JPH03105283A - Supplying equipment of pellet acceleration gas - Google Patents

Abstract

PURPOSE:To improve a performance of acceleration of a pellet by accelerating the pellet after adiabatic compression of an acceleration gas is ended completely. CONSTITUTION:An acceleration gas filling chamber 11 is subjected to adiabatic compression by rapid sliding of a plunger 2 to the right. The plunger 2 proceeds to the right with acceleration until a pressure in a filling chamber 10 becomes equal to a pressure in the filling chamber 11 and thereafter it applies the compression further to the filling chamber 11 with deceleration. At the time point when the plunger 2 strikes on a stopper 3 and stops, as the result, the pressure in the filling chamber 11 can be made higher than that in the filling chamber 10 and, in addition, the temperature of a gas can be made high. When the adiabatic compression of the pellet acceleration gas is ended, a gas vent 14 of a valve 13 is opened to stop pressing of a plunger 9. The plunger 9 is pushed upward by a pressure of the compressed acceleration gas and, consequently, an outlet 7 opens, the acceleration gas flowing into a pellet producing element 22. According to this constitution, acceleration of a pellet can be performed by adjusting a compression ratio of the acceleration gas.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pellet injection device for a nuclear fusion device, and in particular,
The present invention relates to a pellet accelerating gas supply device suitable for repeated high-speed injection of pellets.

[Conventional technology]

The pellet injection device of the fusion device cools and solidifies the hydrogen isotope fuel of the fusion device to create pellets, and then
This is a device that controls the density of plasma by accelerating it to a speed of m/s and repeatedly injecting it into a nuclear fusion device.

Regarding conventional pellet injection devices, see Milora et al., IAEA, Technical Committee Meeting on Pellet Injection and Toroidal Confinement (West Germany, 1988).
Technical Committee Mee
ting on Pellet Injection
and Toroidal Confinem
ent (FRG, 1988)). Second
The figure is a schematic diagram of the pellet injection device shown in the above-mentioned document, in which (a) shows the time of pellet generation and (b) shows the time of pellet injection. The device includes a pellet generation section 22, an acceleration gas supply valve 2
6 and barrel 23. The pellet production section 22 is cooled to below the solidification temperature of hydrogen by a heat exchanger 25 to produce solid hydrogen pellets 24.

Next, pellet accelerating gas at a pressure of about 10 MPa is introduced from the accelerating gas inlet 6 of the valve 26 to fill the filling chamber 11. Before accelerating the pellets, the plunger 9 of the valve 26 is pressed against the accelerating gas outlet 7 to confine the accelerating gas in the filling chamber 11, as shown in (a).

When accelerating the pellet, the coil 17 that drives the plunger 9 is energized to move the plunger away from the accelerating gas outlet 7 as shown in (b). The pellets 24 are accelerated by the propulsive force of the accelerating gas in the filling chamber 11, and are ejected within the gun barrel 23 while increasing their speed.

The equation of motion of the pellet 24 due to the accelerating gas can be expressed as follows (1). Here, Mpe Up and Ap are the mass, velocity, and cross-sectional area of each pellet. Also, P, Co
, -δ are the pressure, sound velocity, and specific heat ratio of the respective accelerating gases. The pressure waveform of the accelerating gas is as shown in Figure 3. The waveform has a finite rise time τ due to the shape of the valve 26, the opening/closing time, etc. τ2 is about lms for a fast device and about 20ms for a slow device, and the pressure P(t) between 0<1<τ is P(t)=ct...(2)
It can be approximated by a straight line, as in Here, C is the pressure increase rate. When the pellet speed is determined by substituting equation (2) into equation (1), the following is obtained: (3).

From equation (3), to increase the acceleration performance of the pellet 24,
(i) Lengthening the gun barrel 23 to lengthen the acceleration time; (
It is effective to ii) increase the pressure increase rate C of the accelerating gas, and (m) increase the speed of sound Go by heating the accelerating gas.

Regarding the gun barrel, if it is made too long, the frictional force between the pellet 24 and the gun barrel 23 will increase, and a significant increase in speed cannot be expected. is selected. As shown in FIG. 2, the valve 26 is directly connected to the pellet generating section 22 (usually installed very close to it in several countries) to supply accelerating gas in order to shorten the rise time τ of the pressure wave and increase the pressure rise rate C. I'm hoarding it.

