JPH0552470B2 - - Google Patents
Info
- Publication number
- JPH0552470B2 JPH0552470B2 JP18094284A JP18094284A JPH0552470B2 JP H0552470 B2 JPH0552470 B2 JP H0552470B2 JP 18094284 A JP18094284 A JP 18094284A JP 18094284 A JP18094284 A JP 18094284A JP H0552470 B2 JPH0552470 B2 JP H0552470B2
- Authority
- JP
- Japan
- Prior art keywords
- coil
- magnetic field
- sample
- frequency
- magnetic permeability
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000035699 permeability Effects 0.000 claims description 33
- 238000005259 measurement Methods 0.000 claims description 23
- 238000001514 detection method Methods 0.000 claims description 16
- 238000013016 damping Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 239000010409 thin film Substances 0.000 description 5
- 238000004804 winding Methods 0.000 description 4
- 239000000696 magnetic material Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
Landscapes
- Measuring Magnetic Variables (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は例えば薄膜磁性材料の高周波に於ける
透磁率の測定に適用して好適な透磁率測定装置に
関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic permeability measuring device suitable for, for example, measuring the magnetic permeability of thin film magnetic materials at high frequencies.
薄膜磁性材料の透磁率を測定する装置の従来例
としては、次の２つがある。その一は、測定用コ
イルに試料を挿入することによるそのインダクタ
ンスの変化をインピーダンスブリツジによつて直
接透磁率を測定するか、Ｑメータのよつて共振周
波数の変化から透磁率を測定するものである。
There are the following two conventional examples of devices for measuring the magnetic permeability of thin film magnetic materials. One method is to directly measure the magnetic permeability by using an impedance bridge to measure the change in inductance caused by inserting a sample into the measurement coil, or to measure the magnetic permeability from the change in resonance frequency using a Q meter. be.
他の一は、略一様な交流磁界を発生する磁界発
生用コイル内に測定用コイルを配し、その測定用
コイル内に試料を挿入し、その測定用コイルの誘
導起電力から透磁率を測定するものである。 The other method is to place a measuring coil inside a magnetic field generating coil that generates a substantially uniform alternating current magnetic field, insert a sample into the measuring coil, and calculate the magnetic permeability from the induced electromotive force in the measuring coil. It is something to be measured.
前者は、測定用コイルの実効容積と、その中に
入れる試料の体積との比（フイリングフアクタ）
の採り方によつて、透磁率の値が変動し、試料に
与える磁界を変化させるのが困難であり、実効透
磁率を得るのが困難であるという欠点がある。 The former is the ratio of the effective volume of the measuring coil to the volume of the sample placed inside it (filling factor).
The value of magnetic permeability varies depending on the method of determining the magnetic field, making it difficult to change the magnetic field applied to the sample, and thus making it difficult to obtain the effective magnetic permeability.
後者は、交流磁界の低域では、磁界の周波数の
測定が困難であるため、その周波数に比例する起
電力から、透磁率を測定するのが困難であり、高
域では、測定用コイルの自己インダクタンス及び
浮遊容量によつて共振が生じ、交流磁界の周波数
がその共振周波数付近にある場合は誘導起電力か
らインダクタンスを測定することができなかつ
た。 The latter is because in the low range of an alternating magnetic field, it is difficult to measure the frequency of the magnetic field, so it is difficult to measure the magnetic permeability from the electromotive force proportional to the frequency. Resonance occurs due to inductance and stray capacitance, and when the frequency of the alternating magnetic field is around the resonance frequency, it is not possible to measure inductance from the induced electromotive force.
かかる点に鑑み本発明は、容易且つ高精度に試
料の透磁率を測定することのできる透磁率測定装
置を提案しようとするものである。 In view of this point, the present invention proposes a magnetic permeability measuring device that can easily and accurately measure the magnetic permeability of a sample.
