JPS5989762A - Power source for lab6 cathode for ion plating - Google Patents

Abstract

PURPOSE:To minimize the power loss due to series resistance and to improve the power efficiency in electric discharge with an LaB6 cathode for ion plating by carrying out the discharge using three power sources. CONSTITUTION:Gaseous discharge with an LaB6 cathode is carried out using a variable power source PT for applying a high-voltage current of low intensity at the beginning of discharge, a power source PH for applying a medium-voltage current of medium intensity in a cathode heating stage, and a power source PO for applying a low-voltage current of high intensity during stationary arc discharge. The changeover of the three power sources PT, PH, PO can be automated by utilizing diodes 7. Thus, discharge can be stabilized against a change of a discharge electrode with age.

Description

[Detailed description of the invention] Patent application (
54-057f395 and 56-172888) La
When performing gas discharge using a B6 cathode, there are eight discharge stages: glow discharge (discharge start), quasi-steady arc discharge (cathode heating), and steady arc discharge (large current discharge). First, the initial discharge initiation stage requires a high voltage (~600V) as determined by Paschen's law, but a small current (<0.5A) is required and the first cathode heating stage requires an intermediate voltage (~200V). ) and intermediate current (~15A). In order to smoothly perform ion plating in the final stage of steady arc discharge, the discharge pressure must be 150A or more, and the discharge pressure must be too much.
It is necessary before and after (depending on the type of gas). If these three stages are performed with one power supply and the voltage is dropped by a series resistor,
Power loss becomes significantly large, power efficiency deteriorates, and power supply costs also increase. Therefore, if you use a triple source system as shown in the drawing, that is, if you use a high voltage, low current power source (P,), an intermediate voltage, intermediate current power source (PH), and a low voltage, large current power source (P,), the power will be generated by the series resistance. Power efficiency can be increased by minimizing losses. Further, if diodes are used as shown in Figure 9, the transition of the triple source can be performed automatically.

The next important thing is the relationship between the secular change of the discharge electrodes, including the cathode, and the transition from the start of discharge to a quasi-steady arc. Empirically, when the discharge electrode is new, the surface is rough and the electric field is strong, so the transition is easy, and the transition is easy. is 500V,
About 10 mA is sufficient. However, if a large current discharge is performed for a long time, the surface roughness disappears and the initial electric field becomes small, so the transition from the start of discharge to the cathode heating stage is 0.5
There may be cases where it is necessary to increase the current to about A (although it is better to keep the current at the initial stage as small as possible in order to minimize damage to the cathode). Another feature of this power supply is that, as described above, measures have been taken to transition from the start of discharge to the cathode heating stage in response to secular changes in the discharge electrodes. In other words, P in one drawing
.

The voltage and current are variable.

[Brief explanation of the drawing]

The drawing shows the t of L a B 6 cathode for ion plating:
FIG. 3 is a diagram showing the principle circuit of the power source and the connection to the discharge electrodes. In the drawing, 1 is a variable high-voltage, low-current power supply (PT) for starting discharge. 2
is an intermediate voltage intermediate current power supply (PH) for cathode heating. 3 is a low voltage, large current power supply (Po) for steady large current discharge. 4 is a variable resistor. 5 is a fixed resistance. 6 is a large variable resistor. 7 is a diode. 8 and 9 are discharge intermediate electrode load resistances. lO is L a B 6 cathode. 11 is a first intermediate electrode. 12 is a second intermediate electrode. 13 is a discharge anode and ion plating hearth. 14 is a discharge start switch (on for several seconds or less);

Claims (1)

[Claims] Patent applications (54-057895 and 56-172388)
Regarding the discharge of the L a B 6 cathodes, this power supply has a triple source configuration to increase power efficiency, and also takes measures to stabilize the discharge according to secular changes in the discharge electrodes.