Design of the discharge system with electron oscillations in the emission region for the positive ion source was studied. Realization of the conditions for electron oscillation in the emission region of the electrode system allowed to increase the energy efficiency of a glow discharge. Obtained characteristics of the discharge with electron oscillation in the emission region of the discharge chamber allow to conclude about possibility of its application in the positive ion source operating at low pressure in the discharge chamber.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/911

Baturin, V.A.

Litvinov, P.A.

SocioEconomic Challenges Journal (Sumy State University)

 
 
 
J. Nano- Electron. Phys. 
1 (2009) No2, P. 48-51 
?2009 SumDU 
(Sumy State University) 
 
 
48 
PACS numbers: 82.33.Xj, 29.25.Ni 
 
DISCHARGE SYSTEM WITH ELECTRON OSCILLATIONS IN THE 
EMISSION REGION FOR THE POSITIVE ION SOURCE 
 
P.A. Litvinov, V.A. Baturin 
 
Institute of Applied Physics, National Academy of Sciences of Ukraine, 
58, Petropavlivs’ka Str., 40030, Sumy, Ukraine 
E-mail: baturin@ipflab.sumy.ua 
 
Design of the discharge system with electron oscillations in the emission region for 
the positive ion source was studied. Realization of the conditions for electron 
oscillation in the emission region of the electrode system allowed to increase the 
energy efficiency of a glow discharge. Obtained characteristics of the discharge with 
electron oscillation in the emission region of the discharge chamber allow to conclude 
about possibility of its application in the positive ion source operating at low pressure 
in the discharge chamber. 
 
Keywords: DISCHARGE CHAMBER, GLOW DISCHARGE, POSITIVE IONS, ION 
BEAM, ION SOURCE 
 
(Received 25 August 2009, in final form 18 September 2009) 
 
1. INTRODUCTION 
 
Glow discharges, because of the burning stability at current densities on the 
cathode up to tens A/cm2 and the simplicity of their technical realization, 
are attractive for application in plasma sources of charged particles. The 
main problem arising from such application of glow discharges consists in 
the necessity of the gas pressure decrease in the discharge chamber below 
10 Pa for providing the electric strength of acceleration gap. The solution of 
this problem is achieved using the specific form of glow discharge optimized 
for the negative ion generation [1]. 
 But the radial distribution of the plasma density in the emission region 
of this discharge system was specially made in such a way that the minimal 
plasma density was on the axis. Physical ideas about the processes, which 
take place in similar discharge system, are considered in [2], and the 
discharge system itself is schematically represented in Fig. 1. In the case of 
the positive ion extraction such distribution of the plasma density is not the 
optimal one. 
 
2. EXPERIMENTAL RESULTS AND DISCUSSION 
 
To produce the positive ion source the discharge system developed earlier for 
the negative ion source was changed. In the present work we discuss the 
results of the first experimental investigations of the modified electrode 
system for the positive ion generation. Structural diagram of this discharge 
system is represented in Fig. 2. 
 Plasma is generated in the double-chamber (chambers 5 and 6) inverse 
gas magnetron, where both the magnetic and the electrostatic fast electron 
confinement occur. As the result, their staying time in the magnetron 
chambers is large and they can make a sufficient number of ionizations for 
 
 
 
 DISCHARGE SYSTEM WITH ELECTRON OSCILLATIONS IN … 49 
 
 
 
keeping the discharge. Both discharge chambers are hooked up parallel to 
the one power source. Potential difference between the electrodes of the 
discharge system is assigned by the automated displacement on resistances, 
as shown in Fig. 2. 
 
