◆ElectroMagneric Flux Compression system (電磁濃縮法：磁場発生装置 5MJ, 2MJ)
custom made by L-3 communications
The ultra-high magnetic field up to 730 T can be generated by the ElectroMagneric Flux Compression (EMFC) system [1].
There, a metallic cylinder called the "liner" is subjected to the inductive electromagnetic force from a main(primary) coil, and the initial(seed) magnetic field of around 4 T is compressed by an imploding liner within a few microseconds before the magnet coil destruction.
The energy injected to the main coil is stored in the fast main condenser bank.
Several types of magneto-optical measurements (Faraday rotation, streak spectroscopy) can be performed under the low temperature of 5 K.
The sample are also destroyed by the explosion just after the magnetic field generation.
In 2014, 5MJ system (left) and 2MJ system (right) was installed for the higher peak magnetic field generation and theapplication for solid state physics measurements above 300 T.
◆Main condenser bank of the EMFC system (電磁濃縮法：主バンク)
custom made by L-3 communications
The fast condenser bank used for the EMFC system. 5MJ system has 10 modules of 0.5 MJ condenser bank unit, which connects to the load coil in parallel. 2MJ system has 4 modules of the same unit to the 5 MJ system.
The maximum charging voltage is 50 kV, and the rated current is 7 MA (5 MJ system).
For discharging the condenser banks, one air-gap switch is used per 0.5 MJ condenser bank unit.
◆Seed condenser bank of the EMFC system (電磁濃縮法：副バンク)
custom made by L-3 communications
The condenser bank unit for the seed field coil. The maximum stored energy is 2.0 MJ and the maximum charging voltage is 20 kV. For the switch to discharge the condenser, the two ignitrons are used per 0.5 MJ unit.
◆Main condenser bank of the old EMFC system (電磁濃縮法：旧式主バンク)
custom made by Nichicon
The old main condenser bank for the EMFC system had also the maximum stored energy of 5 MJ.
For the installation of the new condenser bank system, old condenser bank units were partly removed and 2 MJ units are remained now.
By using 12 air-gap switches are used per 0.5 MJ condenser bank unit in parallel, the residual impedance is reduced.
In case of 5 MJ discharging, the high voltage trigger (80 kV) from the master gap switch branches to ten sub-master gap switch, then 120 air-gap switches are synchronously triggered.
◆Control console of the EMFC system (電磁濃縮法：制御盤)
custom made by L-3 communications
The control console of the EMFC system is settled in the shield room, where is separated about 5 m from the anti-explosion box.
The condenser bank and the pneumatic pressure for the air-gap switch are controlled.
The consoles for the seed bank (right) and the main bank (left: 5MJ system, middle: 2MJ system) are enabled to synchronously trigger.
◆Control console of the old EMFC system (電磁濃縮法：旧制御盤)
custom made by Nichicon
The control console of the old EMFC system is also separated about 5 m from the anti-explosion box.
◆Primary coil of the EMFC method (電磁濃縮STDコイル)
home-made
The currently being used primary coil is called as "Cu-lined primary coil", which is provided with two-layer structures [1].
On the inner wall of the Fe coil, Cu coil of 2 mm thickness is hardly glued by stycast1266 (epoxy).
The liner made by the tough-pitch copper is placed inside the primary coil.
The typical dimension of liner is 119 mm of outer diameter, 50 mm of lingth, and 1.5 mm of thickness.
By modifying the dimension of the primary coil and the liner, we control the magnetic field curve for the many kinds of experiment.
[1] S. Takeyama, and E. Kojima, J. Phys. D: Appl. Phys. 44, 425003 (2011).
◆Seed field coil of the EMFC system (電磁濃縮種磁場コイル)
home-made
The seed field coil of the EMFC system (upper) is a Hermhortz coil of around 26 mH, in between which the primary coil is settled.
The typical bore diameter is 155 mm and the distance between the two split coils is 180 mm.
The magnetic field of 4 T within 50 ms can be generated by injecting the current from the seed condenser bank.
In experiments, a dummy coil of 1 mH (below) is connected in series for the accidental destruction of seed field coil.
◆Horizontal single-turn coil system (横型一巻きコイル装置)
custom made by Nichicon
The single-turn coil (STC) system can generate the magnetic fields of up to 300 T with the duration time of 6-8 microseconds by a fast-capacitor bank of 200 kJ.
