I= STUDY OF PLASMA ELECTRON TEMPERATURE OF THE PINCH FILAMINT AND X-RAY EMISSION FROM THE ANODE TIP IN A LOW ENERGY (2.3 kJ) MATHER TYPE PLASMA FOCUS
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Title of Thesis
STUDY OF PLASMA ELECTRON TEMPERATURE OF THE PINCH FILAMINT AND X-RAY EMISSION FROM THE ANODE TIP IN A LOW ENERGY (2.3 kJ) MATHER TYPE PLASMA FOCUS

Author(s)
Muhammad Shafiq
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University
Session
2003
Subject
Physics
Number of Pages
106
Keywords (Extracted from title, table of contents and abstract of thesis)
plasma electron temperature, pinch filamint, plasma focus, fluence anisotropy, vacuum spark, z-pinch, k-series line radiation emission

Abstract
X- ray emission from a low energy (2.3 kJ) plasma focus energized by a 32 JlF capacitor charged at 12 KeV is investigated two fold: i) The continuum! bremsstrahlung X-rays are analyzed to obtain information about the electron plasma temperature in the pinch filament, and the X-radiation are employed for backlighting of a test of object (copper mesh), ii) X-ray emission in different energy windows, and its fluence anisotropy is investigated.

To determine the plasma electron temperature by continuum X-ray analysis, Co is selected as a filter, which discriminates the line radiation from the back ground impurities like carbon, nitrogen and oxygen, or the radiation from plasma focus electrodes, which are commonly made of copper. It is found to be a good choice to diagnose 0.5-7 KeV hot plasma in a device like plasma focus. The electron temperature at different deuterium filling pressures is found to vary from 2 - 5 KeV. It is about 2.5 KeV at 0.5 mbar. With increase in pressure, the temperature increases and attains its maximum value of 5 KeV at 2.5 mbar, and then gradually decreases to 2 KeV at 4.5 mbar. For argon plasma, the electron temperature at different filling pressures is found to vary from 1.5-7.0 KeV. It is about 5 KeV at 0.25 mbar, which increases to about 7 KeV at 0.5 mbar and then decreases to 1.5 ke V at 2.25 mbar.

When the device is operated with argon as the filling gas, the bulk of X-radiation emission is observed from the region close to the anode tip. These radiation are found suitable for backlighting in Al (1-1.56 KeV) and Ti (2.9-4.96 ke V) energy transmission bands. A simple technique to measure the fluence anisotropy of X-rays emitted from a source is presented. The simplicity of the technique and response curves of the photographic film along with corresponding filters enable one to readily use the same for diagnostic purposes in different sources like plasma focus, vacuum spark, Z-pinch and laser produced plasmas. As an application example, the technique is employed to measure fluence anisotropy of X-ray emission in a low energy plasma focus operated with hydrogen. It is found that with increase in hydrogen filling pressure, the anisotropy of X-ray emission is enhanced, although the total emission is lowered. It reveals that at lower filling pressure of 0.75 mbar, the X-ray emission is dominant due to interaction of energetic electrons in the current sheath, whereas at 2.5 mbar, the contribution of energetic electron beam is much higher.

K-series line radiation emission of Mo and Cu is studied with hydrogen as the filling gas. The measurable X-ray flux is observed in the pressure range of 0.5-3.5 mbar. Mo and Cu K-line radiation emission has the highest values of about 0.05 J/sr and 0.17 J/sr respectively at a filling pressure of 2.0 mbar. The corresponding efficiencies are 0.03% and 0.09% respectively. Total X-ray emission and efficiency in 47t-geometry are also obtained with values 4.12 J and 0.2% at 2.0 mbar. The emission in different energy windows, by employing high Z inserts (Pb, W or Mo) at the anode tip is investigated also. The X-ray flux from the focus region is observed measurable within the pressure range 0.25-3.5 mbar of hydrogen. The maximum emission in 47t-geometry is found 29.4:t0.2, 3.43:t0.05 and 4.00:t0.02 joules with Pb, Wand Mo inserted anodes respectively and corresponding wall plug efficiencies for X-ray generation are 1.28%, 0.15% and 0.2%. The X-ray emission is found dominantly as a result of electron beam activity at the anode tip that is confirmed by the images recorded by the pinhole camera.

Download Full Thesis
2455.15 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
277.04 KB
2 1 Introduction 1
202.71 KB
  1.1 X-Ray Emission From Plasma Focus 2
  1.2 Electron Temperature Of The Focus Plasma 7
  1.3 Layout Of The Thesis 11
  1.4 References 12
3 2 Experimental Setup And Diagnostics 14
321.08 KB
  2.1 Dense Plasma Focus System 14
  2.2 Current And Voltage Measurements 21
  2.3 X-Ray Detection And Analysis System 30
  2.4 Calculation Of X-Ray Yield 45
  2.5 References 46
4 3 Measurement Of Hot Plasma Electron Temperature 48
542.99 KB
  3.1 Selection Of Appropriate Filters 49
  3.2 Evaluation Of Plasma Electron Temperature 55
5 4 Study Of X-Ray Emission From Focus Plasma 65
1048.74 KB
  4.1 X-Ray Fluence Anisotropy 68
  4.2 Mo K-Series Line Radiation 74
  4.3 X-Ray Emission In Different Energy Windows 81
  4.4 References 95
6 5 Conclusions And Suggestions For The Future Work 98
244.98 KB