JPH0156520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray generator used in various analytical devices.

The X-ray generator consists of an anode and a cathode filament, and the surface of the anode gradually becomes contaminated during use due to deposition of cathode filament material or adhesion of residual gas inside the X-ray generator, resulting in a decrease in X-ray output. I'll come. A decrease in X-ray output appears as a decrease in the sensitivity of an analyzer that uses X-rays. If the X-ray generator is an open tube, it is possible to disassemble the analyzer and clean the anode surface of the X-ray generator, but in practice,
Such work is extremely complicated.

Therefore, the present invention is an analyzer that uses X-rays, and the X-ray generator can be operated only from the outside while it is attached to the analyzer, without having to disassemble the analyzer and take out the X-ray generator. The purpose of this invention was to obtain an X-ray generator in which the anode of the X-ray generator can be purified by the method.

In the present invention, a grid is provided around the cathode filament, and by switching, the anode can be applied with either a negative high voltage or a positive high voltage, and the grid can be applied with a positive voltage to the cathode filament. The present invention provides an X-ray generating device in which an ion generating gas can be introduced into the device and the anode can be cleaned by ion bombardment. The present invention will be explained below with reference to Examples.

The figure shows an embodiment in which the present invention is applied to an X-ray photoelectron analyzer. Reference numeral 1 denotes a main vacuum vessel of the analyzer, to which an exhaust system 2 is connected. A portion 3 surrounded by a dotted line within the main body 1 is an X-ray generator. The dotted line is a convenient means on the drawing to indicate the entire X-ray generator and does not specifically exist. The X-ray generator consists of an anode A, a cathode filament F, and a Wehnelt electrode W.
and a filter plate S, and a grid G and a repeller plate R provided surrounding the cathode filament F.
It's getting more familiar. Here, the grid G and the repeller plate R are unique to the present invention. A sample 4 is irradiated with X-rays emitted from anode A.
Photoelectrons emitted from the sample 4 by X-ray irradiation enter an electron energy analyzer 5, are sorted by kinetic energy, enter a detector 6, and are detected. 7 is a recorder that records the output of the detector 6 with energy on the horizontal axis. 9 is a tube for introducing ionizing gas into the main body 1, and 10 is a valve provided on the tube 9.

Reference numeral 8 denotes a power supply device for the X-ray generator, which includes a high-voltage power supply Px for generating X-rays, a power supply Pf for heating the cathode filament F, and a power supply Pg for the grid G. The high voltage power supply Px for generating X-rays has a positive terminal a and a negative terminal b, the positive terminal outputs a positive voltage of 0 to several tens of KV, and the negative terminal outputs a negative voltage of 0 to several tens of KV. . Either the positive or negative voltage of these high voltages is applied to the anode A by a changeover switch Sw1. The grid power supply Pg generates a positive voltage of 0 to several hundred V,
The voltage is applied to the grid G by connecting the changeover switch SW2 to the contact c side. /Switch
Sw1 and Sw2 are linked, and Sw1 is connected to terminal a.
When Sw1 is brought into contact with terminal b, Sw2 is brought into contact with the contact d side, and when Sw1 is brought into contact with terminal b, Sw2 is brought into contact with the contact c side. When generating X-rays, switch SW1 is set to the terminal a side and switch SW2 is set to the contact d side. At this time, a positive high voltage is applied to the anode A, and the electrons emitted from the filament F collide with the anode A, following a trajectory approximately as shown in the figure e. In this embodiment, the grid G is currently grounded through a high resistance r, and the hot electrons emitted from the filament F adhere thereto, resulting in a negative potential, which itself acts as a Wehnelt electrode.

When cleaning the anode, switch Sw1
switch to the terminal b side, and switch Sw2 to the contact c side. In this way, the grid G will be several 100V
becomes a positive potential, and the anode A becomes a negative high potential.
The filament F, together with the Wehnelt electrode W and the repeller plate R, is at 0 potential (the filament is 2 to 3 V higher on average than the Wehnelt and repeller), and the thermoelectrons emitted from the filament F are at the grid G.
Some of it is absorbed by grid G, but most of it passes through grid G, reaches near Wehnelt W and repeller R, and is reflected. In this way, the electrons gradually flow into the grid G while reciprocating vibration between the filament F, Wehnelt W, and repeller R. On the other hand, in the case of anode cleaning, the valve 10 is opened to introduce the ionizing rare gas into the main body 1 (the exhaust system 2 is left in operation). The introduced gas molecules collide with electrons vibrating between the filament F, Wehnelt W, and repeller R, and are ionized. In this case, since the electrons are reciprocating, there is an increased chance of ionization even if the pressure within the main body 1 of the introduced gas is low. Most ions are generated around grid G, and grid G serves as an ion optical ion source. If the pressure of the introduced gas is too high, excessive ions will be generated and a sheath will be formed around the filament F, which is rather undesirable. A suitable pressure within the body 1 of the introduced gas is on the order of 10 ^-5 torr. As described above, the ion source can be regarded as a grid G from an ion optical perspective. This has the following meaning. X
When a line is generated, the grid G has a negative potential due to the attachment of electrons, and the electrons that fly out from the filament F with a certain initial velocity distribution accumulate around the grid G, forming a space charge there. becomes a potential valley and becomes an electro-optical electron beam source. Therefore, X
The positions of the electron beam source during beam generation and the ion source during anode cleaning are the same. Therefore, when a voltage with the same absolute value and negative polarity as when X-rays are generated is applied to anode A, the ions follow approximately the same orbit as the electrons, and the ions collide with the anode at the same position as the electrons when X-rays are generated. Become. Cleaning of the anode relies on the etching action of the anode surface caused by ion bombardment, so by selectively etching the areas where X-rays are actually generated, the anode can be cleaned efficiently. It turns out.

Structurally, the X-ray generator of the present invention has a grid around the cathode so that a positive voltage can be applied, and high positive and negative voltages can be applied to the anode, and ionizing gas can be introduced into the main vacuum container. The structure is less complicated than conventional X-ray generators, and the anode can be cleaned by simply switching a switch and operating a valve.
Compared to the method of disassembling the device one by one and polishing the anode, the cleaning work is significantly simplified and streamlined.

[Brief explanation of drawings]

The drawing is a longitudinal sectional side view of an apparatus according to an embodiment of the present invention. 1...Main vacuum vessel, 2...Exhaust system, 3...X-ray source,
4... Sample, 5... Electron energy analyzer, 6... Detector, 7... Recorder, 8... X-ray generator power supply, 9... Ionization gas introduction tube, A... Anode, F... Cathode filament, S... Filter, W...Wehnelt electrode, R...repeller plate, G...grid.

Claims (1)

[Claims] 1 A tube capable of optionally introducing ionizing gas is provided in the main body vacuum container connected to the exhaust system, and an anode and a cathode filament are provided in the main body, a Wehnelt electrode provided between the anode and the cathode filament, and a cathode filament. and a grid provided between the Wehnelt electrode and the X-ray generating section,
A high-voltage power supply capable of arbitrarily switching and applying positive and negative voltages to the anode, a filament power supply, and a power supply applying a positive voltage to the grid via a switch that is turned on when negative high voltage is applied to the anode. Line generator.