Numerical Simulation Research of High Current Negative Ion Beam System

In order to assist design of high energy and high power neutral beam injector required for next generation fusion device, we establish the physics model and computer code for negative ion beam system numerical simulation according to the characteristic of high current negative ion beam     

Experiment and Operation of a LHCD—35kV／2.8MW／1000s High—Voltage Power Supply on HT—7 Tokamak

A-35kV/2.8MW/1000s high-voltage power supply(HVPS) for HT-7 superconducting tokamak has been built successfully.The HVPS is scheduled to run on a 2.45 GHz/1MW lower hybrid current drive(LHCD)^[1] system of HT-7 superoonducting tokamak before the set-up of HT-7 superconducting tokamak in 2003.The HVPS has a series of advantages such as good steady and dynamic response,logical computer program controlling the HVPS without and fault,operationa panel and experimental board for data acquisition.which both are grounded distinctively in a normative way to protec the main body of HVPS along with its attached equipments from dangers.Electric power cables and other control cables are disposed reasonably,to prevent singals from magnetic interference and ensure the precision of signal transfer.This paper involves the experiment and operation of a 35kV/2.8 MW/1000s HVPS^[2] for 2.45 GHz/1 MW LHCD system.The reliability and feasibility of the HVPS has been demonstrated in comparison with experimental results of original design and simulation data.     

Preliminary Research Results for the Generation and Diagnostics of High Power Ion Beams on FLASH II Accelerator

The preliminary experimental results of the generation and diagnostics of highpower ion beams on FLASH II accelerator are reported, The high-power ion beams presently are being produced in a pinched diode, The method for enhancing the ratio of ion to electron current is to increase the electron residing time by pinching the electron flow, Furthermore, electron beam pinching can be combined with electron reflexing to achieve ion beams with even higher efficiency and intensity. The anode plasma is generated by anode foil bombarded with electron and anode foil surface flashover. In recent experiments on FLASH II accelerator, ion beams have been produced with a current of 160 kA and an energy of 500 keV corresponding to an ion beam peak power of about 80 GW. The ion number and current of high power ion beams were determined by monitoring delayed radioactivity from nuclear reactions induced in a ^12C target by the proton beams, The prompt γ-rays and diode bremsstrahlung X-rays were measured with a PIN semi-conductor detector and a plastic scintillator detector, The current density distribution of ion beam were measured with a biased ion collector array. The ion beams were also recorded with a CR-39 detector.     

Study on the Variation of the Distant Crossing Rice by Ion Beam Implantation

In this paper, the following contents including the original receptor EI213 and other two control materials, RAPD polymorphism, photosynthetic efficiency, and the number of vascular bundles of the first internodes below the peduncle have been studied for the eight F7 transgenic lines obtained from ion beam implantation. The results showed that there was a significant variation in genomes of maize-rice line, compared with the receptor EI213, after the total exogenous maize DNA was introduced into EI213. The number of the vascular bundles of maize-rice progeny‘s lines was obviously much larger than those of the original receptor EI213 and other two controls GER-3 and MH63, and along with the photosynthetic efficiency of maize-rice progeny‘s lines being gone up. Moreover, the parenchyma cells around the vascular bundles of the transgenic lines became much larger in number and in size than those around the controls. All these indicated that the maize-rice progeny‘s lines are really different from and superior to the receptor and the controls. It is a novel and useful way to apply ion beam implantation in transferring DNA from C4 plant maize into C3 plant rice.     

Research on tune feedback of the Hefei Light Source Ⅱ based on machine learning

The theory of tune feedback correction and the principle of a feedback algorithm based on machine learning are introduced, with a focus on the application of lasso regression for tune feedback correction. Simulation verification and online feedback correction results are presented. The results show that, after applying machine learning, the feedback accuracy of the tune feedback system was higher, and the betatron tune stability was further improved.     

Simulation of the Effects of Several Factors on Arc Plasma Behavior in Low Voltage Circuit Breaker

Taking into account the properties of the arc plasma and the electromagnetic, heat and radiative phenomena, commercial computational fluid dynamics software PHOENICS has been adapted and modified to develop the three-dimensional magneto-hydrodynamic （MHD） model of arc in a low voltage circuit breaker. The effects of the arc ignition location, venting size and gassing material on arc behavior have been investigated. The analysis of the results show that the arc velocity accelerates with the increase in the distance between arc ignition location and of the venting size, and the existence of the gassing material is beneficial to improving the arc voltage and reducing the arc temperature.     

