Were determined thermal conditions of vacuum-arc plasma sources cathodes.Stationary thermal field of the cathode with refrigeration was researched along both later a landend surfaces having different geometry of cathodes and thermal flows onto the operating surfaces.Was detected non uniformity of cathode operational surface temperature distribution along its radius. This non uniformity is greater for the cathode with refrigeration along the side surface and it can be minimized to several degrees range by changing the geometry of the cathode.Weredetermined time periods for cathodes with different refrigeration types reaching stationary thermal regime depending on cathodes’ geometry and arc current

Khaustova, А.N.

Sysoiev, Yu.A.

Tsaglov, А.I.

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 3 No 1, 01NTF03(4pp) (2014) 
 
 
2304-1862/2014/3(1)01NTF03(4) 01NTF03-1  2014 Sumy State University 
Thermal Сonditions of Technological Plasma Sources Cathodes 
 
Yu.A. Sysoiev, А.I. Tsaglov, А.N. Khaustova 
 
Zhukovskiy National Aerospase University «KAI», 17, Chkalova Str., Kharkov, Ukraine 
 
(Received 30 April 2014; published online 29 August 2014) 
 
Were determined thermal conditions of vacuum-arc plasma sources cathodes.Stationary thermal field 
of the cathode with refrigeration was researched along both later a landend surfaces having different ge-
ometry of cathodes and thermal flows onto the operating surfaces.Was detected non uniformity of cathode 
operational surface temperature distribution along its radius. This non uniformity is greater for the cath-
ode with refrigeration along the side surface and it can be minimized to several degrees range by changing 
the geometry of the cathode.Weredetermined time periods for cathodes with different refrigeration types 
reaching stationary thermal regime depending on cathodes’ geometry and arc current. 
 
Keywords: Vacuum-arc plasma source cathode, Plasma flow composition, Cathode operating surface tem-
perature, Cathode stationary thermal field, Time to reach stationary thermal regime. 
 
 PACS numbers: 29.25.Bx, 52.75.Di 
 
 
1. INTRODUCTION 
 
While analyzing the market of vacuum devices and 
technologies used top roduce wear proof, strengthening 
and other coatings, made in [1] in tensive growth (10-
15 % peryear) was noticed. It is also noticed, that a pecu-
liarity of such technologies is low cost of raw materials 
and high cost of the technology itself for the final prod-
uct. Commercial value of final product 1 kg done using 
beam technologies is around 10-30 thousand USD, which 
is 1000 times more than in  mechanical engineering and 
one rate more than for microelectronics. 
At the same time analyzing the progress of leading 
companies producing coatings, machinery and technol-
ogies of their creation in developed countries(Balzers, 
Cemicon, Metaplas, Leybold, Platit and etc.) that use 
physical vapor deposition (PVD) and also products of 
CIS scientific centers done by specialists from SPA 
“Saturn” showed that by now in Russia and abroad 
there were actually not created processes and technolo-
gies to form widely spread nanostructured multileveled 
composite coatings for industrial devices and specifical-
ly for cutting and stamping tools. 
One of the reasons for such circumstances is pres-
ence of great microparticles amount in the plasma flow 
generated by vacuum-arc plasma sources. Main param-
eter defining the number of microparticles in plasma is 
temperature of cathode operation surface. 
Research of vacuum-arc plasma sources cathodes 
thermal conditions and time to reach stationary ther-
mal regime (with refrigeration along both lateral and 
end surfaces, having different cathodes geometry and 
thermal flow intensities onto the operation surfaces) is 
the goal of the work. 
 