Therefore, if the valve 26 is heated too much in order to increase the sonic velocity Go of the gas, the amount of heat entering the pellet generating section 22 will increase, and the pellets 24 will be heated beyond the cooling capacity of the heat exchanger 25 and melted.

Conventionally, in the apparatus shown in FIG. 2, the maximum temperature of the accelerating gas is about 400° C., and the velocity of the pellet is about 2 k+s/s.

FIG. 4 shows another pellet injection device reported in the above-mentioned literature, which aims at high-speed injection of 2 km/s or more.

(a) is before pellet injection, (b) is after pellet injection. (a
), the accelerating gas is stored in the filling chamber 11, but the pellet 24 does not run through the barrel 23 (the position where the pellet 24 is stopped is provided with grooves or the like to increase friction). The filling chamber 11 is bordered by a high-pressure gas reservoir 30 and a rupture disk 31, and further has a piston 2 on the filling chamber side for compressing accelerating gas. When the pressure in the high-pressure reservoir 30 is rapidly increased and the rupture disk ruptures as shown in FIG. 3(b), the piston 2 moves to the right and adiabatically compresses the accelerating gas in the filling chamber 11. When the pressure of the compressed accelerating gas exceeds a certain value, the pellet 24 is pushed into the gun barrel 23.
The gas is injected by overcoming the frictional force with the gas, but the pressure P and temperature T of the gas at that time are as follows. Here, Vo, Pa, and To are the volume of the filling chamber before compression, gas pressure, and gas temperature, V, P, and T are the above-mentioned quantities after compression, and δ is the specific heat ratio of the gas.

As a result of the above equations (4) and (5), the low-temperature gas confined in the filling chamber 11 of the filling chamber t1 can be heated without heating the peripheral devices, and can be made to have a high pressure. Therefore, compared to the device shown in FIG. 2, the device shown in FIG. 4 has less heat intrusion into the pellet feeding section and has improved acceleration performance.

[Problem to be solved by the invention]

The above conventional technique shown in FIG. 4 has the following problems.

While the accelerating gas is being adiabatically compressed, the pellet 24 must remain stationary and immediately start running as soon as the compression ends. However, in reality, once a certain gas pressure is exceeded, the pellet 24 begins to accelerate slowly. It is not possible to increase the gas pressure any further, and in conventional equipment, the upper limit of the pellet speed was determined at the above pressure. This problem is caused by using the pellet 24 as the boundary of the accelerating gas filling chamber 1l, and cannot be solved by conventional techniques.

Further, in order to advance the adiabatic compression operation of the gas before the pellet 24 starts running, it is necessary to increase the propulsive force of the piston 2. For this reason, conventionally, the gas in the gas reservoir 30 has been sent instantaneously using a rupture disk 3l, etc., but with this method, it is necessary to add a disk for each injection. Pellets need to be fed into the fusion device at a frequency of several Hz,
Repeated injection is not possible with the prior art.

An object of the present invention is to improve the acceleration performance of the pellet 24 by keeping the pellet 24 stationary until the adiabatic compression of the accelerating gas is completely completed. Another object of the present invention is to repeatedly inject pellets. [Means for solving the problem] The above purpose is to provide pellets 24 at the boundary of the accelerating gas filling chamber 11.
This can be achieved by installing a valve that opens and closes at high speed instead.

Further, another object can be achieved by providing the above-mentioned valves and the like and then providing an on-off valve in place of the rupture disk.

[Function] Fig. 5 shows a gas supply device capable of adiabatically compressing pellet accelerating gas and repeatedly injecting pellets.

