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Sumi N, Kurashige T, Sueda Y, Ohta M, Kambara T, Sugiura T, Torii T. EGFR mutation and ALK fusion oncogene decrease stroke risk in patient with trousseau syndrome due to lung adenocarcinoma. J Neurol Sci 2017. [DOI: 10.1016/j.jns.2017.08.2827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Takahashi S, Nakamura M, Yonekura Y, Tanaka F, Tanno K, Ohsawa M, Itai K, Omama S, Ishibashi Y, Ogasawara K, Sakata K, Ohta M, Okayama A. P3454A comparison of the predictive ability of cardiovascular biomarkers for requiring long-term care service due to physical and cognitive impairments in an elderly general population. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx504.p3454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Tamaki K, Koshiyama M, Ohta M, Ohsawa M. P4610Prevalence rates of atrial fibrillation tentatively increased during and after the Great East Japan earthquake. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx504.p4610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Hasegawa H, Nakashima H, Matsui T, Ohta M. Helical Geometry Effect on Tritium Breeding in Heliotron Fusion Reactor Blanket. NUCL SCI ENG 2017. [DOI: 10.13182/nse84-a18642] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Koami H, Sakamoto Y, Yamada KC, Matsuda T, Nishi J, Nakayama K, Sakurai R, Ohta M, Imahase H, Yahata M, Umeka M, Miike T, Nagashima F, Iwamura T, Inoue S. What factor within the Japanese Association for Acute Medicine (JAAM) disseminated intravascular coagulation (DIC) criteria is most strongly correlated with trauma induced DIC? A retrospective study using thromboelastometry in a single center in Japan. Eur J Trauma Emerg Surg 2017; 43:431-438. [PMID: 28093623 PMCID: PMC5533846 DOI: 10.1007/s00068-016-0756-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/23/2016] [Indexed: 11/26/2022]
Abstract
Purpose The diagnostic criteria for disseminated intravascular coagulation (DIC) established by the Japanese Association for Acute Medicine (JAAM) is able to diagnose DIC accurately and promptly. The aim of this retrospective study is to evaluate the degree of association between each parameter of JAAM DIC criteria and the diagnosis of trauma induced DIC (T-DIC) utilizing thromboelastometry (ROTEM). Methods Trauma patients transported to our hospital with ROTEM performed in the emergency department between January 2013 and December 2015 were enrolled in this study. We evaluated (1) the characteristics of T-DIC, (2) the relationships between T-DIC and each parameter of the JAAM DIC criteria and (3) the diagnostic accuracies of each parameter for T-DIC by statistical measurement. Results All 72 patients (21 T-DIC and 51 control) were included in primary analysis. T-DIC was significantly related to younger age, more severe trauma scores, more cases of massive transfusions, and remarkable coagulation abnormality detected by standard coagulation tests. In the cases of T-DIC, ROTEM showed longer clotting time, lower acceleration, lower clot firmness, and inhibited fibrinolysis in EXTEM/INTEM. Within the JAAM DIC score, PT-INR ≥1.2 was the most accurate factor for T-DIC diagnosis; sensitivity 60.0%, specificity 100.0%, and accuracy 88.7%. PT-INR ≥1.2 was statistically correlated with the JAAM DIC score (p < 0.001, r = 0.709). The univariate analysis based on 1.2 of PT-INR indicated statistical differences in most categories of ROTEM, which is similar to analysis performed for the presence and absence of T-DIC. Conclusions Among JAAM DIC criteria, the PT-INR ≥1.2 was the most accurate factor for both the diagnosis of T-DIC and the evaluation of its severity.
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Kaneko Y, Kondo H, Ohta M, Takeuchi T. FRI0104 Long-Term Followup of Biologic Agents in Patients with Rheumatoid Arthritis. Ann Rheum Dis 2016. [DOI: 10.1136/annrheumdis-2016-eular.3339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Takai I, Matsubara H, Soga M, Ohta M, Ogawa M, Yamashita T. Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems. SENSORS 2016; 16:459. [PMID: 27043569 PMCID: PMC4850973 DOI: 10.3390/s16040459] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/25/2016] [Accepted: 03/25/2016] [Indexed: 12/04/2022]
Abstract
A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25–132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50–180 cm.