2. ISSUE UP TO DATE STATE 
 
Experimental data obtained for an arc with titanium 
cathode [3] show that there is major influence of integral 
temperature on erosion velocity and character. 
Insuchawayhaving unsatisfactoryheat dissipation from 
the non-operation end of rod cathode (there is powder 
graphite between the cathode and adapter) erosion 
velocity increases more than 5 times comparing to the 
cathode with direct refrigeration. Unfortunately data 
about cathode temperature and referring erosion 
velocities is absent in sources [3,4 and etc.]  
In [5] were studied possibilities and peculiarities of 
cathode with refrigeration along both lateral and end 
surfaces operation surface temperature regulation and 
stabilization. Were developed cathode nodes construc-
tions in which temperature of operation surface can be 
controlled by changing the temperature of the refriger-
ated end of the cathode, changing current of vacuum-
arc discharge and changing the distance between the 
operation surface and its refrigeration zone by moving 
the cathode. Still the temperature of operation surface 
and time period to reach stationary thermal regime of 
the cathode with different refrigeration types are not 
researched depending on the geometry and vacuum-arc 
discharge current in [5]. 
Vacuum-arc plasma source developed in [6] is char-
acterized by low micro particles content in the created 
plasma flow. Such peculiarity was reached by using 
disk cathode with initial ratio of diameter D and length 
L D / L  4. Temperature of cathode operation surface 
doesn’t exceed 500 K. During operation of a plasma 
source with such cathode geometry D / L ratio perma-
nently increases that leads to lowering the temperature 
of cathode operation surface and changes the composi-
tion of plasma flow generated.  
To obtain coatings with reproducible composition in 
[7] decreasing gorge in the rod cathode close to its opera-
tion surface takes place between sputtering cycles. Main 
imperfection of the method is a need to perform a compli-
cated process of decomposing – composing of plasma 
source cathode node after each processing cycle that 
decreases the productivity of the process. A more rational 
way to keep the temperature of cathode operation surface 
constant in a separate sputtering cycle is a method of 
changing refrigerating liquid flow suggested in [5]. 
There is a noticeable increase of cathode plasma 
forming substance provided in constructions of vacuum-
arc plasma sources with refrigeration of the cathode 
along the lateral surface [8]. Such composition allows to 
move the cathode with respect to its depletion. This 
 YU.A. SYSOEV, A.I. TSAGLOV, A.N. KHAUSTOVA PROC. NAP 3, 01NTF03 (2014) 
 
 
01NTF03-2 
take saway the limitation of cathode material. Also 
stabilization of cathode operation surface temperature 
takes place due to absence of distance change between 
it and the refrigeration zone. 
Still when practically realizing plasma sources of 
such type there stays the question about cathode 
geometry (its radius) cause while increasing the radius 
of the cathode there might increase temperature 
nonuniform distribution along the operation surface.  
 
3. EXPERIMENTAL RESULTS AND DISCUS-
SIONS 
 
3.1 Thermal Regime of Cathode Refrigerated 
Along and Surface 
 
Modelling temperature of cathode with refrigerated 
end surface was based on the developed mathematic 
model that takes counts heat losses due to radiation 
using finite element method. Results of thermal fields 
on cathode operation surface having different cathode 
length L, radius R, arc currents IД are given in Fig. 1-3. 
 
 
 
Fig. 1 – Cathode operation surface maximum temperature 
with refrigeration along thee and with respect to arccur-
rent:R = 0.03 m 
 
Increasing arccurrent Iд effects to in crease of power 
Рк that executes on the cathode that leads to raise of 
operation surface maximum temperature (Fig. 1). In 
this case temperature is linear, growth velocity is in 
proportion to cathode length L and in inverse 
proportion to radius R. Having valuable cathode length 
increase катода (R  0.03 m and L  0.035 m)radiation 
energy losses from the operation surface start to 
valuably effect that leads to temperature growth 
slowdown (Fig. 2). When L  0.30 m energy losses are 
equal to the energy delivered to the cathode and 
operation surface temperature stabilizes and the value 
of 1695 K. When the radius of the cathode is greater 
temperature stabilization takes place at greater 
cathode lengths.  
Increasing cathode radius leads to lowering opera-
tion surface temperature (the greater is the length of 
the cathode the faster) that happens due to decreasing 
specific power delivered to the surface of the cathode. 
Radiation energy losses from cathode lateral surface 
lead to temperature non uniform distribution along the 
 
 
Fig. 2 – Cathode operation surface maximum temperature 
with refrigeration along thee and with respect to its 
length:R = 0.03 m 
 
radius of cathode operation surface: maximum value in 
the center and minimum on the distance equal to the 
radius of the cathode. This temperature gradient ∆Т is 
insignificant (several hundredths of degree at L  5 mm 
and not exceeding 0.65 at L  10 mm – Fig. 3). Still this 
gradient increases when L increases and can reach up 
to several tens degrees, though gradient value 
decreases with cathode radius increase. 
 
