CN104393372B - The method for suppressing dielectric surface Secondary-emission multipbcation under horizontal magnetoelectricity magnetic field model - Google Patents
The method for suppressing dielectric surface Secondary-emission multipbcation under horizontal magnetoelectricity magnetic field model Download PDFInfo
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- CN104393372B CN104393372B CN201410632331.7A CN201410632331A CN104393372B CN 104393372 B CN104393372 B CN 104393372B CN 201410632331 A CN201410632331 A CN 201410632331A CN 104393372 B CN104393372 B CN 104393372B
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Abstract
The present invention discloses a kind of method for suppressing dielectric surface Secondary-emission multipbcation under horizontal magnetoelectricity magnetic field model, and methods described includes：The first crosspoint according to secondary yield curve, determines the cyclotron frequency in magnetic field, and secondary yield curve is determined by dielectric surface material；According to the cyclotron frequency in magnetic field, magnetic field is applied in dielectric surface, dielectric surface is periodic dielectric surface, and magnetic field meets：The magnetic line of force in magnetic field is parallel；The cyclotron frequency in magnetic field is uniform within a preset range；The direction in magnetic field is perpendicular to the normal electric field direction of horizontal magnetoelectricity magnetic field model, the tangential direction of an electric field parallel to horizontal magnetoelectricity magnetic field model and parallel to dielectric surface.The method of the present invention is by using periodic dielectric surface, and apply the means in magnetic field on periodic dielectric surface, so that under different current field conditions, the method of the present invention can play certain inhibition to the multiplication of dielectric surface secondary electron, and with the raising of electric field strength, inhibition is more preferable.
Description
Technical field
The present invention relates to High-Power Microwave technical field, and in particular to one kind suppresses media table under horizontal magnetoelectricity magnetic field model
The method of face Secondary-emission multipbcation.
Background technology
High-Power Microwave (High Power Microwave, HPM) refer to peak power more than 100MW, frequency is in 1GHz
Electromagnetic radiation in the range of~300GHz.HPM has boundless application prospect in scientific research, civilian and national defence.With
The raising of the peak power and pulse width of high-power pulsed ion beams, particularly high-power, miniaturization microwave device development, position
Dielectric surface (abbreviation vacuum medium surface) in vacuum puncture have become limitation High-Power Microwave transmission and emission system
The Main Bottleneck that power is improved.
The process of vacuum medium surface breakdown is：On vacuum medium surface, due to Secondary-emission multipbcation, gas blanket is triggered
In plasma avalanche of ionization electric discharge, so as to puncture vacuum medium surface.Improve the anti-breakdown performance on vacuum medium surface
A kind of important means is that dielectric surface is processed, and domestic and international researcher is as effective by titanium nitride membrane such as Japanese KEK scholar
Secondary yield is reduced, the surface property of insulating material is improved.But, it is existing to dielectric surface at
The problem that the technology of reason is present is：The effect of suppression dielectric surface Secondary-emission multipbcation is relatively low (to be improved dielectric surface microwave to hit
The amplitude for wearing threshold value is little), reliability is not high or dielectric surface short life.
Can suppress microwave electric field parallel to dielectric surface by the way that vacuum medium surface is made as into periodic surface
The Secondary-emission multipbcation that tangential electric field component triggers, effectively improves dielectric surface microwave breakdown threshold.But, periodic surface pair
Secondary-emission multipbcation does not suppress, has enhancing to make on the contrary caused by the normal electric field component of the microwave electric field of dielectric surface
With.
The Secondary-emission multipbcation of dielectric surface can be suppressed by oscillating magnetic field, dielectric surface microwave is effectively improved and punctured threshold
Value.But, for there is the tangential electric field component of microwave electric field and the electromagnetic wave situation of normal electric field component, such as horizontal magnetic simultaneously
Electromagnetic field mode (TM patterns), oscillating magnetic field is difficult to both perpendicular to two electric field components, it is difficult to suppress Secondary-emission multipbcation.