The accelerating gas filling chamber l1 is provided with an inlet 6 and an outlet 7 for the accelerating gas, and above the outlet 7 is a plunger 9 that can move up and down. Although there is almost no clearance between the plunger 9 and the body 8, and the filling chambers 11 and 12 are spatially connected, the conductance is extremely small. Before the piston 2 moves, the pressure in the filling chamber 11 and the filling chamber 12 is the same.
The plunger 9 is pressed against the outlet 7 by the differential pressure between the pressure of the filling chamber 12 (high pressure) and the outlet 7 (normally vacuum), and closes the outlet 7. When the valve 29 is opened in this state and the high pressure gas 5 is sent into the filling chamber 10, the piston 2 works and the accelerating gas in the filling chamber 11 begins to be adiabatically compressed. By sufficiently increasing the speed of the piston 2, only the gas in the filling chamber 11 is adiabatically compressed. (Since the conductance between the filling chamber 12 and the filling chamber 11 is small, there is almost no adiabatic compression.) When the piston 2 hits the stopper 3 and compression is completed, the valve 13 is opened and the gas in the filling chamber 12 is released. The plunger 9 is suddenly lifted by the compressed high-pressure gas in the filling chamber 1, and the gas in the filling chamber 11 flows out through the outlet 7 to the location where the pellets are located.6 In the present invention, during adiabatic compression of the accelerating gas The pellets never start running. Therefore, piston 2
A normal valve 29 is sufficient as the supply valve for the high pressure gas 5 that provides the propulsive force, and this series of operations can be repeated.

〔Example〕

An embodiment of the present invention will be explained below with reference to FIG. 1st
The figure shows a gas operated valve for supplying pellet gas according to the present invention. The valve has a body 8 having an inlet 6 and an outlet 7 for pellet accelerating gas, and a filling chamber 11, and has a plunger 9 inside for opening and closing the outlet 7. Exit 7 leads to the pellet feeding department. There is a space 12 in the upper part of the plunger 9 filled with gas for pressurizing the plunger 9, which also serves as an operating space for the plunger 9. The accelerating gas filling chamber 11 and the plunger pressurizing gas filling chamber 12 are connected through a gap between the plunger 9 and the body 8, and the conductance in the gap is made very small. A cylinder 1 and a piston 2 are provided on the left side of the body 8 for adiabatically compressing an accelerating gas filling chamber 11.

The operation will be explained below.

Before filling with accelerating gas, gas from the cylinder 5 is first sent to the filling chamber 12 with the gas vent 14 of the valve 13 closed, and the plunger 9 is pressed against the gas outlet 7. Next, the valve 4 is opened to send the accelerating gas, and the filling chamber 11 (volume Vo) is filled with the accelerating gas at the pressure Po and the temperature To. During this filling operation, the plunger 2 in the cylinder 1 slides to the left due to the pressure of the accelerating gas and stops at the stopper 28 position. After filling the accelerating gas, the valve 4 is closed to confine the gas to be adiabatically compressed. Next, with the gas vent 27 of the valve 29 closed, the high pressure gas in the cylinder 5 is sent to the filling chamber 10,
Accelerate plunger 2. By rapidly sliding the plunger 2 to the right, the accelerating gas filling chamber 11 is moved to (4).
Adiabatic compression is performed according to formula and formula (5). The plunger 2 advances to the right while accelerating until the pressure in the filling chamber 10 and the pressure in the filling chamber 11 become equal, and since it continues to have inertia after that, it decelerates and further compresses the filling chamber 11. As a result, when the plunger 2 hits the stopper 3 and stops, the filling chamber 11 can be filled with gas at a high pressure higher than the pressure in the filling chamber 10 and at a high temperature. When the adiabatic compression of the pellet accelerating gas is completed, the gas vent 4 of the valve 13 is opened and the plunger 9 is stopped. The plunger 9 is pushed upward by the pressure of the compressed accelerating gas, and as a result, the outlet 7 opens and the accelerating gas flows through the outlet 7 into the pellet generating section 22 . As a result, the compression ratio of the accelerating gas (V
o/V), formulas (4) and (5
) According to the equation, pellets can be accelerated by high-pressure, high-temperature gas. In addition, in the operation of opening the plunger 9, if the opening/closing time of the valve 14 is changed, the amount of gas flowing out of the filling chamber 12 changes, and as a result, the amount of time that the plunger 9 is open (the filling chamber 1
time until the pressure in the filling chamber 12 becomes equal to the pressure in the filling chamber 12)
can be adjusted, and the amount of gas flowing into the pellet production section 22 can be adjusted. Further, by repeating a series of operations, gas can be repeatedly supplied, and pellets 24 can be repeatedly injected.