 
 
Fig. 3 – Temperature gradient on cathode operation surface 
with refrigeration along thee and with respect to its length at 
different arccurrents: R = 0.03 m 
 
Time to reach stabilization of cathode operation 
surface is an important parameter because it allows to 
define the time after which plasma source will be 
generating plasma flow of constant composition. In the 
newest ion-plasma devices it will allow to define the 
time opening the cap that separates plasma flow from 
the processed surface after plasma source is on [9].  
Time to reach static thermal regime of the cathode 
considerably depends on the mass of the cathode and 
arc current, it increases with increase of cathode mass 
and decreases with arc current increase (Fig. 4). To 
provide acceptable timing for cathode with refrigeration 
along end surface (tв  100 s) it is required to use 
cathodes with length L not exceeding 0.02 m and radius 
R not exceeding 0.05 m. With such geometrical 
parameters maximum temperature of cathode 
operation surface doesn’t exceed 600 K that leads to 
respectively low content of drop fraction in plasma flow. 
 THERMAL CONDITIONS OF THECHNOLOGICAL PLASMA SOURCES CATHODES PROC. NAP 3, 01NTF03 (2014) 
 
 
01NTF03-3 
 
 
Fig. 4 –Time to reach stationary thermal regime for cathode 
with refrigeration along then on operation surface with respect 
the length of the cathode at different arccurrents: R = 0.03 m 
 
3.2 Thermal Regime of Cathode with Refrigera-
tion Along Lateral Surface 
 
Comparing maximum temperature cathode 
refrigerated along the nonoperation end operation 
surface (Fig. 1) with that of the cathode refrigerated 
along the lateral surface (Fig. 5) shows that the least 
value of this parameter is detected for the cathode 
refrigerated along the end surface (309 Кat R  0.06 m 
and L  0.005 m for the cathode refrigerated along the 
end versus 423 К at R  0.05 m and l3  0.005 m for the 
cathode refrigerated along the lateral surface). 
It is remarkable high temperature of cathode 
refrigerated along the lateral surface operation surface  
at low cathode radiuses that can be explained with 
inverse square dependence of thermal flow density onto 
the cathode depending on its radius (at R  0.01 m 
thermal flow density onto the surface of the cathode is 
one digit greater than that when R  0.03 m). 
 
 
 
Fig. 5 – Maximum temperature of cathode refrigerated along 
lateral surface operation surface with respect to arccurrent: 
L = 0.01 m 
 
In the case of refrigeration along lateral surface 
unlike refrigeration along the end there is detected a 
more expressed cathode operation surface temperature 
increase with arc current increase and there is no its 
stabilization. Also there can be noticed a more 
expressed decrease of cathode operation surface 
maximum temperature with increase of cathode radius 
(Fig. 6). 
For the case when cathode is refrigerated along the  
 
 
Fig. 6 – Maximum temperature of cathode refrigerated along 
lateral surface operation surface with respect to arccurrent: 
L = 0.04 m 
 
later al surface is representative higher operation 
surface temperature gradientt hat reaches 100 degrees. 
This temperature gradient can be minimized up to 
several degrees by changing the length of the cathode 
operation part l and its radius R (Fig. 7). Them inimal 
temperature gradient achieved will be constant while 
keeping l constant, same as maximum temperature of 
cathode refrigerated along lateral surface operation 
surface. 
 