The content of the invention
The technical problems to be solved by the invention are the existing suppression secondary electricity of dielectric surface under horizontal magnetoelectricity magnetic field model
The technology of son multiplication cannot suppress the problem of Secondary-emission multipbcation.
For this purpose, the present invention proposes a kind of side for suppressing dielectric surface Secondary-emission multipbcation under horizontal magnetoelectricity magnetic field model
Method, methods described includes：
The first crosspoint according to secondary yield curve, determines the cyclotron frequency in magnetic field, the secondary electron
Transmitting yield curve is determined by dielectric surface material；
According to the cyclotron frequency in the magnetic field, magnetic field is applied in dielectric surface, the dielectric surface is periodic dielectric table
Face, the magnetic field meets：The magnetic line of force in magnetic field is parallel；The cyclotron frequency in magnetic field is uniform within a preset range；Hang down in the direction in magnetic field
It is straight in the normal electric field direction of horizontal magnetoelectricity magnetic field model, the tangential direction of an electric field parallel to horizontal magnetoelectricity magnetic field model and parallel to
The dielectric surface.
Optionally, the periodic dimensions on the periodic dielectric surface determine according to microwave wavelength.
Optionally, 1/30 of the periodic dimensions on the periodic dielectric surface less than microwave wavelength.
Optionally, the section on the periodic dielectric surface is shaped as triangle, trapezoidal or circular arc.
Optionally, the cyclotron frequency Ω in the magnetic field meets Ω=(1~2) ω, wherein, ω is microwave angular frequency.
Compared to prior art, the side that dielectric surface Secondary-emission multipbcation is suppressed under horizontal magnetoelectricity magnetic field model of the invention
Method applies the means in magnetic field by using periodic dielectric surface on periodic dielectric surface so that in different current field conditions
Under, the method for the present invention can play certain inhibition to the multiplication of dielectric surface secondary electron, and with electric field
The raising of field intensity, the method for the present invention is more preferable to the inhibition of the multiplication of dielectric surface secondary electron.
Brief description of the drawings
Fig. 1 shows a kind of method flow diagram for suppressing dielectric surface Secondary-emission multipbcation under horizontal magnetoelectricity magnetic field model；
Fig. 2 shows the section of the cylindrical waveguide in uniform dielectric surface loading TM01 patterns；
Fig. 3 shows the section of the cylindrical waveguide in uniform dielectric surface loading TM01 patterns；
Fig. 4 (a)~(d) shows two that planar medium surface is doubled from periodic dielectric surface under different current field conditions
Secondary electron charge density is contrasted with the result of variations of normalization time t/T；
Fig. 5 (a)~(d) shows what the planar medium surface for applying different tangential magnetic fields was doubled under different current field conditions
Secondary electron charge density is contrasted with the result of variations of normalization time t/T；
Fig. 6 (a)~(d) shows the planar medium surface for applying different magnetic field with periodic dielectric surface in not same electric field
Under the conditions of double secondary electron charge density with normalization time t/T result of variations contrast.
Specific embodiment
To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present invention
In accompanying drawing, the technical scheme in the embodiment of the present invention is explicitly described, it is clear that described embodiment be the present invention
A part of embodiment, rather than whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not having
The every other embodiment obtained under the premise of creative work is made, the scope of protection of the invention is belonged to.
As shown in figure 1, the present embodiment discloses one kind suppresses dielectric surface Secondary-emission multipbcation under horizontal magnetoelectricity magnetic field model
Method, methods described may include following steps：
S1, the first crosspoint according to secondary yield curve, determine the cyclotron frequency Ω in magnetic field, and magnetic field is returned
Rotation frequency omega meets Ω=(1~2) ω, i.e. Ω is 1 to 2 times of ω, wherein, ω is microwave angular frequency, and secondary is produced
Volume curve is determined by dielectric surface material；
S2, the cyclotron frequency according to magnetic field, magnetic field is applied in dielectric surface, wherein, dielectric surface is periodic dielectric table
Face, magnetic field meets three below condition：
The magnetic line of force in magnetic field is parallel；
The cyclotron frequency in magnetic field is uniform within a preset range；
Normal electric field direction (the i.e. normal electric field component of microwave electric field of the direction in magnetic field perpendicular to horizontal magnetoelectricity magnetic field model
EnDirection), parallel to tangential direction of an electric field (the i.e. tangential electric field component E of microwave electric field of horizontal magnetoelectricity magnetic field modeltDirection)
And parallel to dielectric surface.
In a particular application, the periodic dimensions on periodic dielectric surface can make periodic dielectric according to microwave wavelength determination
1/30 of the periodic dimensions on surface less than microwave wavelength.Periodic surface can change track, transition time and the energy of electronics.
The section of the cylindrical waveguide in uniform dielectric surface loading TM01 patterns as shown in Figure 2, in the diameter model of cylinder
In enclosing, the field homogeneity of applying, the diameter of cylinder>35cm, in the present embodiment, the section on periodic dielectric surface is shaped as three
It is angular.The magnetic field for being applied to dielectric surface combines microwave electric field Erf, in ErfThe lower common acceleration electronics of × B effects, and control electronics
Transition time τ so that the transition time τ of electronics meets τ<T/2, T are the cycle of microwave, and B is the magnetic induction intensity in magnetic field, by
Cyclotron frequency Ω in magnetic field meets Ω=(1~2) ω, so B=(0.036~0.072) f, f is the frequency of microwave, does not lose
Generality, f=10GHz, then B=0.036~0.072 (Tesla).Magnetic field cyclotron frequency Ω determines the transition time τ of electronics,
The transition time τ of electronics is not substantially with microwave electric field Strength Changes.Without loss of generality, the t=0 moment, when the first face of triangle
During launching electronics, normal electric field power FnUpward (the normal electric field component E with microwave electric field in Fig. 2 in directionnIn opposite direction, Fig. 2
Middle dotted line z represents the axle perpendicular to paper), tangential electric field force FtDirection (the tangential electric field component with microwave electric field in Fig. 2 to the left
EtIt is in opposite direction).By after the transition time τ of electronics, when launching electronics collide the second face of adjacent triangle, τ<T/2,
Normal electric field power FnDirection is upward, tangential electric field force FtDirection to the left, FnAnd FtRestoring force is provided which, therefore in adjacent triangle
The secondary electron e that second face newly produces is subject to restoring force, is quickly retracted the second face of adjacent triangle, makes secondary electron e's
Collision energy realizes secondary yield less than 1, at this section less than the first crosspoint of secondary yield curve
Between continue for t ∈ (T/2- τ, T/2).T afterwards>T/2, normal electric field power FnDirection is downward, tangential electric field force FtDirection to the right, passes through
Cross the transition time τ of electronics<T/2, the launching electronics in the face of triangle second collide the first face of adjacent triangle, in time t ∈
(T/2+ τ, T), normal electric field power FnDirection keeps down, tangential electric field force FtDirection keeps to the right, FtRestoring force is provided, therefore
The secondary electron newly produced in the face of adjacent triangle first is subject to restoring force, is quickly retracted the first face of adjacent triangle, makes
The collision energy of secondary electron realizes that secondary yield is small less than the first crosspoint of secondary yield curve
In 1.By said process, realize suppressing the Secondary-emission multipbcation on vacuum medium surface, hit so as to improve dielectric surface microwave
Wear threshold value.
Under horizontal magnetic (TM) electromagnetic field mode, dielectric surface secondary electron is suppressed by applying magnetic field in dielectric surface
Multiplication, is markedly different from the microwave electric field E for only existing tangential electric fieldrfDielectric surface Secondary-emission multipbcation.Because only existing
The microwave electric field E of tangential electric fieldrfUnder effect, electronic resonance accelerates to obtain energy εe, realize εe>ε2, ε2It is the second crosspoint, and
Transition time τ~the T of electronics, T is microwave cycle；For there is normal electric field and micro- parallel with magnetic direction of tangential electric field
Ripple electric field ErfSituation, is the transition time τ by changing electronics, τ is met τ<T/2, so, when electron collision dielectric surface
When, secondary electron is subject to strong restoring force, is quickly retracted dielectric surface, the collision energy ε of secondary electroneLess than the first crosspoint
ε1, i.e. εe<ε1, realize suppressing Secondary-emission multipbcation.
Fig. 3 shows the section of the cylindrical waveguide in uniform dielectric surface loading TM01 patterns, and the magnetic field of applying is to secondary
The influence of electron multiplication can be simulated by 3-D PIC softwares.Secondary emission electron angular distribution is cosine distribution, its amplitude quilt
Normalization.Electron emission energy meets Gaussian Profile, peak energy 10eV, halfwidth 10eV.Parameter is frequency f=in simulation
11.42GHz, electronics is δ perpendicular to the incident lower secondary yield curve peak value of dielectric surfacem0=2.5, electronics peak value energy
Amount εm=400eV, surface roughness ks=1.Electron energy passes through e2Erf0 2/mω2Normalization.Abscissa is the calculating time to micro-
The normalization of period of wave (0.08ns), ordinate is the charge density of dielectric surface accumulation.
Fig. 4 (a)~(d) shows two that planar medium surface is doubled from periodic dielectric surface under different current field conditions
Secondary electron charge density is contrasted with the result of variations of normalization time t/T, and " --- " represents planar medium surface in figure, " ----"
Represent periodic dielectric surface.
The normal electric field E of Fig. 4 (a)n=0.65MV/m, tangential electric field Et=1.10MV/m；The normal electric field E of Fig. 4 (b)n=
1.94MV/m, tangential electric field Et=3.35MV/m；The normal electric field E of Fig. 4 (c)n=3.20MV/m, tangential electric field Et=5.57MV/
m；The normal electric field E of Fig. 4 (d)n=5.76MV/m, tangential electric field Et=10.0MV/m.
As can be seen that the secondary electron electric charge that can be effectively reduced by periodic dielectric surface in cylindrical waveguide cavity
Density (the E of Fig. 4 (c)nExcept the condition of=3.20MV/m), this explanation periodic dielectric sufacing can effectively suppress two
Secondary electron multiplication.
It is secondary that Fig. 5 (a)~(d) shows that the planar medium surface for applying different magnetic field is doubled under different current field conditions
Electron charge density is contrasted with the result of variations of normalization time t/T." --- " represents planar medium surface in figure, " ----" generation
Table planar medium surface applies magnetic field Bt=0.1Tesla；" ... " represents planar medium surface and applies magnetic field Bt=0.3Tesla；
" -- .-- " represent planar medium surface applying magnetic field Bt=0.5Tesla.
The normal electric field E of Fig. 5 (a)n=0.65MV/m, tangential electric field Et=1.10MV/m；The normal electric field E of Fig. 5 (b)n=
1.94MV/m, tangential electric field Et=3.35MV/m；The normal electric field E of Fig. 5 (c)n=3.20MV/m, tangential electric field Et=5.57MV/
m；The normal electric field E of Fig. 5 (d)n=5.76MV/m, tangential electric field Et=10.0MV/m.
Applying suppression of the magnetic field to Secondary-emission multipbcation has a certain effect, and the effect be mainly reflected in it is less
(the i.e. E of Fig. 5 (b) under current field conditionn=1.94MV/m conditions).When electric-field intensity strengthens, apply the suppression obtained by magnetic field
Effect is not apparent.