本発明による透磁率測定装置は、略一様な交流
磁界を発生する磁界発生用コイル１と、この磁界
発生用コイル１中に配された磁界検出用コイル３
及び試料を挿入しない状態で出力電圧が略零とな
された測定用差動コイル４とを有し、この測定用
差動コイル４の、その一方のコイル部４ａに試料
７を挿入したときの出力電圧と、検出コイル３の
出力電圧との比から試料７の透磁率を測定するよ
うにするものである。
The magnetic permeability measuring device according to the present invention includes a magnetic field generating coil 1 that generates a substantially uniform alternating current magnetic field, and a magnetic field detecting coil 3 disposed within the magnetic field generating coil 1.
and a measurement differential coil 4 whose output voltage is approximately zero when no sample is inserted, and the output when the sample 7 is inserted into one coil portion 4a of the measurement differential coil 4. The magnetic permeability of the sample 7 is measured from the ratio of the voltage to the output voltage of the detection coil 3.
上述せる本発明によれば、磁界発生用コイル１
よりの略一様な交流磁界が、この磁界発生用コイ
ル１中に配された磁界検出用コイル３及び常態に
於いて出力電圧が略零となされた測定用差動コイ
ル４に与えられ、この測定用差動コイル４の、そ
の一方のコイル部４ａに試料７を挿入したときの
出力電圧と、検出コイル３の出力電圧との比から
試料７の透磁率を測定することができる。
According to the present invention described above, the magnetic field generating coil 1
A substantially uniform alternating current magnetic field is applied to the magnetic field detecting coil 3 disposed in the magnetic field generating coil 1 and the measuring differential coil 4 whose output voltage is approximately zero under normal conditions. The magnetic permeability of the sample 7 can be measured from the ratio of the output voltage of the detection coil 3 to the output voltage when the sample 7 is inserted into one coil portion 4a of the measurement differential coil 4.
以下に、第１図〜第３図を参照して、本発明の
一実施例を詳細に説明する。１は磁界発生用の、
断面が短形の帯状コイルで、これに交流電源２が
接続されて、コイル１の中央部に於いて、コイル
１の各面に平行な略一様な交流磁界HAC＝−Hp
cos（ωt）が発生する。３は磁界検出用コイル、
４は測定用差動コイルである。測定用差動コイル
４は有効面積が互いに等しい２つのコイル部４
ａ，４ｂから成る。
An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3. 1 is for magnetic field generation,
It is a strip-shaped coil with a rectangular cross section, to which an AC power source 2 is connected, and at the center of the coil 1, an approximately uniform AC magnetic field parallel to each surface of the coil 1 H AC =-H p
cos(ωt) occurs. 3 is a magnetic field detection coil;
4 is a differential coil for measurement. The measurement differential coil 4 has two coil parts 4 with equal effective areas.
It consists of a and 4b.
磁界検出用コイル３は、５mm×30mmのアクリル
製の巻枠に直径が0.2mmの銅線を巻装して構成し
たもので、Ｑダンピング用の高周波抵抗器（例え
ば100Ω）５が挿入されている。測定用差動コイ
ル４は、10mm×30mmのアクリル製の巻枠に直径が
0.2mmの銅線を巻装して構成したもので、各コイ
ル部４ａ，４ｂに夫々Ｑダンピング用の高周波抵
抗器（例えば夫々200Ω）６ａ，６ｂが挿入され
る。 The magnetic field detection coil 3 is constructed by winding a copper wire with a diameter of 0.2 mm around a 5 mm x 30 mm acrylic winding frame, and a high frequency resistor (for example, 100Ω) 5 for Q damping is inserted. There is. The measurement differential coil 4 is a 10 mm x 30 mm acrylic winding frame with a diameter of
It is constructed by winding a 0.2 mm copper wire, and Q damping high frequency resistors (for example, 200Ω each) 6a and 6b are inserted into each coil portion 4a and 4b, respectively.