 
 
Fig. 7 – Temperature gradient on cathode refrigerated along 
lateral surface operation surface with respect to cathode lengt 
hat different arccurrents: R = 0.04 m 
 
Havin glow values of cathode operation part  
(l   (0,005-0.01) m) time to reach stationary regime is 
small almost doesn’t depend on arc current and is only 
defined by the radius of the cathode (Fig. 8). When 
increasing the length of cathode operation part (l  (0.02 
-0.04) m) time to reach stationary temperature regime 
decrease is observed when increasing arc current (most 
significant for cathodes withR ≥ 0.03 m). 
Comparing time to reach stationary regime for 
cathode soft he same radius (R  0.03 m) but having 
different refrigeration types shows that warm-up time 
of the cathode refrigerated along lateral surface is 
greater. In the case of cathode length slow values 
(l  (0.005-0.01) m) the difference is (6-12) times, when 
increasing cathode length (l  (0.02-0.04) m) warm-up 
time difference decreases to about 2 times or less. 
 YU.A. SYSOEV, A.I. TSAGLOV, A.N. KHAUSTOVA PROC. NAP 3, 01NTF03 (2014) 
 
 
01NTF03-4 
Alsowhenobservinghighcathoderefrigeratedalonglateral
surfacelengthvaluesdependence of time to reach 
stationary temperature from arc current is nonlinear 
(Fig. 9) meanwhile it is linear for cathode refrigerated 
along nonoperation end surface. 
 
 
 
Fig. 8 – Time to reach stationary regime for cathode refriger-
ated alongn on operation surface with respect to cathode 
length at different arccurrents: R = 0.03 
 
 
 
Fig. 9 – Time to reach stationary regime for cathode refriger-
ated alongn on operation surface with respect arccurrents: 
R = 0.03 m 
 
4. CONCLUSION 
 
Results, obtained in this work can be generalized in the 
following way: 
 for cathode refrigerated along non operation and 
were obtained laws of operation surface temperature 
changing depending on the changes of geometrical 
parameters of the cathode and arc current: maximum 
temperature value is directly proportional to the length 
of the cathode and arc current and reverse proportional 
to the radius of the cathode. When valuably increasing 
cathode length (R  0.03 mand L  0.035 m) radiation 
energy losses from cathode operation surface start to 
appreciably influence. This leads to deceleration of 
temperature growth and its further stabilization. 
Obtained laws allow to define optimal temperature 
regime for plasma source cathode while designing; 
 non uniform distribution of temperature along 
radius of cathode refrigerated along the end operation 
surface was obtained with maximum in the center of 
the cathode and minimum on the distance equal to the 
value of cathode radius, it is aligned with cathode 
lateral surface radiation energy losses. With low values 
of cathode length L temperature gradient ∆Т is 
insignificant (when L  5 mmab out hundreds digit of 
degree, when L  10 mm doesn’t exceed 0.65 К). Though 
this gradient increases with L increase and can reach 
several tens degrees, also its value decreases with 
increase of cathode radius; 
 time to reach stationary thermal regime law was 
defined for cathode refrigerated on the end was defined. 
Top rovide accept able time storeach work regime for 
cathode refrigerated along and surface (tв  100 s) in 
the constructions of plasma sources it is required to use 
cathodes with length L not more than 0.02 mand radius 
R, not exceeding values about 0.05m; 
 it was defined that maximum temperature of 
cathode refrigerated along nonoperation end operation 
surface have other conditions the same is less than that 
of the cathode refrigerated along lateral surface; 
 it was proved that higher temperature gradient on 
cathode operation surface can be minimized up to 
values of several degrees by changing the length of 
cathode operation part l and its radius R. 
 it was determined tat time to reach stationary 
thermal regime for cathodes of the same radius 
(R  0.03 m) is less in the case of the cathode 
refrigerated along end surface. With low length of 
cathode (l3  (0.005-0.01) m) thisdifferenceconcludes (6-
12) times, increasing cathode length(l3  (0.02-0.04) m) 
difference in cathode warm-up times decreases up to 2 
and less times. 
 