 
 
 
 
 
 
 
 
Fig. 2 – Design of the discharge 
system with electron oscillation in 
the emission region 
 
 
 
 
 
 
 
Fig. 1 – Design of the electrode 
system and the axial distribution 
of magnetic strength in a pole gap: 
1, 2 – anode; 3, 4 – cathode; 5, 6 –
chambers of high and low pressure, 
respectively; 7, 9 – contracting annular 
channels; 8 – emission chamber; 
10 – biased anode; 11 – emission 
electrode; 12 – lower pole; 13 –
magnetic circuit; 14, 15, 16, 17 –
Sm-Co5 magnets 
L, mm 
180 mm 
B
, 
T
 ?
1
0
–
4
 
1
3
0
 m
m
 
g
as
 
g
as
 
 
 
 
50 P.A. LITVINOV, V.A. BATURIN  
 
 
 The main differences of the present electrode system from the one used 
by us in the negative ion source and described in [2] consist in the following: 
1. Emission electrode 11 is under the cathode potential, and the mode of 
electron oscillation in the emission chamber 8 is realized there, that gives  
a possibility to increase the energy efficiency during the positive ion 
extraction from plasma. 
2. Geometry of the biased anode 10 is modified, and being of such design it 
is the main anode (MA) of the discharge system. 
 Known, that in glow discharges with electron oscillation there is a group 
of fast electrons, and though their fraction is not large, but precisely their 
contribution to ionization is the main one [3]. Thus, one can expect the 
increase of the discharge efficiency. 
 In Fig. 3 we present the diagram of the stretched on MA-to-the total 
discharge current ratio k ? IMA/Id versus the total discharge current Id for 
the discharge with electron oscillation (Fig. 2), and the dependence of the 
stretched on emission electrode (EE)-to-the total discharge current ratio 
k ? IEE/Id versus Id for the discharge without electron oscillation (Fig. 1). 
 
1,0 1,2 1,4 1,6 1,8 2,0
0,60
0,65
0,70
0,75
0,80
0,85
0,90
??????????????
?????????????k
I ?, A
 
Fig. 3 – Dependences of the current ratio k versus the total discharge current 
 
 The working pressure was P ? 3?10–2 Pa for the both cases. As seen from 
the diagram, discharge in the electrode system with electron oscillation in 
emission plasma has the greater energy efficiency. 
 In Table 1 we represent values of the discharge voltages with electron 
oscillation Uosc and without it Uw.osc at two values of the discharge current 
and working pressure in the discharge chamber 3?10–2 Pa and 2?10–2 Pa. 
 Analysis of the Table 1 shows that the values of voltage drop on the 
discharge interval in the modified electrode system have lower magnitudes 
in comparison with the analogue both at different values of the working 
pressure and at different values of the discharge current. This fact also 
confirms the great energy efficiency of the electrode system with electron 
oscillation, based on which it is proposed to produce the positive ion source. 
 
k 
 
Id, A 
 
without oscillation 
 with oscillation 
 
 
 
 DISCHARGE SYSTEM WITH ELECTRON OSCILLATIONS IN … 51 
 
 
 
Table 1 – Comparative characteristics of the discharge voltages with and 
without electron oscillation 
 
Uosc, V Uw.osc, V Id, À Ð, Pa 
380 405 1,0 
390 420 1,5 3?10
–2 
395 420 1,0 
410 435 1,5 2?10
–2 
 
 We also have to note, that in some experiments we have observed the 
strong increase of the voltage drop on the discharge interval 8 at the 
pressure decrease lower than the certain critical value. A glow discharge was 
almost transformed into the high-voltage form. The same phenomenon takes 
place when the gap length between the cathode end-plane 4 and the electrode 
10 increases. These two causes can be used in future for the maintenance of 
the high-voltage form of a glow discharge, for example, during the 
generation of double-charged ions. 
 Increase of the plasma density on the axis of the emission region of the 
electrode system can be achieved due to magnetic compression as it has done 
in [4]. The required configuration of magnetic field lines along the system 
can be obtained varying the number and the disposition of the beam-
positioning magnets along the magnetic circuit 13. Later on it is necessary 
to use the water-cooling of the anode 10 as well. 
 
3. CONCLUSIONS 
 
Thus, based on the prior experimental results obtained we can conclude the 
following: 
 – creation of conditions for electron oscillation in the emission region of 
the electrode system allowed to increase the energy efficiency of a glow 
discharge; 
 – obtained characteristics of the discharge with electron oscillation in the 
emission region of device allow to conclude about its application in the 
positive ion source operating at low pressure in the discharge chamber; 
 – glow discharge burning with electron oscillation is possible in two 
forms: the high-voltage and the high-current. The high-voltage form of a 
glow discharge can be used during the generation of the double-charged ions. 
 