そして、これらコイル３，４を、その面が磁界
発生用コイル１の交流磁界HACに対し例えば垂直
になるように、コイル１の中央部に配する。この
場合、測定用差動コイル４の一方のコイル部４ａ
に試料７を挿入するとき、この試料７の挿入の邪
魔にならない位置に磁界検出用コイル３を配する
ようにする。 These coils 3 and 4 are arranged at the center of the coil 1 so that their surfaces are, for example, perpendicular to the alternating current magnetic field H AC of the magnetic field generating coil 1. In this case, one coil portion 4a of the measurement differential coil 4
When inserting the sample 7 into the sample 7, the magnetic field detection coil 3 is placed at a position where it does not interfere with the insertion of the sample 7.
この試料７は、例えば幅４mm、厚さ４mmの、ス
パツタ法によつて作製したFeCO、SiB系アモル
フアス薄膜（試料）及び幅１mm、厚さ16μｍの
同様な組成の液体急冷法で作製したアモルフアス
薄帯（試料）である。 Sample 7 includes, for example, an FeCO, SiB-based amorphous thin film (sample) with a width of 4 mm and a thickness of 4 mm prepared by the sputtering method, and an amorphous amorphous thin film (sample) of a similar composition with a width of 1 mm and a thickness of 16 μm prepared by the liquid quenching method. It is a strip (sample).
次に測定の手順を説明する。測定用差動コイル
４の誘導起電力による差動出力電圧が零となるよ
うに、磁界発生用コイル１内で測定用差動コイル
４の位置を可変する。次に、測定用差動コイル４
一方のコイル部４ａに試料７を挿入する。そし
て、磁界検出用コイル３及び測定用差動コイル４
の誘導起電力による各出力電圧を測定する。 Next, the measurement procedure will be explained. The position of the measuring differential coil 4 is varied within the magnetic field generating coil 1 so that the differential output voltage due to the induced electromotive force of the measuring differential coil 4 becomes zero. Next, the measurement differential coil 4
A sample 7 is inserted into one coil portion 4a. Then, a magnetic field detection coil 3 and a measurement differential coil 4
Measure each output voltage due to the induced electromotive force.
この場合、磁界検出用コイル３及び測定用差動
コイル４の出力電圧は夫々次式のように表わされ
る。 In this case, the output voltages of the magnetic field detection coil 3 and the measurement differential coil 4 are expressed by the following equations, respectively.
V3＝μpS3ωHpsin（ωt） ……(1)
V4＝μpμrS7ωHpsin（ωt） ……(2)
ここで、S3は磁界検出用コイル３の有効面積、
μrは試料７の比透磁率、S7は試料７の断面積であ
る。 V 3 = μ p S 3 ωH p sin (ωt) ...(1) V 4 = μ p μ r S 7 ωH p sin (ωt) ...(2) Here, S 3 is the value of the magnetic field detection coil 3. effective area,
μ r is the relative magnetic permeability of sample 7, and S 7 is the cross-sectional area of sample 7.
かくして、出力電圧V3及びV4を測定し、その
比V4／V3を採れば、
V4／V3＝μr（S7／S3） ……(3)
が求められる。(3)式から、
μr＝（V4／V3）／（S7／S3） ……(4)
が得られ、これから試料７の比透磁率μrを算出す
ることができる。 Thus, by measuring the output voltages V 3 and V 4 and taking their ratio V 4 /V 3 , the following can be obtained: V 4 /V 3 = μ r (S 7 /S 3 ) (3). From equation (3), μ r =(V 4 /V 3 )/(S 7 /S 3 ) (4) is obtained, and the relative magnetic permeability μ r of sample 7 can be calculated from this.