 
REFERENCES 
 
1. Tekhnologiya i oborudovanie formirovanie vysoko-
kachestvennykh uprochnyayuschikh poverkhnostnykh 
structur izdelii magnetronno-duhovymi plazmennymi poto-
kami [in Russian]. 
2. V.N. Krylov, V.A. Krylov, V.A. Poletaev, T.D. Kozhyna, – 
http://85.142.23.144/packages/mifi/C6886AA4-A711-4C2F-
93D1-C0A9D2490CEE/1. 0.0.0/file.pdf. 
3. V.M. Khoroshikh. Phys. Surface Eng. 2 No 14, 184 (2004).  
4. J.E. Daalder, J. Phys. D: Appl. Phys. 8 No 14, 1647 (1975). 
5. Yu. Sysoev, I. Tatarkina, 3rd Int. Conf. «Nanomaterials: 
Applications & Properties – 2013 (NAP-2013)», 2 No 3, 
03AET02 (2013). 
6. A.V. Kabanov, Uprochnyayuschie tekhnologii I pokrytiya 
No 3, 3 (2013) [in Russian]. 
7. Patent 2361014RU, Int. Cl.C23C14/40 (2006). 
8. Patent3625858 US, Int. Cl.С23C15/00 (1971). 
9. I.I. Aksenov, V.A. Belous, VANT No 2, 108 (2008). 
 


