JPS58117699A - Plasma device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a plasma device that enables plasma confinement using an open magnetic field.

Prior art and its problems It is well known that when confining positive i in an open magnetic field, it is necessary to lengthen the plasma confinement time in the fusion reactor, but it is not used for purposes other than the fusion reactor. Even in plasma equipment, if the confinement time is increased, the power consumption of the plasma generator can be reduced, the density of the plasma can be increased, and the heat input to the solid wall surrounding the plasma can be reduced. etc., can have great effects. Plugging at the open end is required for the ninth K, which lengthens the confinement time by Blaze confinement using an open system magnetic field. This can be seen, for example, in C. Gormezano;
Reduction of Losses in Op
en-Bidedlldagnetic Traps
; Nuclear Fusion, 19 ('79)
, 8°1085 Both of these are still under research. This electrode method includes an electromagnetic trap using an electrostatic plug consisting of an anode and a cathode at the point and line cusp of the cusp magnetic field. Figure 1 is a diagram of the principle of an electromagnetic trap, written by #TJ, Dolan, B.
L, 5tansfield and J, M, Larse
a; Plasma Potential in ele
ctrostati-cally dlugged C
u1pl and m1rrors;The Phyc
lcsof Fluids,,j ('75), 10.1
383 K and is rolled up axially symmetrically with nine pieces to form a cusp magnetic field. (2) is a hollow cylindrical anode disposed at the point cusp, (3) is a hollow cylindrical cathode disposed at the point cusp, and (4) is a pair of annular anodes disposed at the line cusp. (5) is a pair of annular cathodes arranged at the line cusp. A vacuum container (not shown) is provided in the space between the two coils (1) and the space inside the coil (1), and this vacuum container is filled with gas to become plasma. ,cathode(
An electron gun (not shown) is disposed on the opposite side of the at least 10,000 anodes (Q) of 3), and electrons emitted from this electron gun pass through the cathode (3) and the anode (2) (not shown). It moves inside the vacuum container and ionizes the nine gases it fills, forming a plasma. Dotted line (6)! , indicates the boundary of the space where plasma exists. When the potentials of the cathode (3) and the cathode (5) are zero, and the potentials of the anode (3) and the anode (4) are φm, the space potential near the Z axis is φ! The distribution is as shown in Figure 2. The potential of the space where plasma exists is φC, and O〈φ
e<φum. On both sides of the space where plasma exists,
A potential mountain is formed inside the anode (2), and the potential becomes φC+φi at the highest potential point. The electric charge of the ion is Ze,
When the electric charge of an electron is set as -e, ions whose energy is smaller than Cφ and electrons whose kinetic energy is smaller than Cφ cannot escape from the space where the plasma exists in the direction of the magnetic field.
Ions are reflected as shown by the arrow (7), and electrons are reflected as shown by the arrow (8) and are returned to the plasma. That is,
When the ion temperature of the plasma is Tl and the electron temperature is Te, φi>kT1/Ze, φ. ＞kT6/e
-(1) enables plugging at the open end of the plasma, and the confinement time can be significantly improved, which is an effect of the conventional electromagnetic trap.

This electromagnetic trap also had the following problems. Second
As shown in the figure, inside the anode (2), the space potential becomes maximum +φe, but Δφ=φmuichi (φkeφ.) ...(
The difference between the anode potential and the space potential given by 2) does not become zero, and the field is >0. The field is formed because electrons are mixed inside the anode to form a group of electrons, and the space charge created by this group of electrons forms an electrostatic field. The field is a function of the distance r from the two axes, and can be expressed as field: Δ1r). Considering the direction of the electric field created by the electron group, it can be seen that . Since the r component of the electric field is 0 on the Z axis, ~ reaches its maximum value at r=0 'rnaX %Δφmax
”Δφ(0). Therefore, the potential on the Z axis inside the anode is φi + φe = φmu Δφmax according to formula Q). φi and φ are determined by the balance of the number of particles in the plasma, etc., but they are roughly the same. Since it is a bold name of degree, φi ~ φC,
On the Z axis, . In an electromagnetic trap, Δφmax is very large and is almost equal to φm, so that on two axes, i.e., r=o, φi~φe~0. r=o, ...(3
), and it is known that equation (1) does not hold.

However, in most parts of the anode, equation (1) holds true, and equation (3
) holds only for a very small part of r, so the effect of increasing the plasma confinement time of the electrostatic plug using an electromagnetic trap is important, but as the equation (:1 holds true for r - o, the loss in the electrostatic plug The effect of increasing plasma confinement time was limited by the formation of an aperture through which the plasma leaked.

This is the tenth problem with electromagnetic traps.