REFERENCES 
 
1. P.A. Litvinov, V.A. Baturin, Nucl. Instrum. Meth. B 171, 573 (2000). 
2. P.A. Litvinov, V.A. Baturin, A.Yu. Karpenko, S.A. Pustovoitov, S.A. Eremin, 
Tech. Phys. 50 No4, 468 (2005). 
3. R.A. Demirhanov, Yu.V. Kursanov, V.M. Blagoveschenskiy, Instrum. Exper. 
Tech-U No1, 30 (1964). 
4. L.P. Veresov, O.L. Veresov, A.F. Chachakov, Tech. Phys. 51 No1, 130 (2006). 


English

Discharge system with electron oscillations in the emission region for the positive ion source

Electronic Sumy State University Institutional Repository

   J. Nano- Electron. Phys. 1 (2009) No2, P. 48-51 2009 SumDU (Sumy State University)   48 PACS numbers: 82.33.Xj, 29.25.Ni  DISCHARGE SYSTEM WITH ELECTRON OSCILLATIONS IN THE EMISSION REGION FOR THE POSITIVE ION SOURCE  P.A. Litvinov, V.A. Baturin  Institute of Applied Physics, National Academy of Sciences of Ukraine, 58, Petropavlivs’ka Str., 40030, Sumy, Ukraine E-mail: baturin@ipflab.sumy.ua  Design of the discharge system with electron oscillations in the emission region for the positive ion source was studied. Realization of the conditions for electron oscillation in the emission region of the electrode system allowed to increase the energy efficiency of a glow discharge. Obtained characteristics of the discharge with electron oscillation in the emission region of the discharge chamber allow to conclude about possibility of its application in the positive ion source operating at low pressure in the discharge chamber.  Keywords: DISCHARGE CHAMBER, GLOW DISCHARGE, POSITIVE IONS, ION BEAM, ION SOURCE  (Received 25 August 2009, in final form 18 September 2009)  1. INTRODUCTION  Glow discharges, because of the burning stability at current densities on the cathode up to tens A/cm2 and the simplicity of their technical realization, are attractive for application in plasma sources of charged particles. The main problem arising from such application of glow discharges consists in the necessity of the gas pressure decrease in the discharge chamber below 10 Pa for providing the electric strength of acceleration gap. The solution of this problem is achieved using the specific form of glow discharge optimized for the negative ion generation [1].  But the radial distribution of the plasma density in the emission region of this discharge system was specially made in such a way that the minimal plasma density was on the axis. Physical ideas about the processes, which take place in similar discharge system, are considered in [2], and the discharge system itself is schematically represented in Fig. 1. In the case of the positive ion extraction such distribution of the plasma density is not the optimal one.  2. EXPERIMENTAL RESULTS AND DISCUSSION  To produce the positive ion source the discharge system developed earlier for the negative ion source was changed. In the present work we discuss the results of the first experimental investigations of the modified electrode system for the positive ion generation. Structural diagram of this discharge system is represented in Fig. 2.  Plasma is generated in the double-chamber (chambers 5 and 6) inverse gas magnetron, where both the magnetic and the electrostatic fast electron confinement occur. As the result, their staying time in the magnetron chambers is large and they can make a sufficient number of ionizations for     DISCHARGE SYSTEM WITH ELECTRON OSCILLATIONS IN … 49    keeping the discharge. Both discharge chambers are hooked up parallel to the one power source. Potential difference between the electrodes of the discharge system is assigned by the automated displacement on resistances, as shown in Fig. 2.          Fig. 2 – Design of the discharge system with electron oscillation in the emission region        Fig. 1 – Design of the electrode system and the axial distribution of magnetic strength in a pole gap: 1, 2 – anode; 3, 4 – cathode; 5, 6 –chambers of high and low pressure, respectively; 7, 9 – contracting annular channels; 8 – emission chamber; 10 – biased anode; 11 – emission electrode; 12 – lower pole; 13 –magnetic circuit; 14, 15, 16, 17 –Sm-Co5 magnets L, mm 180 mm B, T u10–4 130 mm gas gas    50 P.A. LITVINOV, V.A. BATURIN     The main differences of the present electrode system from the one used by us in the negative ion source and described in [2] consist in the following: 1. Emission electrode 11 is under the cathode potential, and the mode of electron oscillation in the emission chamber 8 is realized there, that gives  a possibility to increase the energy efficiency during the positive ion extraction from plasma. 