Thermal conditions of technological plasma sources cathodes

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 3 No 1, 01NTF03(4pp) (2014)   2304-1862/2014/3(1)01NTF03(4) 01NTF03-1  2014 Sumy State University Thermal Сonditions of Technological Plasma Sources Cathodes  Yu.A. Sysoiev, А.I. Tsaglov, А.N. Khaustova  Zhukovskiy National Aerospase University «KAI», 17, Chkalova Str., Kharkov, Ukraine  (Received 30 April 2014; published online 29 August 2014)  Were determined thermal conditions of vacuum-arc plasma sources cathodes.Stationary thermal field of the cathode with refrigeration was researched along both later a landend surfaces having different ge-ometry of cathodes and thermal flows onto the operating surfaces.Was detected non uniformity of cathode operational surface temperature distribution along its radius. This non uniformity is greater for the cath-ode with refrigeration along the side surface and it can be minimized to several degrees range by changing the geometry of the cathode.Weredetermined time periods for cathodes with different refrigeration types reaching stationary thermal regime depending on cathodes’ geometry and arc current.  Keywords: Vacuum-arc plasma source cathode, Plasma flow composition, Cathode operating surface tem-perature, Cathode stationary thermal field, Time to reach stationary thermal regime.   PACS numbers: 29.25.Bx, 52.75.Di   1. INTRODUCTION  While analyzing the market of vacuum devices and technologies used top roduce wear proof, strengthening and other coatings, made in [1] in tensive growth (10-15 % peryear) was noticed. It is also noticed, that a pecu-liarity of such technologies is low cost of raw materials and high cost of the technology itself for the final prod-uct. Commercial value of final product 1 kg done using beam technologies is around 10-30 thousand USD, which is 1000 times more than in  mechanical engineering and one rate more than for microelectronics. At the same time analyzing the progress of leading companies producing coatings, machinery and technol-ogies of their creation in developed countries(Balzers, Cemicon, Metaplas, Leybold, Platit and etc.) that use physical vapor deposition (PVD) and also products of CIS scientific centers done by specialists from SPA “Saturn” showed that by now in Russia and abroad there were actually not created processes and technolo-gies to form widely spread nanostructured multileveled composite coatings for industrial devices and specifical-ly for cutting and stamping tools. One of the reasons for such circumstances is pres-ence of great microparticles amount in the plasma flow generated by vacuum-arc plasma sources. Main param-eter defining the number of microparticles in plasma is temperature of cathode operation surface. Research of vacuum-arc plasma sources cathodes thermal conditions and time to reach stationary ther-mal regime (with refrigeration along both lateral and end surfaces, having different cathodes geometry and thermal flow intensities onto the operation surfaces) is the goal of the work.  2. ISSUE UP TO DATE STATE  Experimental data obtained for an arc with titanium cathode [3] show that there is major influence of integral temperature on erosion velocity and character. Insuchawayhaving unsatisfactoryheat dissipation from the non-operation end of rod cathode (there is powder graphite between the cathode and adapter) erosion velocity increases more than 5 times comparing to the cathode with direct refrigeration. Unfortunately data about cathode temperature and referring erosion velocities is absent in sources [3,4 and etc.]  In [5] were studied possibilities and peculiarities of cathode with refrigeration along both lateral and end surfaces operation surface temperature regulation and stabilization. Were developed cathode nodes construc-tions in which temperature of operation surface can be controlled by changing the temperature of the refriger-ated end of the cathode, changing current of vacuum-arc discharge and changing the distance between the operation surface and its refrigeration zone by moving the cathode. Still the temperature of operation surface and time period to reach stationary thermal regime of the cathode with different refrigeration types are not researched depending on the geometry and vacuum-arc discharge current in [5]. Vacuum-arc plasma source developed in [6] is char-acterized by low micro particles content in the created plasma flow. Such peculiarity was reached by using disk cathode with initial ratio of diameter D and length L D / L  4. Temperature of cathode operation surface doesn’t exceed 500 K. During operation of a plasma source with such cathode geometry D / L ratio perma-nently increases that leads to lowering the temperature of cathode operation surface and changes the composi-tion of plasma flow generated.  To obtain coatings with reproducible composition in [7] decreasing gorge in the rod cathode close to its opera-tion surface takes place between sputtering cycles. Main imperfection of the method is a need to perform a compli-cated process of decomposing – composing of plasma source cathode node after each processing cycle that decreases the productivity of the process. A more rational way to keep the temperature of cathode operation surface constant in a separate sputtering cycle is a method of changing refrigerating liquid flow suggested in [5]. There is a noticeable increase of cathode plasma forming substance provided in constructions of vacuum-arc plasma sources with refrigeration of the cathode along the lateral surface [8]. Such composition allows to move the cathode with respect to its depletion. This  YU.A. SYSOEV, A.I. TSAGLOV, A.N. KHAUSTOVA PROC. NAP 3, 01NTF03 (2014)   01NTF03-2 take saway the limitation of cathode material. Also stabilization of cathode operation surface temperature takes place due to absence of distance change between it and the refrigeration zone. Still when practically realizing plasma sources of such type there stays the question about cathode geometry (its radius) cause while increasing the radius of the cathode there might increase temperature nonuniform distribution along the operation surface.   