ion energy distributions from a permanent magnet helicon thruster
Download
Skip this Video
Download Presentation
Ion Energy Distributions from a Permanent-Magnet Helicon Thruster

Loading in 2 Seconds...

play fullscreen
1 / 31

Ion Energy Distributions from a Permanent-Magnet Helicon Thruster - PowerPoint PPT Presentation


  • 101 Views
  • Uploaded on

Ion Energy Distributions from a Permanent-Magnet Helicon Thruster. Francis F. Chen, UCLA. Low Temperature Plasma Physics Webinar, January 17, 2014. The “New Stubby” helicon source. Note “skirt”. Antenna: 1 turn at 27 MHz, 3 turns at 13 MHz. Aluminum top plate.

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 ' Ion Energy Distributions from a Permanent-Magnet Helicon Thruster ' - maj


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
ion energy distributions from a permanent magnet helicon thruster

Ion Energy Distributions from a Permanent-Magnet Helicon Thruster

Francis F. Chen, UCLA

Low Temperature Plasma Physics Webinar, January 17, 2014

slide2

The “New Stubby” helicon source

Note “skirt”

Antenna: 1 turn at 27 MHz, 3 turns at 13 MHz.

Aluminum top plate

slide4

The B-field is from a Neodymium magnet

The magnet is 5” OD, 3” ID, and 1” thick. We use the almost uniform field below the stagnation point.

slide5

The tube was designed with the HELIC code

D. Arnush, Role of Trivelpiece-Gould Waves in Antenna Helicon Wave Coupling, Phys. Plasmas 7, 3042 (2000).

slide6

Sample loading curves from HELIC

R should be > 1W at operating density

slide12

Downstream density vs B and Prf

This shows that only 30 - 60 G is necessary.

slide13

Only an off-the-shelf magnet is needed

The magnet is 4” OD,

2” ID, and 1/2” thick

The plasma potential is set by grounding the top plate.

slide16

The SEMion ion energy analyzer

by Impedans, Ltd., Ireland

4” diam x 1 cm thick

slide17

The sensor height can be varied continuously

When the sensor is too close to the discharge, it forms an endplate, and the discharge is double-ended.

We know that the discharge is affected because the tuning is changed.

slide20

Double-layer thrusters

A review of recent laboratory double layer experiments

Christine Charles, Plasma Sources Sci. Technol. 16 (2007) R1–R25

slide21

Cause and location of the “double layer”

F.F. Chen, Phys. Plasmas 13, 034502 (2006)

Maxwellian electrons

Bohm sheath criterion

A sheath must form here

Single layer forms where r has increased 28%

slide22

Ion energy distribution functions (IEDF)

Expect about 5 the KTe of 1.5-2 eV

slide24

IEDFs vs distance from source

close to tube

further downstream

There is no sign of a double layer jump.

This is probably because the sensor changes the effective length of the discharge.

slide28

Can we increase the ion drift speed?

Yes! Applying +24V to top plate

increases vi by ~16eV, while

applying -24V reduces vi by ~6eV.

The voltage is applied with a Pb-acid battery from an electric scooter.

slide30

Summary

A small helicon discharge was developed

using a permanent magnet for the B-field.

 Ions are ejected with a drift velocity of

about 5KTe, measured with a retarding-

field energy analyzer.

 The ion drift can be increased by biasing

the top plate of the discharge relative to

nearby grounded surfaces.

 This device could be developed into a

spacecraft thruster.

ad