尚、出力電圧V3、V4は共に交流磁界HACの角
周波数ωに比例するから、角周波数ωが低くなれ
ばなく程、出力電圧V3、V4の測定精度が低下し、
試料７の比透磁率μrの精度が低下する。そこで、
出力電圧V3、V4を、第４図に特性を示す如く利
得が周波数の逆数に比例する各別の増幅器に夫々
供給し、その出力電圧を測定すれば交流磁界HAC
の角周波数に殆んど無関係に、試料７の透磁率を
高精度で測定することができる。 Note that since both the output voltages V 3 and V 4 are proportional to the angular frequency ω of the alternating current magnetic field H AC , the lower the angular frequency ω, the lower the measurement accuracy of the output voltages V 3 and V 4 .
The accuracy of the relative magnetic permeability μ r of sample 7 decreases. Therefore,
If the output voltages V 3 and V 4 are respectively supplied to separate amplifiers whose gains are proportional to the reciprocal of the frequency as shown in FIG. 4, and the output voltages are measured, the alternating current magnetic field H AC
The magnetic permeability of the sample 7 can be measured with high precision almost independently of the angular frequency.
次に、磁界検出用コイル３及び測定用差動コイ
ル４にＱダンピング用抵抗器５；６ａ，６ｂを挿
入しない場合と、挿入した場合との交流磁界の周
波数に対する出力電圧の特性を、第５図及び第６
図に示す。第５図は磁界検出用コイル３の特性を
示し、実線は抵抗器５を挿入しない場合、破線は
抵抗器５を挿入した場合の特性を夫々示し、実線
の場合は25MHz付近に共振による出力電圧のピー
クがあるが、破線の場合はこのピークが消失し、
出力電圧の周波数特性が平坦になつている。 Next, the characteristics of the output voltage with respect to the frequency of the alternating magnetic field when the Q damping resistors 5; 6a and 6b are not inserted into the magnetic field detection coil 3 and the measurement differential coil 4 and when they are inserted are shown in the fifth section. Figure and 6th
As shown in the figure. Figure 5 shows the characteristics of the magnetic field detection coil 3, where the solid line shows the characteristics when the resistor 5 is not inserted, and the broken line shows the characteristics when the resistor 5 is inserted.The solid line shows the output voltage due to resonance around 25MHz. There is a peak, but in the case of the broken line, this peak disappears,
The frequency characteristics of the output voltage are flat.
第６図は測定用コイル４の特性を示し、実線は
抵抗器６ａ，６ｂを挿入しない場合、破線は抵抗
器６ａ，６ｂを挿入した場合の特性を夫々示し、
実線の場合は21MHz付近に共振よる出力電圧のピ
ークがあるが、破線の場合はこのピームが消失
し、出力電圧の周波数特性が平坦になつている。 FIG. 6 shows the characteristics of the measuring coil 4, where the solid line shows the characteristics when the resistors 6a and 6b are not inserted, and the broken line shows the characteristics when the resistors 6a and 6b are inserted, respectively.
In the case of the solid line, there is a peak of the output voltage due to resonance around 21MHz, but in the case of the broken line, this peak disappears and the frequency characteristics of the output voltage become flat.
従つて、交流磁界の周波数がピーク時周波数か
ら離れている場合は、コイル３，４対するＱダン
ピング用抵抗器５；６ａ，６ｂの挿入の有無は任
意であるが、ピーク時周波数付近の場合はコイル
３，４にＱダンピング用抵抗器５；６ａ，６ｂを
挿入する必要がある。 Therefore, when the frequency of the AC magnetic field is far from the peak frequency, it is optional whether or not to insert the Q damping resistors 5; 6a and 6b for the coils 3 and 4, but when the frequency is near the peak frequency, It is necessary to insert Q damping resistors 5; 6a and 6b into the coils 3 and 4.