3. EXPERIMENTAL RESULTS AND DISCUS-SIONS  3.1 Thermal Regime of Cathode Refrigerated Along and Surface  Modelling temperature of cathode with refrigerated end surface was based on the developed mathematic model that takes counts heat losses due to radiation using finite element method. Results of thermal fields on cathode operation surface having different cathode length L, radius R, arc currents IД are given in Fig. 1-3.    Fig. 1 – Cathode operation surface maximum temperature with refrigeration along thee and with respect to arccur-rent:R = 0.03 m  Increasing arccurrent Iд effects to in crease of power Рк that executes on the cathode that leads to raise of operation surface maximum temperature (Fig. 1). In this case temperature is linear, growth velocity is in proportion to cathode length L and in inverse proportion to radius R. Having valuable cathode length increase катода (R  0.03 m and L  0.035 m)radiation energy losses from the operation surface start to valuably effect that leads to temperature growth slowdown (Fig. 2). When L  0.30 m energy losses are equal to the energy delivered to the cathode and operation surface temperature stabilizes and the value of 1695 K. When the radius of the cathode is greater temperature stabilization takes place at greater cathode lengths.  Increasing cathode radius leads to lowering opera-tion surface temperature (the greater is the length of the cathode the faster) that happens due to decreasing specific power delivered to the surface of the cathode. Radiation energy losses from cathode lateral surface lead to temperature non uniform distribution along the   Fig. 2 – Cathode operation surface maximum temperature with refrigeration along thee and with respect to its length:R = 0.03 m  radius of cathode operation surface: maximum value in the center and minimum on the distance equal to the radius of the cathode. This temperature gradient ∆Т is insignificant (several hundredths of degree at L  5 mm and not exceeding 0.65 at L  10 mm – Fig. 3). Still this gradient increases when L increases and can reach up to several tens degrees, though gradient value decreases with cathode radius increase.    Fig. 3 – Temperature gradient on cathode operation surface with refrigeration along thee and with respect to its length at different arccurrents: R = 0.03 m  Time to reach stabilization of cathode operation surface is an important parameter because it allows to define the time after which plasma source will be generating plasma flow of constant composition. In the newest ion-plasma devices it will allow to define the time opening the cap that separates plasma flow from the processed surface after plasma source is on [9].  Time to reach static thermal regime of the cathode considerably depends on the mass of the cathode and arc current, it increases with increase of cathode mass and decreases with arc current increase (Fig. 4). To provide acceptable timing for cathode with refrigeration along end surface (tв  100 s) it is required to use cathodes with length L not exceeding 0.02 m and radius R not exceeding 0.05 m. With such geometrical parameters maximum temperature of cathode operation surface doesn’t exceed 600 K that leads to respectively low content of drop fraction in plasma flow.  THERMAL CONDITIONS OF THECHNOLOGICAL PLASMA SOURCES CATHODES PROC. NAP 3, 01NTF03 (2014)   01NTF03-3   Fig. 4 –Time to reach stationary thermal regime for cathode with refrigeration along then on operation surface with respect the length of the cathode at different arccurrents: R = 0.03 m  3.2 Thermal Regime of Cathode with Refrigera-tion Along Lateral Surface  Comparing maximum temperature cathode refrigerated along the nonoperation end operation surface (Fig. 1) with that of the cathode refrigerated along the lateral surface (Fig. 5) shows that the least value of this parameter is detected for the cathode refrigerated along the end surface (309 Кat R  0.06 m and L  0.005 m for the cathode refrigerated along the end versus 423 К at R  0.05 m and l3  0.005 m for the cathode refrigerated along the lateral surface). It is remarkable high temperature of cathode refrigerated along the lateral surface operation surface  at low cathode radiuses that can be explained with inverse square dependence of thermal flow density onto the cathode depending on its radius (at R  0.01 m thermal flow density onto the surface of the cathode is one digit greater than that when R  0.03 m).    Fig. 5 – Maximum temperature of cathode refrigerated along lateral surface operation surface with respect to arccurrent: L = 0.01 m  In the case of refrigeration along lateral surface unlike refrigeration along the end there is detected a more expressed cathode operation surface temperature increase with arc current increase and there is no its stabilization. Also there can be noticed a more expressed decrease of cathode operation surface maximum temperature with increase of cathode radius (Fig. 6). For the case when cathode is refrigerated along the    Fig. 6 – Maximum temperature of cathode refrigerated along lateral surface operation surface with respect to arccurrent: L = 0.04 m  later al surface is representative higher operation surface temperature gradientt hat reaches 100 degrees. This temperature gradient can be minimized up to several degrees by changing the length of the cathode operation part l and its radius R (Fig. 7). Them inimal temperature gradient achieved will be constant while keeping l constant, same as maximum temperature of cathode refrigerated along lateral surface operation surface.    