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Wakuno A, Aoki M, Kushiro A, Mae N, Kodaira K, Maeda T, Yamazaki Y, Ohta M. Comparison of alfaxalone, ketamine and thiopental for anaesthetic induction and recovery in Thoroughbred horses premedicated with medetomidine and midazolam. Equine Vet J 2016; 49:94-98. [PMID: 26850885 DOI: 10.1111/evj.12548] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 11/25/2015] [Indexed: 11/28/2022]
Abstract
REASONS FOR PERFORMING STUDY There is limited information on clinical use of the new injectable anaesthetic agent alfaxalone in Thoroughbred horses. OBJECTIVES To compare anaesthetic induction and recovery characteristics and cardiopulmonary responses between alfaxalone, ketamine and thiopental in Thoroughbred horses premedicated with medetomidine and midazolam. STUDY DESIGN Randomised blinded experimental cross-over study. METHODS Six Thoroughbred horses were anaesthetised 3 times with alfaxalone 1 mg/kg bwt, ketamine 2.5 mg/kg bwt or thiopental 4 mg/kg bwt after premedication with medetomidine 6 μg/kg bwt and midazolam 20 μg/kg bwt. Qualities of anaesthetic induction and recovery were scored on a scale of 1 (poor) to 5 (excellent). Induction time and recovery time were recorded. Cardiopulmonary values (heart rate, respiratory rate, arterial blood pressures, and arterial blood gases) were recorded throughout anaesthesia. Data were analysed with nonparametric methods. RESULTS The anaesthetic induction (P = 0.2) and recovery (P = 0.1) quality scores (median, range) were not different amongst protocols and were 4.0, 3-5; 5.0, 4-5; 4.5, 3-5; and 4.5, 3-5; 3.5, 2-5; 4.0, 2-5 for alfaxalone, ketamine and thiopental, respectively. Induction time for ketamine (67, 53-89 s) was significantly longer than that for alfaxalone (49, 40-51 s, P = 0.01) and thiopental (48, 43-50 s, P = 0.01). Time to standing for alfaxalone (44, 40-63 min, P = 0.01) and thiopental (39, 30-58 min, P = 0.01) was significantly longer than that for ketamine (25, 18-26 min). Cardiovascular values were maintained within the clinically acceptable level throughout anaesthesia. Respiratory rate significantly decreased during anaesthesia for all 3 drugs; however, spontaneous breathing did not disappear, and PaCO2 values were maintained at approximately 50 mmHg. CONCLUSIONS All 3 drugs showed similar effects in relation to anaesthetic induction and recovery qualities and cardiopulmonary responses. However, alfaxalone and thiopental prolonged recovery time compared with ketamine.
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Anzai H, Yoshida Y, Sugiyama S, Endo H, Matsumoto Y, Ohta M. Porosity dependency of an optimized stent design for an intracranial aneurysm. Technol Health Care 2015; 23:547-56. [PMID: 26410116 DOI: 10.3233/thc-151007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Optimal design of stents for a cerebral aneurysm is desired for efficient flow reduction in the aneurysm. OBJECTIVE In this study, we aimed to optimize stent design at several porosities, estimate the influence of stent design on aneurysm flow, and evaluate the ability of stents to reduce flow. METHODS Stent models were constructed as sets of squares or rectangles in the necks of a two-dimensional (2D) and realistic aneurysm. Then, automated optimization was performed using a combination of simulated annealing and lattice Boltzmann flow simulation. RESULTS By simulated annealing, stents were gradually modified to reduce the average velocity in an aneurysm. As a result of optimization, stents of all porosities demonstrated an inhomogeneous distribution with dense struts in the inflow area. Flow reduction was increased compared with the initial stent. Under the condition of high porosity, flow reduction by the stent drastically increased as porosity decreased. Under low porosity, the increase of velocity reduction was moderate even as porosity decreased. CONCLUSIONS Optimization can enhance flow reduction by stents. However, the increase in reduction associated with decreasing porosity is moderate under lower-porosity conditions. This threshold may help in the choice of stent porosity for each specific aneurysm.
