Kansai U., 2 Toyama U., 3 Osaka U., 4 Kyoto U.

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1 Keita KAMAKURA 1, Masaki ONISHI 1, Keiji MIYAMOTO 1, Hodaka OSAWA 1, Yuji HATANO 2 Tutomu MURATA 3, Kai MASUDA 4, Yasushi YAMAMOTO 1, Masami ONISHI 1 1 Kansai U., 2 Toyama U., 3 Osaka U., 4 Kyoto U.

2 About Tritium Purpose of the study IEC device 30(proto type) constructing and experimental results IEC device 25 constructing and experimental results Conclusion future plan

3 tritium s properties radioisotope (one proton and two neutrons.) half lifetime is 12.3 years radiates β rays and it means free path is 5mm in the air, and about 0.005mm in the water. Tritium gas decay 5mm in the air so it s safe to use for IEC device (Because of the law, tritium has to be recover as possible) hydrogen isotope Scale of D-T burning

4 To cause D-T reaction using IEC device To construct a new IEC device to use tritium safely Tritium gas will remain in the vacuum chamber. To recover 100% tritium gas is not possible. Test D-T burning at different institution which could experience D-T burning Osaka U. s facility OKTAVIAN is planned To use at OKTAVIAN, IEC device have to be small sized to move and set easily.

5 Power source Max rate: 80mA 125kV Max degree of vacuum rate : Using activated carbon to flow mixed DT gas. Outlet part is for open experiments. (D-T burning will be tested in hermetic situation)

6 feedthrough Power supply (Glassman NJ 08829) Mass flow meter a water bubbling container Vacuum chamber (diameter 30cm ) Includes dimeter 6cm cathode Completion

7 Experiment discharge voltage using hydrogen gas (discharge voltage using hydrogen gas and deuterium gas s characteristic is similer ) Objective : To increase the discharge voltage The higher the voltage is, the higher the neutron production From the graph, Kansai.U IEC device neutron production is expected to below To compare D-D burning and D-T burning in a max rate Higher presser range and Higher discharge voltage is required Goal: 60kV 0.8to1.4Pa

8 cathode Compatibility between anode and cathode To search the optimum size of cathode, Three types of cathode which was made by molybdenum was tested. To bring cathode to the center, the stainless part of the feedthrough has been resized. Stainless part of the feedthrough Adjustment part 12cm 8cm 11cm 30cm 30cm 30cm Cathode 6cm cathode14cm Schematic diagram of cathods(molibuden wire) Cathode 8cm

9 6cm 8cm The smaller the cathode is, the higher the discharge voltage. Higher pressure and higher discharge voltage is required. Main reason the voltage is low electric discharge is not stabile.(especially pass over 20kV) Gas pressure is too low 14cm

10 Cathode s middle ring glowed Condition. 14kV 50mA 0.61Pa Cleaning ionization vacuum gauge Sometimes the meter stops Ground connection is not enough? Mass flow meter Quadrupole mass spectrometer Runs down during high voltage experiment Clean this part(electrode)

11 As a result IEC 30(proto type) s discharge voltage is low. (Main reason : electric discharge is not stability) Use IEC device 25 Several cathode was tested but cathode size did not solve the problem. Instead of changing cathode, idea of changing anode was plan Size was refer to Kyoto U. s IEC device.

12 IEC25 is Instead of using IEC 30. Vacuum chmaber smaller than IEC 30 (300mm to 250mm) smaller and simplify new holes to attach windows to watch cathode. Vacuum chamber has been smaller. Pipes and components have to be changed. Vacuum chamaber Stainless Frame Pipes

13 70cm 175cm Closer look 150cm 60cm Power supply IEC 25 Power source Max rate: 80mA 125kV Max degree of vacuum rate : Water cooler jacket is more thin.

14 Experiment using hydrogen gas to search discharge characteristic. Results are compared with IEC device Comparison IEC 25 and IEC Voltage[V] IEC25 IEC Gas Pressure [Pa] Using same cathode(6 ring), placed at the center. discharge condition (20kV,10mA Pa) Gas Pressure rate have increased but voltage range is still low. During the experience, MFM have run down. For the safety, experiment have stop.

15 IEC 30 s discharge voltage is low Cathode size is not effective in this case. IEC 25 s gas pressure characteristic improve slightly. Still, discharge voltage characteristic is low. Consistently, ground connection is not enough. Copper Grounding plate is need to be equip.

16 Use IEC device 25 at Osaka U. OKATAVIAN. (Use the ground connection and try to experiment in max condition) Use deuterium gas for neutron production characteristic OKTAVIAN Find a method to search the remain tritium in the vacuum chamber (example: liquid scintillation, tritium monitor) Equip Water Bubbling System Test D-T Burning

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