Fig. 7 – Temperature gradient on cathode refrigerated along lateral surface operation surface with respect to cathode lengt hat different arccurrents: R = 0.04 m  Havin glow values of cathode operation part  (l   (0,005-0.01) m) time to reach stationary regime is small almost doesn’t depend on arc current and is only defined by the radius of the cathode (Fig. 8). When increasing the length of cathode operation part (l  (0.02 -0.04) m) time to reach stationary temperature regime decrease is observed when increasing arc current (most significant for cathodes withR ≥ 0.03 m). Comparing time to reach stationary regime for cathode soft he same radius (R  0.03 m) but having different refrigeration types shows that warm-up time of the cathode refrigerated along lateral surface is greater. In the case of cathode length slow values (l  (0.005-0.01) m) the difference is (6-12) times, when increasing cathode length (l  (0.02-0.04) m) warm-up time difference decreases to about 2 times or less.  YU.A. SYSOEV, A.I. TSAGLOV, A.N. KHAUSTOVA PROC. NAP 3, 01NTF03 (2014)   01NTF03-4 Alsowhenobservinghighcathoderefrigeratedalonglateralsurfacelengthvaluesdependence of time to reach stationary temperature from arc current is nonlinear (Fig. 9) meanwhile it is linear for cathode refrigerated along nonoperation end surface.    Fig. 8 – Time to reach stationary regime for cathode refriger-ated alongn on operation surface with respect to cathode length at different arccurrents: R = 0.03    Fig. 9 – Time to reach stationary regime for cathode refriger-ated alongn on operation surface with respect arccurrents: R = 0.03 m  4. CONCLUSION  Results, obtained in this work can be generalized in the following way:  for cathode refrigerated along non operation and were obtained laws of operation surface temperature changing depending on the changes of geometrical parameters of the cathode and arc current: maximum temperature value is directly proportional to the length of the cathode and arc current and reverse proportional to the radius of the cathode. When valuably increasing cathode length (R  0.03 mand L  0.035 m) radiation energy losses from cathode operation surface start to appreciably influence. This leads to deceleration of temperature growth and its further stabilization. Obtained laws allow to define optimal temperature regime for plasma source cathode while designing;  non uniform distribution of temperature along radius of cathode refrigerated along the end operation surface was obtained with maximum in the center of the cathode and minimum on the distance equal to the value of cathode radius, it is aligned with cathode lateral surface radiation energy losses. With low values of cathode length L temperature gradient ∆Т is insignificant (when L  5 mmab out hundreds digit of degree, when L  10 mm doesn’t exceed 0.65 К). Though this gradient increases with L increase and can reach several tens degrees, also its value decreases with increase of cathode radius;  time to reach stationary thermal regime law was defined for cathode refrigerated on the end was defined. Top rovide accept able time storeach work regime for cathode refrigerated along and surface (tв  100 s) in the constructions of plasma sources it is required to use cathodes with length L not more than 0.02 mand radius R, not exceeding values about 0.05m;  it was defined that maximum temperature of cathode refrigerated along nonoperation end operation surface have other conditions the same is less than that of the cathode refrigerated along lateral surface;  it was proved that higher temperature gradient on cathode operation surface can be minimized up to values of several degrees by changing the length of cathode operation part l and its radius R.  it was determined tat time to reach stationary thermal regime for cathodes of the same radius (R  0.03 m) is less in the case of the cathode refrigerated along end surface. With low length of cathode (l3  (0.005-0.01) m) thisdifferenceconcludes (6-12) times, increasing cathode length(l3  (0.02-0.04) m) difference in cathode warm-up times decreases up to 2 and less times.   REFERENCES  1. Tekhnologiya i oborudovanie formirovanie vysoko-kachestvennykh uprochnyayuschikh poverkhnostnykh structur izdelii magnetronno-duhovymi plazmennymi poto-kami [in Russian]. 2. V.N. Krylov, V.A. Krylov, V.A. Poletaev, T.D. Kozhyna, – http://85.142.23.144/packages/mifi/C6886AA4-A711-4C2F-93D1-C0A9D2490CEE/1. 0.0.0/file.pdf. 3. V.M. Khoroshikh. Phys. Surface Eng. 2 No 14, 184 (2004).  4. J.E. Daalder, J. Phys. D: Appl. Phys. 8 No 14, 1647 (1975). 5. Yu. Sysoev, I. Tatarkina, 3rd Int. Conf. «Nanomaterials: Applications & Properties – 2013 (NAP-2013)», 2 No 3, 03AET02 (2013). 6. A.V. Kabanov, Uprochnyayuschie tekhnologii I pokrytiya No 3, 3 (2013) [in Russian]. 7. Patent 2361014RU, Int. Cl.C23C14/40 (2006). 8. Patent3625858 US, Int. Cl.С23C15/00 (1971). 9. I.I. Aksenov, V.A. 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Thermal conditions of technological plasma sources cathodes

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