2. Geometry of the biased anode 10 is modified, and being of such design it is the main anode (MA) of the discharge system.  Known, that in glow discharges with electron oscillation there is a group of fast electrons, and though their fraction is not large, but precisely their contribution to ionization is the main one [3]. Thus, one can expect the increase of the discharge efficiency.  In Fig. 3 we present the diagram of the stretched on MA-to-the total discharge current ratio k   IMA/Id versus the total discharge current Id for the discharge with electron oscillation (Fig. 2), and the dependence of the stretched on emission electrode (EE)-to-the total discharge current ratio k   IEE/Id versus Id for the discharge without electron oscillation (Fig. 1).  1,0 1,2 1,4 1,6 1,8 2,00,600,650,700,750,800,850,90ɛɟɡɨɫɰɢɥɥɹɰɢɢɫɨɫɰɢɥɥɹɰɢɟɣkI ɪ, A Fig. 3 – Dependences of the current ratio k versus the total discharge current   The working pressure was P   310–2 Pa for the both cases. As seen from the diagram, discharge in the electrode system with electron oscillation in emission plasma has the greater energy efficiency.  In Table 1 we represent values of the discharge voltages with electron oscillation Uosc and without it Uw.osc at two values of the discharge current and working pressure in the discharge chamber 310–2 Pa and 210–2 Pa.  Analysis of the Table 1 shows that the values of voltage drop on the discharge interval in the modified electrode system have lower magnitudes in comparison with the analogue both at different values of the working pressure and at different values of the discharge current. This fact also confirms the great energy efficiency of the electrode system with electron oscillation, based on which it is proposed to produce the positive ion source.  k  Id, A  without oscillation  with oscillation     DISCHARGE SYSTEM WITH ELECTRON OSCILLATIONS IN … 51    Table 1 – Comparative characteristics of the discharge voltages with and without electron oscillation  Uosc, V Uw.osc, V Id, À Ð, Pa 380 405 1,0 390 420 1,5 310–2 395 420 1,0 410 435 1,5 210–2   We also have to note, that in some experiments we have observed the strong increase of the voltage drop on the discharge interval 8 at the pressure decrease lower than the certain critical value. A glow discharge was almost transformed into the high-voltage form. The same phenomenon takes place when the gap length between the cathode end-plane 4 and the electrode 10 increases. These two causes can be used in future for the maintenance of the high-voltage form of a glow discharge, for example, during the generation of double-charged ions.  Increase of the plasma density on the axis of the emission region of the electrode system can be achieved due to magnetic compression as it has done in [4]. The required configuration of magnetic field lines along the system can be obtained varying the number and the disposition of the beam-positioning magnets along the magnetic circuit 13. Later on it is necessary to use the water-cooling of the anode 10 as well.  3. CONCLUSIONS  Thus, based on the prior experimental results obtained we can conclude the following:  – creation of conditions for electron oscillation in the emission region of the electrode system allowed to increase the energy efficiency of a glow discharge;  – obtained characteristics of the discharge with electron oscillation in the emission region of device allow to conclude about its application in the positive ion source operating at low pressure in the discharge chamber;  – glow discharge burning with electron oscillation is possible in two forms: the high-voltage and the high-current. The high-voltage form of a glow discharge can be used during the generation of the double-charged ions.  REFERENCES  1. P.A. Litvinov, V.A. Baturin, Nucl. Instrum. Meth. B 171, 573 (2000). 2. P.A. Litvinov, V.A. Baturin, A.Yu. Karpenko, S.A. Pustovoitov, S.A. Eremin, Tech. Phys. 50 No4, 468 (2005). 3. R.A. Demirhanov, Yu.V. Kursanov, V.M. Blagoveschenskiy, Instrum. Exper. Tech-U No1, 30 (1964). 4. L.P. Veresov, O.L. Veresov, A.F. Chachakov, Tech. Phys. 51 No1, 130 (2006). 

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Discharge system with electron oscillations in the emission region for the positive ion source

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