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Kaneko Y, Kondo H, Ohta M, Takeuchi T. SAT0095 Identifying Factors Associated with Discordance Between Erythrocyte Sedimentation Rate and C-Reactive Protein in Patients with Rheumatoid Arthritis. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-eular.4352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kusumoto T, Ohta M, Kimura Y, Tsutsumi N, Sugiyama M, Kusumoto E, Sakaguchi Y, Ikejiri K, Saeki H, Oki E, Maehara Y. Validation of postoperative adjuvant chemotherapy for elderly patients with stage II/III gastric cancer. J Clin Oncol 2015. [DOI: 10.1200/jco.2015.33.15_suppl.e15036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Kimura Y, Kusumoto T, Kusumoto E, Sugiyama M, Ohta M, Tsutsumi N, Sakaguchi Y, Ikejiri K. The comparison of the usefulness of nab-paclitaxel and paclitaxel for advanced or recurrent gastric cancer. J Clin Oncol 2015. [DOI: 10.1200/jco.2015.33.3_suppl.217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
217 Background: For patients who do not respond to S-1-based treatment in Japan, weekly paclitaxel (PTX) therapy is more frequently used as second-line chemotherapy. On the other hand, the agent could not be used for alcohol hypersensitivity in some cases. Nab-Paclitaxel (N-PTX), which is the protein-bound paclitaxel, has recently been introduced in Japan. The purpose of this study was to retrospectively determine the more preferable agent, N-PTX or PTX, following the S-1-containing chemotherapy in patients with advanced or recurrent gastric cancer (ARGC). Methods: We conducted a retrospective review of the data for 40 patients with ARGC, who received either N-PTX monotherapy for 5 patients or PTX monotherapy for 35 patients. N-PTX was used as the second-line for all patients in this group. On the other hand, in the PTX group, 4, 28 and 3 patients received PTX monotherapy as the 1st-, 2nd- and 3rd-line, respectively. N-PTX was administered intravenously at a dose of 260 mg/m2 repeated triweekly. PTX was administered intravenously at a dose of 80 mg/m2repeated weekly (on days 1, 8 and 15) every four weeks. The objective response rate (ORR), adverse events, progression-free survival (PFS) were compared between the two groups. Results: For tumor response, in the N-PTX group, CR/PR/SD/PD were 0/3/1/1, respectively for an ORR of 60% and a DCR of 80%; in the PTX group, CR/PR/SD/PD were 0/3/15/13, respectively for an ORR of 10% and a DCR of 58%. The ORR of the N-PTX group was higher, which might result from the higher dose intensity in the group, compared with the PTX group. For the adverse toxicity, in the both group, events of grade ≥ 3 were not observed. Serious neurotoxicity (≥grade 3), as commonly described for treatment with paclitaxel, was not observed in this study. The survival data showed that the PFS was 253 days in the N-PTX group, compared with 176 days in the PTX group, which were not significantly different. Conclusions: We suggest the application of N-PTX in place of PTX after S-1 containing chemotherapy for ARGC, only from the perspective of the tumor response. Further data accumulation is required for overall survival.
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Goto M, Makihara H, Ohta M, Maseki S, Hasegawa Y, Nakanishi H, Kurita K. Biological significance and regulation of podoplanin expression in oral squamous cell carcinomas. J Oral Maxillofac Surg 2014. [DOI: 10.1016/j.joms.2014.06.328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Moriyama M, Furukawa S, Kawano S, Goto Y, Kiyoshima T, Tanaka A, Maehara T, Hayashida JN, Ohta M, Nakamura S. The diagnostic utility of biopsies from the submandibular and labial salivary glands in IgG4-related dacryoadenitis and sialoadenitis, so-called Mikulicz's disease. Int J Oral Maxillofac Surg 2014; 43:1276-81. [PMID: 25062551 DOI: 10.1016/j.ijom.2014.06.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 06/26/2014] [Accepted: 06/30/2014] [Indexed: 12/24/2022]
Abstract
IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS) is characterized by serum IgG4 elevation and the infiltration of IgG4-positive plasma cells in glandular tissues. For definitive diagnosis of IgG4-DS, biopsies of local lesions are recommended to exclude Sjögren's syndrome (SS), malignant tumours, and similar disorders. In this study, we examined the diagnostic utility of submandibular gland (SMG) and labial salivary gland (LSG) biopsies in IgG4-DS. Fourteen patients presenting with swelling of the SMG (eight females and six males) underwent both SMG and LSG biopsies. The sensitivity, specificity, and accuracy of SMG biopsies were all 100.0%. In contrast, those of LSG biopsies were 69.2%, 100.0%, and 71.4%, respectively. Thirty-three out of 61 LSG biopsies (54.1%) from all 14 patients were positive for the diagnostic criteria of IgG4-DS (IgG4-positive/IgG-positive plasma cells >0.4). None of the patients experienced complications such as facial nerve palsy, sialocele, or hyposalivation. The IgG4/IgG ratio showed no significant correlation between the LSG and SMG. The final diagnosis was IgG4-DS in 13 patients and marginal zone B-cell lymphoma (MZL) in one. These results suggest that incisional biopsy of the SMG is useful and appropriate for the definitive diagnosis of IgG4-DS, while diagnosis by LSG biopsy alone requires more caution.
