摘要:

A new facility using 6 MeV/nheavy‐ion beams is described along with preliminary results of its applications to biophysical investigations. The beams are obtained at the terminal of the injector linac installed in the heavy‐ion medical accelerator in Chiba. Various ion species (He–Xe) having different charge states are accelerated to the same velocity, which is suitable for comparing the charge effects of heavy ions. An attempt has been made for investigations of the track structure by using pBR322 plasmid DNA and spores as targets. Newly constructed equipment with the molecular beam source (H2O) placed on this beam line is also described. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146672

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A universal pocket PIG ion source with a permanent magnet has been developed by our institute. Usually the source can produce single and multiple charged ions of gas or metal elements. At 20–30 kV extraction voltage, milliamperes of gas ions, and tens of &mgr;A of metal ions can be extracted with less than 50 W of discharge power consumption. And negative ions of some elements with larger electron affinity can be extracted directly from the source. Thus far, using LaB6as a cathode, more than 50 &mgr;A of H−, about 1.4 mA of O−, and 1.8 mA of F−ions in total beam have been extracted at 15–20 kV extraction voltage. The power consumptions are less than 40, 50, and 100 W, respectively. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146673

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A side extraction PIG ion source with a permanent magnet is introduced, which can be used not only for producing miliampere positive ion beams, but also for direct extraction of negative ions of some elements with larger electron affinity. So far H, O, and F negative ions have been extracted from the source. At −15 kV extraction voltage, O−ion beams of 130 &mgr;A and a F−ion beam of 75 &mgr;A are extracted, and the discharge power consumption is 110 and 280 W, respectively. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146674

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In this paper we report the results of production of ions of solids from the PIG source with an additional anode and solid material feed by cathode sputtering. The investigations were performed at the test bench and at the U‐400 cyclotron. Two versions of the ion source with different dispositions of the sputtering electrode were studied. In the first version the sputtering electrode is introduced into the discharge chamber through the wall opposite to the emission slit, the second version has lateral disposition of the sputtering electrode. The influence of the potential of an additional anode on the total extracted current and charge state distribution was studied at the test bench for both versions. The results of the test of the ion source with lateral disposition of the sputtering electrode at the U‐400 cyclotron are reported. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146675

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

High charge state ion beams are commonly used in atomic and nuclear physics experiments. Multiply charged ions are normally produced in an ECR or in an EBIS. Multicusp generators can confine primary electrons very efficiently. Therefore, the electrical and gas efficiencies of these devices are high. Since the magnetic cusp fields are localized near the chamber wall, large volumes of uniform and high density plasmas can be obtained at low pressure, conditions favorable for the formation of multiply charged state ions. Attempts have been made at LBNL to generate multiply charged ion beams by employing a 25‐cm diam by 25‐cm long multicusp source. Experimental results demonstrated that charge states as high as 7+ can be obtained with argon or xenon plasmas. Multiply charged metallic ions such as tungsten and titanium have also been successfully formed in the multicusp source by evaporation and sputtering processes. In order to extend the charge state to higher values, a novel technique of injecting high energy electrons into the source plasma is proposed. If this is successful, the multicusp source will become very useful for radioactive beam accelerators, ion implantation, and nuclear physics applications. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146676

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A surface ionization type dual‐ion source (DIS) developed for ionic crystalline samples such as alkali halides (MX) consists of (1) a sample plate (F1, ∼0.02 cm2) heated up to ∼1000 K to produce primary ion (M+or X−) by dissociative self‐surface ionization of MX deposited on F1, (2) a second filament (F2) kept at 1260 K to produce secondary ion (M+) by molecular beam surface ionization of the neutral molecule (MX0) desorbing from F1and (3) a grid (G) mounted between F1and F2to retard the primary and secondary ions. These ions are independently extracted efficiently and collected separately without using any separator other than G. Our DIS is free from background ions due to residual gases, easy in operation, simple in structure and small in size (∼2 cm3) but quite useful for kinetic studies of ionic and neutral desorption from MX and also for generating monochromatic and stable dual‐ion beams (∼1 pA) from MX (∼1 &mgr;g) deposited on F1. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146677

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The effects of source plasma parameters and space charge neutralization on energy spread of very low energy and high perveance ion beam have been studied experimentally. Plasma parameters of a bucket source were changed by shorting an arc chamber and a positive electrode (a plasma electrode) to deteriorate electron confinement. Although the change of plasma potential reflected the beam energy and the change of energy spread was observed, the relation between the plasma parameters and energy spread is unclear. Space charge neutralization of the ion beam by supplying thermal electron and increasing gas pressure in beam transport region showed reduction of the energy spread. This result suggests that the space charge effects of the ion beam plays an important role in energy broadening. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146678

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In order to produce high brightness beam at energies below 100 eV, the effects of high deceleration voltage in a triode extraction system and plasma potential have been studied. Although the application of high deceleration voltage caused beam spreading, beam brightness was increased at least up to accel–decel ratio of 80. It is found that the reduction of sheath potential of the source plasma caused the increase in beam brightness under high deceleration voltage condition. In particular, it is desirable to reduce sheath potential at the energy below 50 eV because this potential is comparable to external applied acceleration voltage. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146679

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Results which focus on comparing operation in hydrogen and deuterium are presented. Measurements of plasma parameters, including electron density, electron temperature, electron energy distribution function and extracted negative ion current, have been made in the source and extractor regions of an electron beam excited negative ion source. For the same operating conditions, negative ion current is found to be higher in deuterium than in hydrogen. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146680

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The recent development of various types of ion sources and their application in China is reviewed. Emphasis is given to new improvements of the electron cyclotron resonance ion source, MEVVA ion source, electron beam evaporation metal ion source, compact multicusp ion source, as well as compact negative ion sources with permanent magnets. Some of the new proposals are also presented. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146681

出版商:AIP    

年代:1996

数据来源: AIP