第７図に、磁界検出コイル３の出力側に、第４
図に示す如く利得が周波数の逆数に比例する増幅
器を接続した場合と、しない場合の出力電圧の周
波数特性を夫々実線及び破線にて示す。これによ
れば、実線では周波数の上昇に従つて、出力電圧
が上昇するが、破線の場合は出力電圧の周波数特
性は平坦となり、交流磁界の周波数がかなり低く
ても、試料７の透磁率の測定が可能であることが
分る。 In FIG. 7, a fourth
As shown in the figure, the frequency characteristics of the output voltage are shown by solid lines and broken lines, respectively, when an amplifier whose gain is proportional to the reciprocal of the frequency is connected and when it is not connected. According to this, in the case of the solid line, the output voltage increases as the frequency increases, but in the case of the broken line, the frequency characteristics of the output voltage are flat, and even if the frequency of the alternating magnetic field is quite low, the permeability of sample 7 It turns out that measurement is possible.
第８図に上述の試料及びの実効透磁率の測
定結果を示し、夫々実効透磁率が周波数依存性を
有していることが分る。 FIG. 8 shows the measurement results of the effective magnetic permeability of the above-mentioned samples, and it can be seen that the effective magnetic permeability of each sample has frequency dependence.
上述の実施例によれば、500kHz〜110MHzの周
波数の磁界に於ける試料の透磁率を測定すること
ができる。 According to the embodiment described above, it is possible to measure the magnetic permeability of a sample in a magnetic field with a frequency of 500 kHz to 110 MHz.
上述せる本発明によれば、容易且つ高精度に試
料の透磁率を測定することのできる透磁率測定装
置を得ることができる。
According to the present invention described above, it is possible to obtain a magnetic permeability measuring device that can easily and accurately measure the magnetic permeability of a sample.
上述した試料の如き薄膜軟磁性材料の断面積は
数μｍ×数mm程度であるため、その透磁率を正確
に測定するためには、例えば、100MHz程度の高
周波数の交流磁界を磁界発生用コイルから発生さ
せる必要がある。従つて、本発明によれば、この
ような高周波交流磁界の下に試料の透磁率を測定
する場合に、試料の透磁率の測定前における出力
を略零にして、正確な透磁率の測定を可能にした
ものである。 The cross-sectional area of a thin film soft magnetic material such as the sample mentioned above is approximately several μm x several mm, so in order to accurately measure its magnetic permeability, it is necessary to apply an alternating current magnetic field at a high frequency of approximately 100 MHz to a magnetic field generating coil. It needs to be generated from. Therefore, according to the present invention, when measuring the magnetic permeability of a sample under such a high-frequency alternating magnetic field, the output before measuring the magnetic permeability of the sample is set to approximately zero to ensure accurate measurement of the magnetic permeability. It made it possible.
又、磁界検出用コイル及び測定用差動コイルに
Ｑダンピング用抵抗器を挿入することにより、両
出力電圧の共振周波数付近に於けるピークの発生
による測定透磁率の誤差の発生を回避することが
できる。 In addition, by inserting a Q-damping resistor into the magnetic field detection coil and the measurement differential coil, it is possible to avoid errors in the measured magnetic permeability due to peaks near the resonance frequency of both output voltages. can.
又、磁界検出用コイル及び測定用コイルの出力
側に、夫々利得が周波数の逆数に比例する増幅器
を接続することにより、交流磁界の周波数が低く
ても透磁率の測定を高精度に行なうことができ
る。 Furthermore, by connecting amplifiers whose gains are proportional to the reciprocal of the frequency to the output sides of the magnetic field detection coil and measurement coil, magnetic permeability can be measured with high precision even when the frequency of the alternating magnetic field is low. can.
第１図は本発明による透磁率測定装置の一実施
例を示す斜視図、第２図及び第３図はその磁界検
出用コイル及び測定用差動コイルを示す側面図、
第４図〜第８図は本発明の説明に供する特性曲線
図である。
１は交流磁界発生用コイル、２は交流電源、３
は磁界検出用コイル、４は測定用差動コイルであ
る。
FIG. 1 is a perspective view showing an embodiment of a magnetic permeability measuring device according to the present invention, FIGS. 2 and 3 are side views showing a magnetic field detection coil and a measuring differential coil thereof,
4 to 8 are characteristic curve diagrams for explaining the present invention. 1 is a coil for generating an AC magnetic field, 2 is an AC power source, 3
4 is a magnetic field detection coil, and 4 is a measurement differential coil.