Next, Figure 3 is a sectional view of the main parts of the electrostatic bladder at the point cusp of a conventional electromagnetic trap, where (2) is the anode, (2) is the anode, (
The stem is a part of the vacuum vessel that also serves as the cathode and (9) plasma third wall. As mentioned above, the electron gun shaft is placed on the opposite side of the anode (2) from the cathode (3). An energy analyzer or the like is placed in place of the Ka electron gun QQ on the opposite side of the anode from the cathode of the other electrostatic plug at the point cusp. In either case, on the opposite side of the cylindrical cathode from the anode, there is disposed a solid surface with a fixed potential and shaped to close the entrance of the cathode. Second
As is clear from the figure, the potential barrier z of the electrostatic plug
The ions exceeding φi collide with the In surface, which is at a potential of φ1 with respect to the cathode, with energy eZ (φ−φ.−φW).

φ1 can be positive, negative, or zero, but its absolute value is smaller than φ and φe, and the solid surface can be regarded as a substantial component of the cathode, and ions that collide with the solid surface are A substance is sputtered, and some of the sputtered particles are placed on the cathode (3
), it reaches the plasma through the hollow part of the anode Q) and becomes impurity ions in the plasma.

This is 11Eil) Rupp's 20th problem. In nuclear fusion plasma, suppression of impurity ions is very important in order to reduce radiation loss from the plasma, and even in plasmas used for other purposes. It is preferable that the number of impurity ions is small.

Purpose of the Invention The present invention has been made in view of the above circumstances, and its first purpose is to provide an electrostatic plug without loss aperture, and thereby to solve the problem of open system plasma with a long plasma confinement time. The second object is to provide a plasma device having an electrostatic plug that can reduce the supply of impurities to the plasma by sputtering.

Summary of the Invention The cathode of an electrostatic plug is formed by a first part in which a plurality of plates are arranged as an anode parallel to the magnetic field, and a second part forming a box shape together with the first part, A control electrode is installed in the hollow part of the anode, a projecting part is provided inside the box-shaped cathode, and an electrostatic plug without loss aperture is installed after controlling the potential of the control electrode in the hollow part of the anode. gA, a reverse magnetoresistive discharge was formed near the protrusion inside the cathode to perform an ion pumping action, and b<b> the impurities due to sputtering were suppressed from coming out of the cathode, and the purpose was already achieved.

The cusp device O-point cusp K11l can also be used in other open system plasma devices with magnetic field configuration.

Embodiment of the Invention FIG. 4 is a sectional view of the main part of an electrostatic plug showing an embodiment of the main part of the plasma apparatus of the present invention. An example is shown in which one is used in place of the electrostatic plug shown in FIG. 3 on two point cusps. The plasma confined by the cusp magnetic field and the electrostatic plug is connected via a sheath to a grounded plate (not shown), and the potential of the space where the plasma exists is φp.
is equal to the sheath voltage determined by the conduction of ions and electrons passing through the sheath and reaching the limiter, and its absolute value 1 minus 1 is smaller than the absolute value of the potential of each electrode of the electrostatic plug, which will be described later. death)
1 is an anode with a hollow part penetrating in the direction of the magnetic field, 2 is an iron anode (the anode is placed on the opposite side of the space where the odor plasma exists), and a plurality of O plates (11) are arranged parallel to the magnetic field. A first part (2) is formed facing the anode (2) with a gap provided by the spacer 0, and a part (2) is located away from the second part and is far from the anode (2). through hole α
A cathode formed from a plate portion (13) having a core and a second portion formed from a tube portion α9 fixed to the outer periphery of the plate portion Q3 and the outer periphery of the second portion. It passes through the hollow part of the through-hole αL pipe part aS of the plate part 0 of the second part of the cathode (2) and the gap of the plate aυ of the part nail of the part (M) without contacting the cathode (3) and along the magnetic field. The hollow part Km of the anode Q) is located in the rod part a
n, and a protruding part a formed in the hollow part of the cathode (151) of the tube part (151) of the second part (to) of the cathode (1) on the rod part Q71. An electrostatic plug is constructed by applying a high potential to an anode, a control electrode, and a cathode in this order from a power source (not shown), and forming an electric field having a non-zero component parallel to the direction of the magnetic field by being disposed at the point cusp.

Effect of the invention According to the present invention, the following effects can be obtained.

In the hollow part of the anode e), like the inside of the anode of the electrostatic plug at the point cusp of the electromagnetic trap, electrons are captured to form an electron group, and a stain field is formed by the space charge created by the electron group. . The difference between the electrostatic plug of the present invention and the electrostatic plug at the point cusp of an electromagnetic trap is that in the electrostatic plug of the present invention, the density of the electron group formed in the hollow part of the anode (161) is higher than that of the control electrode (161). Potential φ
8 and the anode (2) potential φaK, and as a result, the space potential in the hollow part of the anode (e) is controlled, like an electrostatic plug at the electromagnetic trap 0 point F cusp, The lowering of the potential barrier at r ” O as shown and the formation of a loss aperture due to it can be easily avoided in the electrostatic plug of the present invention. The space potential in the hollow part of the anode (2) is on the axis of symmetry. In other words, if r=o and the minimum value φ0, then the radius of the inner surface of the anode Q) is R1.
1 and the control electrode is at r=~, then φ0 is. Since the formula (7) holds true, by selecting the values of φa and φg, as described above, 1φ, 1×φg, φa (5), so φ0>φ, (6) can be obtained. The electrostatic plug in is used so that conditional expression (6) is satisfied.

