{"created":"2023-06-20T13:21:17.025326+00:00","id":1422,"links":{},"metadata":{"_buckets":{"deposit":"248776da-a669-48d0-b984-874d2249de76"},"_deposit":{"created_by":21,"id":"1422","owners":[21],"pid":{"revision_id":0,"type":"depid","value":"1422"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00001422","sets":["2:428:14"]},"author_link":["0","0","0"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"亀島, 敬"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"カメシマ, タカシ"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2009-03-24"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"This dissertation reports the results of the research for electron beams acceleration with laser wakefield in capillary discharge plasma. The aim of this research is to increase energy gain of electron beams by solving a problem of laser wakefield acceleration, that is, shortness of acceleration length. Since excitation of the laser wakefield needs a laser pulse with a high intensity, the duration of the laser wakefield strictly depends on the length of laser focusing, which is fundamentally determined by diffraction of laser beams. The acceleration length is limited to be only a mm-scale owing to the diffraction effect. In order to overcome the diffraction limit, a discharge-plasma channel is proposed. The discharge-plasma channel generated in a capillary plays a role of an optical waveguide for propagating an intense laser pulse and prevents the laser pulse from defocusing over many Rayleigh lengths. This technique enables one to extend the acceleration length much longer to be a cm-scale that is required for accelerating electron beams up to the GeV-range energy. <br />　Ablative capillaries made from acrylic resin are investigated for the generation of discharge-plasma channel. Propagation of intense laser pulses in plasma depends on the radial profile of refraction index which is determined by a plasma density profile in the capillary. Therefore, the plasma density profile in the capillary-discharge-plasma channel was characterized by the plasma-spectroscopy measurement. The temporal evolution and the dependence on discharge current are acquired for the search of the optimum condition of laser optical guiding. In addition, plasma dynamics in the capillary are numerically simulated on base of magnet hydro-dynamics by using the parameters taken by the plasma-spectroscopy measurement. In the simulation, the plasma parameters such as density, temperature, and a current profile can be calculated from the measured discharge current and the material of the capillary wall. The results of the measurement and the simulation in good agreement verify that a formed density channel in the capillary is capable of optically guiding an intense laser pulse. <br />　Two experiments of laser wakefield acceleration were demonstrated with the ablative capillary and the ultra-intense lasers, the SILEX-I at the China Academy Engineering Physics (CAEP) and the J-KAREN at the Japan Atomic Energy Agency (JAEA). The laser system of the CAEP institute provides laser pulses with a maximum energy of 5.6 J and a pulse duration of 27 fs. Laser pulses up to energies of 4.4 J are optically guided in the capillary-discharge-plasma channel with a length of 4 cm. The laser spot size at the exit of the capillary is close to the initial injected one at the entrance of the capillary. When 3.8 J laser pulses are injected into the capillary-discharge-plasma channel, the GeV-class, high-quality beams are produced, showing an energy of 0.56 GeV, an energy spread of 0.21 % r.m.s., and a divergence of 0.58 mrad r.m.s. In the experiment at the JAEA institute, the stable conditions for the optical guiding and the electron productions are investigated. It is found that the optimum condition of the electron production is not always matched to that of the optical guiding. The designed capillary has a low plasma density at a timing of the optimum condition of the optical guiding. Therefore, the provision of electrons for the laser wakefield due to the background plasma is difficult to occur. In addition, erosion of ablative capillaries is inspected. It is observed that after more than 100 shots an enlargement of the capillary’s diameter is small enough to be negligible. However, warped irregularities and many blisters emerges around the inner wall of the capillary due to water absorption in the capillary wall and thermal expansion caused by discharge current. Such geometric distortion would make a plasma profile also warped, so that the path and the profile of a laser pulse would be strayed and deteriorated. <br />　The electron beams acceleration experiments with the investigated capillary verifies that the laser wakefield can accelerate electron beams up to GeV-class with high collimation through optical guiding in the capillary-discharge-plasma channel with a length of a cm-scale. These results shows a prospect of the arrival of ‘tabletop accelerators’ delivering high-quality GeV-range beams. With improvement of the capillary-discharge technique and separation of electron injection and acceleration, electron beams accelerated by the laser wakefield in the capillary-discharge-plasma channel is capable of achieving the strict beam parameters required by advanced accelerators, such as the x-ray free electron laser.","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第1230号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"高エネルギー加速器科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"12 加速器科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2008"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"KAMESHIMA, Takashi","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲1230_要旨.pdf","filesize":[{"value":"272.6 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨","url":"https://ir.soken.ac.jp/record/1422/files/甲1230_要旨.pdf"},"version_id":"c02f9a52-f829-4817-bb68-a7b7e9a328de"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"GeV-class High Quality Electron Beams Accelerated by Laser Wakefield in Capillary Discharge Plasma","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"GeV-class High Quality Electron Beams Accelerated by Laser Wakefield in Capillary Discharge Plasma"},{"subitem_title":"GeV-class High Quality Electron Beams Accelerated by Laser Wakefield in Capillary Discharge Plasma","subitem_title_language":"en"}]},"item_type_id":"1","owner":"21","path":["14"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-03-24"},"publish_date":"2010-03-24","publish_status":"0","recid":"1422","relation_version_is_last":true,"title":["GeV-class High Quality Electron Beams Accelerated by Laser Wakefield in Capillary Discharge Plasma"],"weko_creator_id":"21","weko_shared_id":-1},"updated":"2023-06-20T16:05:06.628622+00:00"}