scholarly journals Development of Ion Current Prediction Model in Alpha Radioactivity Measnrement using Ionized Air Transportation

2005 ◽  
Vol 4 (1) ◽  
pp. 7-15 ◽  
Author(s):  
Susumu NAITO ◽  
Akira SANO ◽  
Mikio IZUMI ◽  
Shigeru KANEMOTO ◽  
Yasuaki MIYAMOTO ◽  
...  
Keyword(s):  
Prediction Model ◽  
Air Transportation ◽  
Ion Current ◽  
Alpha Radioactivity ◽  
Ionized Air

Alpha Radioactivity Monitor Using Ionized Air Transportation for Large Size Uranium Waste: Part 1—Large Measurement Chamber and Evaluation of Detection Performance

2010 ◽  
Author(s):  
Susumu Naito ◽  
Shuji Yamamoto ◽  
Mikio Izumi ◽  
Yosuke Hirata ◽  
Yukio Yoshimura ◽  
...  
Keyword(s):  
Maximum Size ◽  
Air Transportation ◽  
Detection Performance ◽  
Practical Applications ◽  
Large Size ◽  
Large Measurement ◽  
Alpha Radioactivity ◽  
Clearance Level ◽  
Ionized Air ◽  
Measurement Chamber

We present an ionized air transportation type alpha radioactivity monitor to efficiently perform the clearance level inspection for large size uranium waste and its detection performance. In previous work, we developed a prototype monitor with an about 1000 mm cubic measurement chamber to measure the cut waste. However, in a survey of target waste, we found that it is desired to measure not only the cut waste but also the lengthy waste such as uncut cylinders. Therefore, we developed an alpha radioactivity monitor with a long and large measurement chamber (effective sizes: 500 mm x900 mm x3200 mm) for long and large cylindrically-shaped waste (maximum size: 300 mm in diameter and 3000 mm in length, weight: 10 to 200 kg). We aimed <1000 Bq as the target value of Alpha radioactivity Detection Limit (ADL), which is one-tenth of the clearance level (1 Bq/g) for 10 kg waste. The issue to size up the measurement chamber was to suppress the reduction in sensitivity of alpha radioactivity. To overcome this, we enhanced an air fan power and optimized an ion sensor design. Using this monitor, we measured and evaluated ADLs for several cases supposing the practical applications (long cylinders with a smooth surface, bump, or concavity and convexity, and pipes with several small diameters). The resulting ALD ranged from 60 Bq to 120 Bq and sufficiently satisfied the target ALD (<1000 Bq). In conclusion, this monitor has sufficient performance for the clearance level inspection for large uranium waste.

Alpha Radioactivity Monitor Using Ionized Air Transport Technology for Large Size Uranium Waste: Part 2—Simulation Model Reinforcement for Practical Apparatus Design

2010 ◽  
Author(s):  
Takatoshi Asada ◽  
Yosuke Hirata ◽  
Susumu Naito ◽  
Mikio Izumi ◽  
Yukio Yoshimura
Keyword(s):  
Ion Transport ◽  
Simulation Model ◽  
Cfd Simulation ◽  
Transport Model ◽  
Model Simulation ◽  
Ion Density ◽  
Transport Simulation ◽  
Simulation Results ◽  
Alpha Radioactivity ◽  
Ionized Air

In alpha radioactivity measurement using ionized air transportation (AMAT), conversion from ion currents to radioactivity accurate is required. An ion transport simulation provides ways of complementarily determining conversion factors. We have developed an ion transport simulation model. Simulation results were compared with experiments with air speeds, faster than 1 m/s, achieving good agreement. In a practical AMAT apparatus, the air-flow at the alpha source may be slower than 1 m/s, and ion loss is likely to be large. Reinforcement of the ion transport model to cover the lower air speed region is effective. Ions are generated by an alpha particle in a very thin column. Since the ion density at this temporal stage is high, the recombination loss, proportional to the square of ion density, is dominant within a few milli-seconds. The spatial and temporal scales of this columnar recombination are too small for CFD simulation. We solve an ion transport equation during the period of columnar recombination with diffusion and recombination terms and incorporated the relation between ion loss and turbulent parameters into CFD. Using this model, simulations have been done for various air speeds and targets. Those for simulation results agree with experiments, showing improvement of simulation accuracy.

scholarly journals Innovative Alpha Radioactivity Monitor for Clearance Level Inspection Based on Ionized Air Transport Technology

2008 ◽  
Vol 2 (2) ◽  
pp. 561-572
Author(s):  
Yosuke HIRATA ◽  
Katsuhiko NAKAHARA ◽  
Akira SANO ◽  
Mitsuyoshi SATO ◽  
Yoshio AOYAMA ◽  
...  
Keyword(s):  
Air Transport ◽  
Alpha Radioactivity ◽  
Clearance Level ◽  
Ionized Air

Microscale Ion-Driven Air Flow Over a Flat Plate

Volume 4 ◽  
2004 ◽  
Author(s):  
Daniel J. Schlitz ◽  
Suresh V. Garimella ◽  
T. S. Fisher
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Air Flow ◽  
Electronics Cooling ◽  
Heat Sinks ◽  
Ion Current ◽  
Electrode Potentials ◽  
Bulk Motion ◽  
Generation Region ◽  
Ionized Air

A microscale air pump concept that uses ionized air molecules under the influence of an electric field is studied. The method employed is an extension of the corona wind concept and is referred to here as microscale ion-driven air flow. The two major differences are that the ions are created in a distinct generation region, and are then put in motion by a traveling electric field in the pumping region. The ions create bulk motion of the air because of ion drag. One application of this technology involves generation of air flow through microchannels or other micro-featured surfaces to create compact, high flux heat sinks for electronics cooling. This work focuses on the ion pumping aspect of the technology. A device was constructed and tested with an array of micro-fabricated electrodes that generate strong electric fields in the air. The electrode potentials were cycled to impart a unidirectional force to the ions over meso-scale distances. The microscale ion-driven air flow concept was demonstrated by electrical means, through the measurement of the ion current produced. A set of designed experiments were conducted that showed the electrode potential to be the most significant factor for sustaining an ion current. A two-dimensional numerical model of the ion motion has been developed and validated against the experimental results. The model describes the time-dependent ion flow induced over an array of evenly spaced microscale electrodes that are used to generate a translating electric field.

Quantitative Measurements on the Ion Etching of TMV

1973 ◽  
Vol 31 ◽  
pp. 336-337
Author(s):  
Irwin Bendet ◽  
Nabil Rizk
Keyword(s):  
Electron Microscope ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Ion Current ◽  
Beam Diameter ◽  
Ion Etching ◽  
Preliminary Results ◽  
Quantitative Measurements ◽  
Monitoring Devices

Preliminary results reported last year on the ion etching of tobacco mosaic virus indicated that the diameter of the virus decreased more rapidly at 10KV than at 5KV, perhaps reaching a constant value before disappearing completely.In order to follow the effects of ion etching on TMV more quantitatively we have designed and built a second apparatus (Fig. 1), which incorporates monitoring devices for measuring ion current and vacuum as well as accelerating voltage. In addition, the beam diameter has been increased to approximately 1 cm., so that ten electron microscope grids can be exposed to the beam simultaneously.

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