We have two STC systems, one is a horizontal type (H-STC) and the other is a vertical type (V-STC).
Various kinds of laser spectroscopy experiments such as the cyclotron resonance and the Faraday rotation using the H-STC system are available.
Although the magnet coil destracts in every shot, the sample and the cryostat settled inside the magnet coil are not damaged by the magnetic field generation.
Therefore, we can perform the reproducible experiments using the same sample by using the STC system.
◆Vertical single-turn coil system (縦型一巻きコイル装置)
custom made by Nichicon
For very low-temperature experiments, a combination of the V-STC system with a liquid helium bath cryostat is very useful and the magnetization measurements at temperature as low as 2 K can be performed up to 120 T with high precision.
◆Condenser bank of single-turn coil system (一巻きコイル法電源)
custom made by Nichicon
The energy of 200 kJ fast condenser bank is used.
For V-STC system, the we can choose the unit number of the condenser bank system (100 kJ/ 200 kJ).
The air-gap switch is used for the discharge of each condenser.
◆Single-turn coil (一巻きコイル)
home-made
The magnet coil used in the single-turn coil system is made by wounded copper plate with thickness of 2 mm.
The several types of bore diameter of coil can be selected between 6-18 mm, in accordance with the type of experiments.
◆Control console for single-turn coil (一巻きコイル制御盤) custom made by Nichicon
Control console of the single-turn coil system is oprated for the charging/discharging of the condenser bank. The pneumatic pressure for the air-gap switch is automatically controlled in accordance with the charging voltage.
◆Non-destructive pulsed magnet (非破壊パルスマグネット)
home-made in Kindo lab.
The non-destructive pulsed magnet we used can generate the magnetic field up to 55 T, with the duration time of 36 ms.
The precise magneto-optical measurement is performed for a support of the experimental data measured under ultra-high magnetic fields above 100 T.
■ Vacuum/Low Temperature
◆Turbo pump (各種ターボポンプ)
custom made by APOLLOTEC Co. Ltd.
Turbo pump for (left) EMFC system, (middle) VSTC system, and (right) spectrophotometer. For the EMFC system, debris generated after the explosion of the magnet coil is effectively cut off from the pump line by the electromangetic valve. The pump line is designed to effectively reduce the organ pipe oscillation.
◆Miniature helium-flow cryostat for EMFC/HSTC (電磁濃縮/横型クライオスタット)
home-made
A handmade miniature liquid helium-flow type cryostat with an outer diameter of 6.0-6.5 mm is used for the EMFC and HSTC systems. The whole component was made of resin (Stycast1266 or bakelite). Bakelite cryostat (lower) can achieve the low temperature of 10 K, and Stycast1266 cryostat (upper) can achieve the lower temperature of 4.6 K, due to less leakage of vacuum at low temperatures [1].
[1] A. Miyata et al., J. Phys. Soc. Jpn. 81, 114701 (2012).
◆Helium bath cryostat for VSTC (縦型クライオスタット）
custom made by JECC TORISHA Co., Ltd.
The helium bath cryostat for VSTC [1] has liquid nitrogen layer, liquid helium layer and two vacuum layers.
Because the tail section of cryostat is inserted inside of the single-turn coil, the tail section is made of glass epoxy (fiber-reinforced plastic; FRP) thin tubes with 13.4 mm diameter.
The liquid helium container above the tail section has a capacity of 0.36 liter, and liquid helium is maintained for 5 hours at maximum.
By reducing the pressure of liquid helium container, low temperature of 2.3 K is maintained for 2 hours at maximum.
[1] S. Takeyama et al., J. Phys. Soc. Jpn. 81, 014702 (2012).
◆Liq. He transfer tube (液体ヘリウムトランスファーチューブ）
home-made
Flexible transfer tube of liquid helium is used for the use inside the anti-explosion box of the EMFC system.
Double pipe is made by annealed SUS pipes with 3mm and 5mm diameter. The inset is an enlarged view of the pointed end of double pipe.
◆Thermocouple (各種熱電対)
The thin (~70 um) thermocouple wire such as AuFe-Chromel and Chromel-Constantan is used for the temperature measurement, because of the limited space inside the magnet coil and the degradation of commercial resistive sensor by the elevtromagnetic noise and the shockwave.
High sampling frequency and high resolution of the A/D converter are nessesary for a single shot measurement under the ultra-high magnetic field.
For example, we use Lecroy, WaveRunner 604Zi (bandwidth of sampling rate: 10 GS/s, the vertical resolution: 8 bits) for the measurement using the signel-turn coil system.
RTD710A (SONY/Tektronix)
SBench M3i.4142 (Spectrum)
DC440 (Acqiris)
ADQ214 (SP Devices)
WaveRunner 604Zi (Recroy)
Vertical resolution
10 bit
14 bit
12 bit
14 bit
8 bit
Horizontal resolution
10(5) ns
4 ns
2.38 ns
2.5 ns
0.1 ns
Band resolution
100 MHz
200 MHz
100(300) MHz
850 MHz
400 MHz
Zin
1M W
50/1M W
50 W
50 W
50/1M W
Vmax
±50 V
±10 V
±10 V
±1.1 V
±40 V
port
2
8
2
2
4
◆High-speed digitizer (各種高速デジタイザ, A/Dボード)
For higher resolution of the A/D converter, the high-speed digitizer is used as well as the high-speed oscilloscope.
For example, RTD710A transient recorder (SONY/Tektronix) has 10 bit vertical resolution , and the time resolution is 5 ns.
M3i.4142 high-speed A/D board (SPECTRUM) has 14 bit vertical resolution, and the time resolution is 4 ns.
◆Ultra-high-speed framing and streak camera (コマ撮りカメラ)
DRS Hadland IMACON468
The shadowgraph of imploding liner of the EMFC method is taken for the investigation of the magnetic field generation mechanism. The eight frame photographs with 10 ns exposure time can be taken in a single shot. The right figure is the experimental setup and an example of liner's shadowgraph.
◆Ultra-high speed flush X-ray system (超高速フラッシュX線解析装置) Pulserad 43731A L-3 Communications
Flash X-ray system provides 150 kV X-rays with 70 ns exposure time. The X-ray radiography will be performed for the detailed investigation of the imploding liner's dynamics of the EMFC technique. At the final stage of implosion, huge flushright generates from the liner, which hinders the observation by the framing camera using the visible light. Therefore, we are developing the imaging system using the ultra-high speed flush X-ray system now (drawing is given by Dr. Ikeda).
◆Streak spectroscopy system for EMFC system (電磁濃縮用ストリーク分光装置) Acton ST-300is-6 + HAMAMATSU photonics C4187 + C4742-95
Time-resolved optical spectrum can be measured with the resolution of apploximately 10 ns. The incident light is diffracted by the spectroscope (ST-300is-6), and irradiates to the 2-dimensional imaging tube in the main frame (C4187) of streak system. Since photoelectrons are uniformly bended by time-varying high voltage during the exposure time, the intensity map as a function of the photon energy and the time can be obtained. Finally, the optical intensity map data are taken by the digital CCD camera (C4742-95).
◆Streak spectroscopy system for STC system (一巻きコイル用ストリーク分光装置)
HAMAMATSU photonics C5094 + C4187 + C4742-95
For the HSTC system, the same-type streak spectroscopy system for the EMFC system is installed. For the spectroscope, we used a different instrument (HAMAMATSU photonics C5094).
◆Light source (可視-近赤外光源)
Coherent, Inc. Mira900+Verdi 700-1000nm, CUBE 628nm,404nm, F6-690-100-10SMA 690 nm, Sapphire 532-100
, Innova 90C,
1550nm fiber laser,
B&W TEK Inc. 532 nm laser,
Edinburgh Instruments Ltd. PL3, PL5,
NEC GLG5800,
Neoark infrared He-Ne laser,
KIMMON HeCd laser,
Halogen lamp, Xe flush lamp XF-300E,
homemade H2O laser etc.
Many types of laser and flush lamp in the visible and near-infrared resion are used for the magneto-optical measurements.
◆Optical detector (光強度検出器)
New Focus model 1801, Acton SP2300 + Xenics Xeva-1052, Acton SpectraPro-300i etc.
For an optical detector, we used the high bandwidth photoreceiber (left) for detecting the ultrafast evolution of the light intensity. For the spectroscopy measurement, high-resolution CCD camera is used in combination with the spectroscope (right). The lower figure shows the whole optical instruments used under the ultra-high magnetic fields.
◆High frequency electrical conductivity measurement system (高周波電気伝導測定システム)
Agilent N5181A, Advantest R3131, etc.