Fig. 6 (a)~(d) shows the planar medium surface for applying different magnetic field with periodic dielectric surface in not same electric field
Under the conditions of double secondary electron charge density with normalization time t/T result of variations contrast." --- " represents plane in figure
Dielectric surface, " ----" represent periodic dielectric surface applying magnetic field Bt=0.1Tesla, " ... " represents periodic dielectric table
Face applies magnetic field Bt=0.3Tesla, " -- .-- " represent periodic dielectric surface applying magnetic field Bt=0.5Tesla.
The normal electric field E of Fig. 6 (a)n=0.65MV/m, tangential electric field Et=1.10MV/m；The normal electric field E of Fig. 6 (b)n=
1.94MV/m, tangential electric field Et=3.35MV/m；The normal electric field E of Fig. 6 (c)n=3.20MV/m, tangential electric field Et=5.57MV/
m；The normal electric field E of Fig. 6 (d)n=5.76MV/m, tangential electric field Et=10.0MV/m.
Can be become apparent from by Fig. 6 (a)~(d), while using periodic dielectric surface and apply methods of magnetic field,
Under each current field condition certain inhibition can be played to the multiplication of secondary electron.And, it is evident that with field intensity
Raising, the technology is more preferable to the inhibition of the multiplication of secondary electron.
By comparison diagram 5 (d) and Fig. 6 (d), it can be seen that under high electric field field conditions, rely solely on applying magnetic field and come
It is undesirable to suppress the effect of Secondary-emission multipbcation, and adds periodic dielectric surface, then can well improve suppression
Effect.
By comparison diagram 5 (b) and Fig. 6 (b), it can be seen that under the conditions of this electric field strength, if simply applying magnetic field
To suppress the multiplication of secondary electron, magnetic field can play certain inhibition really, but increased periodic dielectric table
After face, under the same terms, the number density of electronics is greatly reduced (reduce about 20-30dB on year-on-year basis), and, increase magnetic field also helps
In the effect that lifting suppresses.
Although being described in conjunction with the accompanying embodiments of the present invention, those skilled in the art can not depart from this hair
Various modifications and variations are made in the case of bright spirit and scope, such modification and modification are each fallen within by appended claims
Within limited range.
Claims (3)
1. it is a kind of under horizontal magnetoelectricity magnetic field model suppress dielectric surface Secondary-emission multipbcation method, it is characterised in that the side
Method includes：
The first crosspoint according to secondary yield curve, determines the cyclotron frequency in magnetic field, the secondary
Yield curve is determined by dielectric surface material；
According to the cyclotron frequency in the magnetic field, magnetic field is applied in dielectric surface, the dielectric surface is periodic dielectric surface, institute
State magnetic field satisfaction：The magnetic line of force in magnetic field is parallel；The cyclotron frequency in magnetic field is uniform within a preset range；The direction in magnetic field is perpendicular to horizontal stroke
The normal electric field direction of magnetoelectricity magnetic field model, the tangential direction of an electric field parallel to horizontal magnetoelectricity magnetic field model and parallel to being given an account of
Matter surface；
The cyclotron frequency Ω in the magnetic field meets Ω=(1~2) ω, wherein, ω is microwave angular frequency；
The section on the periodic dielectric surface is shaped as triangle, and the magnetic field for being applied to dielectric surface combines microwave electric field
Erf, in ErfThe lower common acceleration electronics of × B effects, and control the transition time τ of electronics so that the transition time τ of electronics meets τ<
T/2, T are the cycle of microwave, and B is the magnetic induction intensity in magnetic field, the collision energy of secondary electron is produced less than secondary
First crosspoint of volume curve, realizes secondary yield less than 1, realizes suppressing the secondary electron times on vacuum medium surface
Increase.
2. method according to claim 1, it is characterised in that the periodic dimensions on the periodic dielectric surface are according to microwave
Wavelength determines.
3. method according to claim 2, it is characterised in that the periodic dimensions on the periodic dielectric surface are less than microwave
The 1/30 of wavelength.
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