Since φ is established, φk〈φ
,〈φ. It can be seen that 〈φa(8) holds true.

Since φ0 is the minimum value of the space potential in the hollow part of the anode (9), for all r, potential barriers for both ions and electrons are formed as shown in Figure 2, and the loss aperture is Turns out it doesn't exist. Plasma exists inside the not-illustrated slot, and the anode a)
It is isolated from the electron group formed in the hollow part of. Ions are reflected by the potential barrier (φ(rtZt)→, )ZK, and electrons are reflected by the potential barrier φp−φk. Here, φ(rlZt) is the space potential of the hollow part of the anode Q). The relation corresponding to (1), φ. -φp>kT1/Ze, φ, -φk>kT,/e
- can be easily realized because equation (6) holds true. Therefore, the first effect of the present invention is that it is possible to realize an open system plasma device that can significantly increase the plasma confinement time.

Ions in thermal motion are ejected from the plasma toward the electrostatic plug. Most of the ions are at the anode (2) mentioned above.
The ions are reflected by the potential barrier created by the space potential in the hollow part and returned to the plasma, but some of the ions are removed by the anode)
It passes through the hollow part of and heads toward the cathode ■. A part of the ions directed toward the cathode ■ collide with the end of the plate aD in the first part, but
Most of it passes through the gap between the plates αυ, passes through the hollow part of the tube α9 of the second part, collides with 1[11 (13), and sputters the surface material.Here, the electric potential φg is controlled. The electrode (161 has a divine capital aη and an overhanging portion a), and the overhanging portion a
8 is surrounded by the plate part a3 of the second part of the cathode and the tube part (15
1 and the first 0 parts are surrounded by a box-shaped part of the cathode at potential φ. φg〉φ, and the potential difference φ2
-φ is made large, so there is a reverse magnet around the protrusion a♂).

A discharge-type electromagnetic field configuration is formed, and electrons are captured to form an electron group. Most of the surface material of the sputtered plate portion a3 is incident on the electron group and is ionized. This process is the same as the evacuation process of an inverted magnetron type ion pump, and most of the sputtered surface material of the plate part α3 adheres to the inner surface of the box-shaped part of the cathode (3), so the sputtered The amount of substances supplied to the plasma and becoming plasma impurities can be reduced. This is the second effect of the present invention.

[Brief explanation of the drawing]

Figure 11 is a diagram of the principle of an electromagnetic trap, Figure 2 is a line diagram showing the distribution of space potential near the two axes of the electromagnetic trap, Figure 3 is a sectional view of the main parts of the electrostatic plug at the point cusp of a conventional electromagnetic trap, FIG. 4 is a sectional view of the main part of an electrostatic plug showing an embodiment of the main part of the Goodsmer device of the present invention. (1)...Coil (fi, (4)...Anode (3), (5)...Cathode (9)...Part of the vacuum vessel a...Plate (131...Plate) Part 1
101 Through hole α・Pipe part aei...Control electrode α・°゛rod・Protruding part C31)...First partial name...Second partial agent Patent attorney Chika Nori Kensuke (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] a device for generating an open magnetic field containing plasma; a means for controlling the potential of a space where the plasma exists; and an electric field disposed at the open end of the open magnetic field and having a non-zero component parallel to the direction of the magnetic field. In the plasma apparatus, at least one of the electrostatic plugs has an anode that penetrates in the direction of the magnetic field and has a hollow part, and an anode that is opposite to the space where plasma exists in the skeleton anode. A curved portion that is disposed at a distance from the skeleton anode on the side and is formed by having a plurality of slopes parallel to the magnetic field and with gaps Km between the anodes;
It is arranged in a part far from the anode and separated from the wrinkled part,
a cathode formed from a plate portion having a through hole, a second portion formed from a tube portion fixed to the outer peripheral portion of the wrinkled plate portion and the external portion of the −0th portion; a rod portion that penetrates the through hole of the plate portion of the portion, the hollow portion of the tube portion, and the gap of the plate of the first portion without contacting the cathode and extends into the hollow portion of the anode against the magnetic field; a control electrode formed from a wrinkle rod portion and a protruding portion formed in a hollow portion of a tube portion of a second portion of the cathode; and means for applying a high potential to the anode, the control electrode, and the cathode in that order. A plasma device comprising: