magnetic fluctuations in high density pulsed plasma l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Magnetic Fluctuations In High Density Pulsed Plasma PowerPoint Presentation
Download Presentation
Magnetic Fluctuations In High Density Pulsed Plasma

Loading in 2 Seconds...

play fullscreen
1 / 18

Magnetic Fluctuations In High Density Pulsed Plasma - PowerPoint PPT Presentation


  • 239 Views
  • Uploaded on

Magnetic Fluctuations In High Density Pulsed Plasma. Sarvenaz Sarabipour Applied and Plasma Physics, The School of Physics, The University of Sydney, NSW, Australia, 2006. Outline. What is a plasma; Pulsed arc plasma source setup; Mirnov coils; Results; Conclusions and future work;.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Magnetic Fluctuations In High Density Pulsed Plasma' - rowena


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
magnetic fluctuations in high density pulsed plasma

Magnetic Fluctuations In High Density Pulsed Plasma

Sarvenaz Sarabipour

Applied and Plasma Physics, The School of Physics, The University of Sydney, NSW, Australia, 2006

outline
Outline
  • What is a plasma;
  • Pulsed arc plasma source setup;
  • Mirnov coils;
  • Results;
  • Conclusions and future work;
so what is a plasma
So What is a Plasma?!
  • The fourth state of matter.
  • 99% of visible matter in the Universe.
  • Examples are: Stellar interiors and atmospheres, nebulae, lightning, fluorescent tubes, plasma displays and fusion plasmas.
  • Definition: A form of quasi-neutral electrified gas with the atoms dissociated into positive ions and electrons.

Figure 1: The interior and atmosphereof the Sun is in the plasma state (x-ray view).

magnetically confined plasmas
Magnetically Confined Plasmas
  • Historically, plasma physics driven by fusion research, e.g. Tokamaks.
  • More recently, plasma processing uses plasmas for material applications.
  • Important plasma parameters: Toroidal B-field (BΦ), poloidal B-field (Bq ) and plasma current.

Figure 2: Example of a magnetically confined plasma in a Tokamak.

pulsed arc vacuum vessel
Pulsed Arc Vacuum Vessel
  • Consists of a half torus.
  • A magnetic plasma duct inside a quarter of the torus.
  • Major radius of the vessel is 0.44 m.
  • Duct radius is 0.072 m

Plasma source

Plasma Duct

Substrate

R.Davies 2003

Figure 3: The Experimental Setup

for the vessel.

pulsed cathodic arc

50 mm

Plasma duct

windings

Anode mouth

z

x

y

Pulsed Cathodic Arc
  • Very high density, up to 10²³ m-³.
  • Almost 100% ionised
  • Positively biasing the magnetic duct assists plasma transport

Figure 4:8 μs exposure image of plasma taken 300 μs after arc initiation (False colour image).

mirnov coils

Vertically Mounted

Mirnov Probe

Horizontally Mounted

Mirnov Probe

MirnovCoils.
  • Directly measure dBθ/dt & dBΦ/dt to detect magnetic fluctuations
  • An active integrator integrates the signal initiating form the probe (integrates over dB/dt to gives us BΦ & Bθ)

11 Turns,

Average diameter of ~ 8.37 mm

Figure 5: schematic of a Mirnov coil

Figure 6: Mirnov Probes Mounted

on the vessel.

location of mirnov probes in the vessel
Location of Mirnov Probes in the vessel

Mirnov 2

  • By locating Mirnov probes in this position (1cm inside the duct) the phase shift, rotation and rotation angle between BΦ & Bθhas been measured.

duct

Mirnov 1

Plasma

Mirnov 3

Figure 7: Schematic of the experimental setup for Mirnov probes.

scanning across the plasma
Scanning across The Plasma

Plasma

centre

Plasma

edge

No Plasma

mirnov probes detecting rotation
Mirnov Probes Detecting Rotation

Mirnov 2

  • Three Mirnov probes used to detect rotational behaviour of plasma.
  • Analysis in 200 - 300 μs time interval.
  • The top Mirnov coil consistently led the horizontal and bottom vertical Mirnovs → clockwise rotation.
  • Rotational velocities have been measured for various duct biases and duct (toroidal) magnetic field.

Mirnov 1

Plasma

Mirnov 3

Figure 8: Direction of Rotation of Bθ

discussion
Discussion.

Fluctuation frequency, [kHz]

  • Region of low rotational velocities in the 40 -60 V range and 15 mT.
  • Else where velocities up to 1000 krads-1! Consistent with literature.
  • Other measurements show:
    • Low oscillations at high magnetic field and high duct bias
    • Strong oscillations 30-50kHz at low magnetic field and high duct bias
slide15
We measured:

1)The physical dimensions of the plasma

2)The strength and fluctuations of the BΦ& Bθ fields.

● We found:

1) Plasma diameter ~ 4 cm.

2) The magnetic field oscillations rotate clockwise with velocities of 200-1000 krad.s-1

3) there are strong magnetic oscillations in the

plasma with an inverse relationship

between angular velocities and the

amplitude of the oscillations.

Project Summary

improvements further directions
Improvements & Further Directions
  • Using a series of Mirnov coils (e.g. 16) in a circle or semi-circle or placing the coils along the torus, to elucidate further the structure of magnetic fluctuations in the plasma.
  • Further experiments to determine whether the plasma is diamagnetic or paramagnetic.
acknowledgments
Acknowledgments

This project has been greatly assisted by:

The University of Sydney:

A/Prof. Rodney Cross,

Prof.Marcela Bilek,

Prof.David Mckenzie,

Dr.Richard Tarrant (supervisor),

Daniel Andruczyk (supervisor),

Luke Ryves,

John Pigott,

Phil Denniss,

The Australian National University:

Dr.Mattew Hole

Prof. Boyd Blackwell.