Measurement of Negative Ion Current of ^180HfF5^- as a Function of the Ratio of HfF4 to Ag

In Accelerator mass spectrometry （AMS） measurement, it usually need mix metal powder into samples. During ^182Hf measurement, usually we mix HfF4 with certain silver powder. As we found the negative ion current of ^180HfF5^- changes when different proportion of Ag＋HfF4 samples were used. In measurement of ^182Hf we need as larger ^180HfF5^- ion current as possible, so in this work we studied the negative ion current of ^180HfF5^- with different mass ration of Ag to HfF4 samples.     

Measurement of Negative Ion Current of ~(180)HfF_5~-as a Function of the Ratio of HfF_4 to Ag

In Accelerator mass spectrometry (AMS) measurement, it usually need mix metal powder into samples. During 182Hf measurement, usually we mix HfF4 with certain silver powder. As we found the     

Filling Factor Impacts on Beam Halo-chaos Control’s Effects in K-V Distribution in Periodic Focusing Beam Transport Network

The effect of the filling factor on beam halo-chaos control in K-V distribution was systematicallystudied. By numerical simulation, the filling factor takes value from 0.75 to 0.99 in which the control effect is better, it enlarges the filling factor valu…     

Experimental Observation of the Pulsed High Pressure Gas Puffing on HL-2A Tokamak

The pulse propagations of both the electron temperature and the electron density have been observed during pulse-modulated molecular beam injection experiments on HL-2A. The propagation depth of the cold pulse in the low field side is much longer than that in the high field side. The cold pulses cannot propagate to the plasma center from either the low field side or the high field side. The electron temperature in the plasma center does not change during MBI, but the electron density pulse perturbations can be observed in the plasma center.     

Possibility of long-term nuclear power development based on today’s technology

The possibility of long-term nuclear power development with a uranium fuel cycle based on ²³⁸U burnup and todays industrial technology is investigated. It is shown that such development is possible with fast reactors, including with sodium coolant. In this case, incomplete fuel reprocessing is admissable in a closed fuel cycle employing a pyroelectrochemical technology, which allows some fission products and actinides to be present in the fresh fuel prepared for reloading after reprocessing. These fission products and actinides can be burned in a reactor, thereby decreasing the quantity of radioactive wastes compared with the complete reprocessing with chemical separation of the fuel elements and decreasing the radiation load on the environment.Translated from Atomnaya Ènergiya, Vol. 97, No. 4, pp. 252–260, October, 2004.     

Effectiveness analysis of the reactor operator’s adviser computer code

Testing of the computer code Reactor Operator’s Adviser on the No. 3 unit of the Leningradskaya nuclear power plant showed that the recommendations given in the code increase substantially (by a factor of 1.2) the minimum margin to the P2 level for the adjusted signal from the in-reactor detectors along the radius and decrease the maximum temperature of the graphite masonry by 12°C and the maximum nonuniformity factor of the energy release distribution by 3%. Operation for 3.5 h using the Reactor Operator’s Adviser code recommendations maintained the operational parameters characterizing the energy release distribution along the core radius and height within acceptable limits.     

Estimation of the resident’s additional dose in bone-coal mining areas of the five provinces

1 Introduction In the National Investigation of Natural Radioac-tive Levels (abbreviated as “investigation of levels” hereinbelow) during 1983 to 1990, it is found that the specific activities of radionuclides in bone-coal are relatively high. The increase of radioactive level in the environment and the rise of the public accepted dose might be caused by some artificial activities, which include mainly mining and utilizing spontaneously bone-coal by local peasants, producing bone-coal cind…     

Research on the Distant Hyvbrids of Wheat Obtained via Low—Energy Ion—Beam Implantation

The whole DNA of soybean was implanted into four varieties of wheat of Zhougyu 5,Huaiyin 9628,Wenyou 1,Jimai 5 respectively via ion-beam mediation.There were 5 plants obtained whose protein content was higher than 18.5%,the highest one was 21.44%,There were 3 plants obtained whose protein content was lower than 11.5%,the lowest one was 10.96%.We can see that the whole DNA of soybean transformed into wheat via ion beam implantation can induce the increase in wheat protein content dramatically.The result also shows that the transformation efficiency of different gene types of wheat receptor varies greatly that the implanting time has a certain effect on the efficiency of transformation.