Further, other embodiments according to the present invention are shown in FIGS. 6 to 10. FIG. 6 shows the filling chamber 12 and the filling chamber 11 with the plunger 9.
However, no valve is attached to the filling chamber l2. The pressure in the filling chamber 1l rises due to the compression action of the piston 2, and when the force of the gas in the filling chamber 11 pushing up the plunger 9 exceeds the force pushing the plunger 9 with the gas in the filling chamber 12, the valve opens, and otherwise it closes. ing. Fig. 7 shows an embodiment in which a spring 18 is added to Fig. 6 to increase the pressure when the plunger opens and at the same time shorten the opening/closing time. In both cases, the opening/closing operation of the plunger 9 is performed by the filling chamber 11.
FIG. 8 shows a case where an electromagnetic coil 17 is added to the structure shown in FIG. 6 and the plunger 9 is made of a magnetic material.

After the gas compression is completed, the coil 17 is energized to apply a force to pull up the plunger 9 to the gas pressure in the filling chamber 11, thereby enabling high-speed opening and closing operations.

9 and 10 show an embodiment of the method of accelerating the piston 2. FIG. In FIG. 9, the cylinder 5 is filled with a combustible gas such as oxygen or hydrogen, and both gases are mixed in a filling chamber, and the ignition device 2
It explodes at 0 and propels piston 2. Also, the 10th
The figure shows a case where the piston is propelled by exploding the gunpowder 21.

〔Effect of the invention〕

According to the present invention, the pellets are accelerated after the adiabatic compression of the accelerating gas is completely completed, so that the acceleration performance of the pellets is improved compared to the conventional case of incomplete adiabatic compression.

Additionally, adiabatic compression eliminates the need for disposable valves such as rupture disks, which were conventionally required to propel the piston. As a result, a repeating on-off valve can be used instead of a rupture disk or the like, and pellets can be repeatedly injected.

[Brief explanation of drawings]

Fig. 1 is a system diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of a conventional pellet injection device, Fig. 3 is a characteristic diagram showing the time change of accelerating gas pressure, and Fig. 4 is a diagram of the conventional pellet injection device. 5 to 10 are explanatory diagrams of the operation of the pellet injection device, and FIGS. 5 to 10 are explanatory diagrams of the operation of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Cylinder, 2...Piston, 2...Stopper, 4...Valve, 5...Plunger propulsion gas cylinder, 6...Acceleration gas inlet, 7...Acceleration gas outlet, 8
...Body, 9...Plunger, ↓0...Propulsion gas filling chamber, 11...Accelerating gas filling chamber, 12...Plunger pressurizing gas filling 1 Figure 3 Figure 0 'Z' time 71115 force io standing earth '1 hour product - 1 distance is st filling room n'JI force 5111 Figure 6 Figure 4 (b) Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. A pellet accelerating gas supply device consisting of a pellet accelerating gas inlet and outlet, a gas filling chamber, and a cylinder and piston for adiabatically compressing the gas in the filling chamber, comprising: A pellet accelerating gas supply device comprising a plunger that opens and closes, a plunger pressurized gas that controls the operation of the plunger, a filling chamber, and a supply valve for the plunger pressurized gas. 2. The pellet accelerating gas supply device according to claim 1, wherein the pressure and temperature of the pellet accelerating gas are controlled by opening and closing operations of the plunger. 3. In claim 1, the pressure in the chamber filled with the pellet accelerating gas is increased by adiabatic compression, and at the same time, the pressure of the plunger pressurizing gas is decreased to move the plunger away from the gas outlet, and the pellet accelerating gas is A supply device for said pellet accelerating gas to be sent to a gas outlet. 4. The pellet accelerating gas supply device according to claim 1, characterized in that a spring for pressurizing the plunger is provided in place of the plunger pressurizing gas. 5. The pellet accelerating gas supply device according to claim 1, wherein the piston is returned to the position before adiabatic compression by an accelerating gas filling operation, and the pellet accelerating gas can be repeatedly adiabatically compressed and supplied. 6. The pellet accelerating gas supply device according to claim 1, wherein an ignition device is provided in the propellant gas filling chamber of the piston, and the propulsive force is obtained by exploding combustible gas or gunpowder.