated by a pulsed beam with a current of 100 A is found to reach 0.1 A/cm². Probe diagnostics data for the emitting and beam plasmas in the electron source are presented, and a mechanism behind the instability of electron emission from the plasma is suggested on their basis.     

Unstable plasma characteristics in mirror field electron cyclotron resonance microwave ion source

Electron cyclotron plasma reactor are prone to instabilities in specific input power [3–7] region (150–450 watts). In this region power absorption by gas molecules in the cavity is very poor and enhanced input power gets reflected substantially without increasing ion density. There are abrupt changes in plasma characteristics when input power was decreased from maximum to minimum, it was observed that reflected power changed from <2% to ∼50%. Minimum two jumps in reflected power were noticed in this specific power region and these appear to be highly sensitive to three stub tuner position in the waveguide for this particular input power zone. Unstable plasma region of this source is found to be dependent upon the magnetic field strength. Some changes in reflected power are also noticed with pressure, flow and bias and they are random in nature.     

Design of triode extraction system for a dual hollow cathode ion source

A triode extraction system is designed for a dual hollow cathode ion source being developed at the Institute of Heavy Ion Physics,Peking University.Basic parameters of the plasma are selected after examining the operation principle of the ion source,then the triode extraction system is designed and optimized by using software PBGUNS (for Particle Beam GUN Simulations).The physical design of the system is given in this paper.     

Design of triode extraction system for a dual hollow cathode ion source

A triode extraction system is designed for a dual hollow cathode ion source being developed at the Institute of Heavy Ion Physics, Peking University. Basic parameters of the plasma are selected after examining the operation principle of the ion source, then the triode extraction system is designed and optimized by using software PBGUNS (for Particle Beam GUN Simulations). The physical design of the system is given in this paper.     

Generation of a homogeneous plasma and wide ion beams in a penning system with a nonequipotential cathode

A study is made of the possibility of controlling the spatial distribution of the degree of ionization in a modified Penning cell with a cathode divided into several sections that are at different potentials. It is shown that an almost uniform plasma can be produced when applying an optimal potential of the control electrode. This enables the generation of wide ion beams in this system. An ion extraction efficiency of several tens of percent is achieved, which is substantially higher than in conventional ion sources.     

Influence of ion-beam plasma on ion extraction efficiency in a single-grid ion source

The influence of ion-beam plasma on ion extraction efficiency in a single-grid ICP ion source is researched. The single-grid ion source is considered as a system with two plasmas, ion-beam plasma and the source plasma, separated by an extraction grid. Results of experimental measurements of the potentials of the two plasmas and the ion beam current dependence on these potentials are presented. It is shown that the ion extraction efficiency depends equally on both the acceleration potential and on the potential of the ion-beam plasma. The obtained results demonstrate the key role of the ion-beam plasma in the ion source operation, which is important in technological applications and space thrusters.     

Current-voltage characteristics of a gas field ion source

Current-voltage characteristics of a gas field ion source (GFIS) have been measured for hydrogen and all rare gases. The parameter set included tip temperature, tip radius and gas temperature and pressure. This investigation has been made to get a complete overview of the field ion currents (FIC) and to estimate the maximum currents in a GFIS, which have been found to a few 100 nA. This estimate allows also a feasibility study of a GFIS, modified by a supertip, a small protuberance on the emitter surface.