Non-contact electrical conductivity measurement can be performed in the STC system. The RF signal generated by the sweeper (N5181A) transmits through the self-resonant coil settled in the STC, and detected by the digital oscilloscope after the super-heterodyne filtering (home-made). The resonant spectrum of the self-resonant coil changes by the sample's ellectrical conductivity placed on the self-resonant coil, which enables to measure the electrical conductivity of sample in the non-contact manner.
For the magneto-optical measurement using the non-destructive magnet, several types of the detector can be used. For obtaining the time-resolved absorption spectrum, ICCD (Intensified CCD) is used instead of the streak camera system. The incident light is diffracted by the spectroscope (MS257), and irradiates to the ICCD camera (DH734-18F-9B2). For the time-gated spectroscopy, cooled spectroscopy detector by liquid nitrogen is used in the near-infrared range (CCD) and the visible range (InGaAs).
◆Spectrophotometer (分光光度計)
JASCO V-570
Single monochromator of UV/VIS/NIR region (190-2500 nm). Deuterium lamp (190-350 nm) and Halogen lamp (330-2500 nm) are used as light sources. This spectrophotometer is used for the preliminary measurements at zero magnetic field. The right photograph shows the cryostat with optical windows, used in combination with the spectrophotometer.
◆PPMS (物理特性測定装置)
Quantum Design model 6000
Our Physical Properties Measurement System (PPMS) supports the magneto-resistivity and the heat capacity measurements up to 14 T. Ultra-low temperature up to 0.3 K can be achieved by using the helium-3 refrigerator. (This instrument is being managed by Kindo laboratory)
◆MPMS (磁気特性測定装置)
Quantum Design XL7L
Our Magnetic Properties Measurement System (MPMS) can perform the SQUID magnetometry up to 7 T. (This instrument is being managed by Kindo laboratory)
■ Others
◆Digital microscope (デジタル顕微鏡)
KEYENCE VHX-1000
By using this high-performance microscope, the pickup coil for the magnetic field probe is wound. The high-resolution photograph of sample can be also taken.
◆Winding machine of the seed field coil (種磁場巻線機)
custom-made by TRY Co.
The seed field magnet coil of the EMFC system is wound by this machine. The rotation speed of coil bobbin and the tensile strength of magnet wire can be adjustable. For the machining, the ventilate system is also equipped.
The thickness of sample can be evaluated with high precision (0.2 um) by the reflectometric interference spectroscopy between the sample surface and the reference surface in the sensor head.
◆Spin-coater (スピンコーター)
MIKASA opticoat MS-A100
Thin liquid film is uniformly deposited to flat substrates by a centrifugal force.
Low speed cutting is enabled by changing the rotation speed of the blade and the balance weight for the sample.
◆High presicion wire saw (ワイヤソー)
UNIPRESS WS-22
The wire saw enables cutting very thin slices (down to thickness of 10 um) with smooth cut surfaces (surface roughness does not exceed 1um), by a cutting technique which utilizes the precision guidance of the wire and uniform application of an abrasive slurry. The saw can be used for precision cutting of semiconductors, ferrites, metals, glasses as well as many other hard or brittle solids.
An extremely versatile optical fiber cleaver that can be used to produce both flat and angled cleaves on fibers ranging from 80 microns in diameter to 1.25 mm.
◆Muffle furnace (マッフル炉)
YAMATO FP41
Programmable furnace up to 1150℃ for the material systhesis and anneal.
◆Vacuum evaporation system (真空蒸着装置)
ULVAC VPC-260
The vaporized molucule in high vacuum is deposited on the substrate. We use it for making the electrode for the transport measurement.
Drying oven up to 250℃ is used for promoting the reaction of epoxy. The seed field magnet coil can be accomodate.
◆Anneal furnace, home-made (アニール炉)
The sample can be annealed up to 800℃.
◆Fume hood (ドラフトチャンバー)
Local ventilation device that is designed to limit exposure to hazardous or toxic fumes, vapors or dusts.
◆Machine shop (金属工作室)
We have two drilling machines, two lathes, and one milling machine for the machine work of the magnet and the instrument for measurements.
◆Student room (院生居室)
The student room can accommodate eight people at maxmimum. Desk and personal computer are supplied for separate each student. Air-conditioning system, refrigerator and dehumidifier are fully equipped. Security lock is done by the electronic key to the room.