Claims (1)
ルと、該磁界発生用コイル中に配された磁界検出
用コイル及び試料を挿入しない状態で出力電圧が
略零となされた測定用差動コイルとを有し、該測
定用差動コイルの、その一方のコイル部に試料を
挿入したときの出力電圧と、上記検出コイルの出
力電圧との比から上記試料の透磁率を得るように
したことを特徴とする透磁率測定装置。1. A magnetic field generation coil that generates a substantially uniform alternating current magnetic field, a magnetic field detection coil disposed within the magnetic field generation coil, and a measurement differential coil whose output voltage is approximately zero when no sample is inserted. and the magnetic permeability of the sample is obtained from the ratio of the output voltage when the sample is inserted into one coil portion of the measurement differential coil and the output voltage of the detection coil. A magnetic permeability measurement device featuring:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18094284A JPS6157871A (en) | 1984-08-30 | 1984-08-30 | Measuring instrument for magnetic permeability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18094284A JPS6157871A (en) | 1984-08-30 | 1984-08-30 | Measuring instrument for magnetic permeability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6157871A JPS6157871A (en) | 1986-03-24 |
| JPH0552470B2 true JPH0552470B2 (en) | 1993-08-05 |
Family
ID=16091968
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18094284A Granted JPS6157871A (en) | 1984-08-30 | 1984-08-30 | Measuring instrument for magnetic permeability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6157871A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0727016B2 (en) * | 1990-05-14 | 1995-03-29 | 日本放送協会 | Permeability measuring device and measuring method |
| JP6960655B2 (en) * | 2017-03-31 | 2021-11-05 | 国立大学法人 筑波大学 | Magnetic property measurement method for magnetic materials and magnetic property measurement device for magnetic materials |
-
1984
- 1984-08-30 JP JP18094284A patent/JPS6157871A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6157871A (en) | 1986-03-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3246727B2 (en) | Inductive electronic caliper | |
| RU2104478C1 (en) | Method of contactless dynamic measurement of displacement of grounded conductive body | |
| US2933677A (en) | Probe for a thickness testing gage | |
| US4430615A (en) | Reflection type probes for eddy current testing instruments | |
| JPS63109338A (en) | Device for electrically measuring torque in shaft indirectly in noncontact manner | |
| JPH08273952A (en) | Plane current detector | |
| US5847562A (en) | Thickness gauging of single-layer conductive materials with two-point non linear calibration algorithm | |
| US7576532B2 (en) | Motion transducer for motion related to the direction of the axis of an eddy-current displacement sensor | |
| JPH0552470B2 (en) | ||
| JP2006343336A (en) | Nonoptical reading for test area | |
| JPH056641B2 (en) | ||
| Saxena et al. | Capacitive moisture meter | |
| JP2000028695A (en) | Method and apparatus for measurement of magnetism | |
| JP2022055415A (en) | Magnetic field detection element | |
| JP3607447B2 (en) | Magnetic field sensor | |
| JP3144871B2 (en) | Permeability measuring device | |
| RU2115115C1 (en) | Process of detection of gas-saturated layers on titanium alloys and device for its implementation | |
| JPH0727016B2 (en) | Permeability measuring device and measuring method | |
| RU2490611C1 (en) | Device to measure pressure inside pipelines made of ferromagnetics | |
| JP2637032B2 (en) | Permeability measurement method | |
| SU721737A1 (en) | Device for eddy-current inspection of conducting media | |
| JP2509207Y2 (en) | Eddy current flaw detector | |
| JPH07104043A (en) | Magnetometric sensor | |
| JPH10328152A (en) | Electromagnetic rheometer | |
| US3493851A (en) | Vibration magnetometer for measuring tangential component of magnetic field on flat surface of ferromagnetic samples |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |