Compact Plasma and Focused Ion Beams

85Plasma Production in Continuous-Mode Microwaves

Figure 5.11b shows the radial variation of T

e

and N

i

at P

in

= 180 W, given

the same conditions as Figure 5.8 [18]. The data are taken at the center (15 cm

from the entrance). T

e

shows a peak around 23 mm from the center, which

may be attributed to wave—plasma resonances, whereby the electrons gain

a large amount of energy in this region.

16

(a)

(b

)

28

24

20

16

12

8

4

MW

T

e

(eV)T

e

(eV)

T

e

(eV):

0.15 mTorr; 180 W

0.45 mTorr; 180 W

0.15 mTorr; 450 W

N

i

× 10

10

(cm

–3

):

N

i

(×10

10

cm

–3

)

N

i

(×10

10

cm

–3

)

0.15 mTorr; 180 W

0.45 mTorr; 180 W

0.15 mTorr; 450 W

14

12

10

8

6

4

036912 15 18 21 24 27 30

z (cm)

r (cm)

22

20

18

16

14

12

10

0.0 0.5 ...