The extractor principle seems to be the most useful principle for the measurement of xhv. Even simple extractor systems are able to discriminate between ions generated in the gas phase and ESD ions produced at the grid surface. According to our calculations the modified extractor gauge developed in our institute is less influenced by ESD ions than the extractor gauge suggested by Redhead. By experiments was demonstrated, that a gold coating of the anode reduces the ESD effect too.
In the case of an extractor gauge the light of the hot filament gauge has a small influence on the ion current in the xhv range. The influence of the vapor pressure of the cathode material on the ion current can be reduced by the use of activated cathodes operating at low temperatures. These results were obtained experimentally.
Topics of a further development are the problems of the reduction of the outgassing rate and the fast and convinient measurement of extremely low ion currents. The use of electron multipliers complicates the degassing process and the electronicequipment for the measurement of these low ion currents.

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This Paper describes the fablication of AlN tin films containing iron and iron nitride particles, and magnetic and electrical properties of such films. Fe-N-Al alloy films were deposited in Ar and N₂ mixtures at ambient temperature using Fe/Al composite targets in a two-facing-target DC sputtering chamber. X-ray diffraction results showed that the Fe-N-Al films were amorphous, and after annerling for 5 h both AlN and bcc-Fe/bct-FeN_x phases appeared. Structure changes in the FeN_x phases were explained in terms of occupied nitrogen atoms. Electron diffraction and transmission electron microscopy observations revealed that iron and iron nitride particles were randomly dispersed in annealed AlN films. The grain size of magnetic particles ranged from 5 to 20 nm in diameter depending on annealing conditions. Saturation magnetization (0.75-1.41T) and high electrical resistivity (46-6.5μΩm) were obtained in annealed AlN thin films containing randomly dispersed iron/iron nitride particles with 36 to 69 at%Fe.

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In order to develop an ion gauge with a very low outgassing rate and a very low gas sorption rate, we have been studying in the electron oscillator mini-ion gauge with a ring anode since the early 80's. We have published a handful of paper on our achievements in Vacuum Science and Technology (China). I planned to attend the 28th AVS to present our paper but plan did not come true due to financial difficulties.
In the latter part of 1983, we invited about 30 distinguished Chinese experts in vacuum measurement to attend a special meeting, we devoted to discussion of the electron oscillator mini-ion-gauge. As a result, we believe Chinese researchers in this field are familiar with each others' work.
We were surprised to read the paper by Suen et al. which was presented at XHV '94. We were especially surprised to learn that “a new mini-axial-emission ionization gauge (MAEG) with a ring anode, which is a modification of the AEG and the oscillator mini-ion-gauge (OMG), is described in this paper.” and “The original plate collector and spiral grid of AEG are replaced by a needle (0.15×5mm, W) and a ring anode (0.2×6mm, Mo), respectively.”
We would like to emphasize that the “new” ionization gauge presented by Suen et al. bears close similarity to the gauge described in papers we presented in 1984. The only differences are minor : for example, Suen et al. choose different operating voltages and electrode materials. Hence it is our conviction that the ion gauge presented by Suen et al. is not a new gauge.

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My reply to the statment of Chen Pijin is as follows
1. In order to develop the XHV measurement, we (Y. H. Kuo at Beijing University, J. Z. Chen at Shanghai Lamp Factory and I) have been conducting research on the axial-emission ionazation gauge since the end of the 70's. Based on the axial-emission ionization gauge (AEG), five kinds of modified AEG have been developed. We have published many papers describing our achievements in IVC-9, IVC-10, IVC-11, IVC-12 and in J. Vac. Sci. & Technol. (USA), Vacuum (UK) and J. Vac. Soc. Jpn from 1982 to 1992, most of which are cited in “Mini-Axial-emission Ionization Gauge with a Ring Anode” as referneces.
2. In order to realize smaller dimensions and simpler construction of AEG for UHV and XHV measurements, the mini-axial-emission ionization gauge with a ring anode was developed. It is a modification of the AEG and the oscillator mini-ion gauge (OMG) which was developled by Chen Pijin et al. Thus, Chen's paper is cited in our paper.
3. We fabricated six mini-axial-emission ionization gauges with a ring anode (MAEG) as sample gauges for our initial experiment. According to our results we wrote this paper. We describe the results of the above mentioned experiment in our paper. After our paper was published, we learned of another paper Chen Pijing. “Prospects on the electron oscillator mini-ion-gauge with a ring anode”. In this paper, there are two brief schematic construction diagrams which are similar to MAEG, but there are no experimental curves or detailed data. If we had known of this study prior to publication of our own, we would have cited it as a reference.
4. Our gauge differs in construction, materials and electrical parameters from Chen Pijin's gauge, as shown in the following table.

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