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Furukawa S, Moriyama M, Kawano S, Tanaka A, Maehara T, Hayashida JN, Goto Y, Kiyoshima T, Shiratsuchi H, Ohyama Y, Ohta M, Imabayashi Y, Nakamura S. Clinical relevance of Küttner tumour and IgG4-related dacryoadenitis and sialoadenitis. Oral Dis 2014; 21:257-62. [PMID: 24844187 PMCID: PMC4359042 DOI: 10.1111/odi.12259] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/05/2014] [Accepted: 05/14/2014] [Indexed: 12/24/2022]
Abstract
Objectives Küttner tumour (KT), so-called chronic sclerosing sialoadenitis, is characterised by concomitant swelling of the submandibular glands secondary to strong lymphocytic infiltration and fibrosis independent of sialolith formation. However, recent studies have indicated that some patients with KT develop high serum levels of IgG4 and infiltration of IgG4-positive plasma cells, namely IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS), so-called Mikulicz's disease. The aim of this study was to clarify the clinical and pathological associations between KT and IgG4-DS. Materials and Methods Fifty-four patients pathologically diagnosed with KT or chronic sialoadenitis were divided into two groups according to the presence or absence of sialolith (KT-S (+) or KT-S (−), respectively). Results There were no significant differences in the clinical findings, including the mean age, sex and disease duration, between the two groups. All patients in the KT-S (+) group showed unilateral swelling without infiltration of IgG4-positive plasma cells or a history of other IgG4-related diseases (IgG4-RD), while those in the KT-S (−) group showed bilateral swelling (37.5%), strong infiltration of IgG4-positive plasma cells (87.5%) and a history of other IgG4-RD (12.5%). Conclusions These results suggest an association between the pathogeneses of KT-S (−) and IgG4-DS, but not KT-S (+).
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Ohta M, Nakamura K, Kubo T, Suzuki T. Detoxification Effect of Iron-encaging Zeolite-processed Water in Tributyltin-intoxicated Euglena gracilis Z. Biosci Biotechnol Biochem 2014; 65:14-21. [PMID: 11272817 DOI: 10.1271/bbb.65.14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In our previous paper, we reported the restoration promoting effects of mineral-encaging zeolite-processed water, especially of a Fe-encaging one, on tributyltin chloride (TBTCl)-intoxicated Euglena gracilis. This present study extends the investigation on the behavior of TBTCl and a xenobiotic enzyme, cytochrome P-450, in Euglena cells incubated with or without Fe-encaging zeolite-processed water (FeZW). Subcellular fractionation of TBTCl-intoxicated Euglena cells, atomic absorption spectrophotometry, and GC analyses showed that TBTCl was rapidly incorporated into the cells to halt cell motility. GC-MS showed that FeZW promoted conversion of TBTCl to dibutyltin (DBT) as the major metabolite in the microsomal fraction of the cells. An in vitro incubation system with heat-treated microsomes did not convert TBTCl to DBT. The contribution of cytochrome P-450 in the microsomal fraction was suggested by an immunochemical method. The results suggest that the improvement of detoxification by FeZW in the TBT-intoxicated Euglena cells should be due to activation of biotransformation system of the Euglena cells by FeZW.
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Kusumoto T, Kimura Y, Tsutsumi N, Ohta M, Sugiyama M, Kusumoto E, Sakaguchi Y, Ikejiri K, Saeki H, Oki E, Maehara Y. Trastuzumab plus chemotherapy based on the accurate HER2-positivity testing for patients with advanced gastric cancer. J Clin Oncol 2014. [DOI: 10.1200/jco.2014.32.15_suppl.e15075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Ohyama K, Moriyama M, Hayashida JN, Tanaka A, Maehara T, Ieda S, Furukawa S, Ohta M, Imabayashi Y, Nakamura S. Saliva as a potential tool for diagnosis of dry mouth including Sjögren's syndrome. Oral Dis 2014; 21:224-31. [DOI: 10.1111/odi.12252] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/10/2014] [Accepted: 04/15/2014] [Indexed: 01/29/2023]
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Yahata M, Sakamoto Y, Inoue S, Iwamura T, Fujita R, Koami H, Miike T, Imahase H, Narumi S, Goto A, Ohta M. More effective use of polymyxin-B hemoperfusion for nonoperation cases. Crit Care 2014. [PMCID: PMC4273848 DOI: 10.1186/cc14035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Yamamoto T, Shibata T, Ohta M, Yasumoto M, Nishida K, Hatayama A, Mattei S, Lettry J, Sawada K, Fantz U. Modeling of neutrals in the Linac4 H(-) ion source plasma: hydrogen atom production density profile and Hα intensity by collisional radiative model. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:02B118. [PMID: 24593558 DOI: 10.1063/1.4833016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To control the H(0) atom production profile in the H(-) ion sources is one of the important issues for the efficient and uniform surface H(-) production. The purpose of this study is to construct a collisional radiative (CR) model to calculate the effective production rate of H(0) atoms from H2 molecules in the model geometry of the radio-frequency (RF) H(-) ion source for Linac4 accelerator. In order to validate the CR model by comparison with the experimental results from the optical emission spectroscopy, it is also necessary for the model to calculate Balmer photon emission rate in the source. As a basic test of the model, the time evolutions of H(0) production and the Balmer Hα photon emission rate are calculated for given electron energy distribution functions in the Linac4 RF H(-) ion source. Reasonable test results are obtained and basis for the detailed comparisons with experimental results have been established.
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Ohta M, Mattei S, Yasumoto M, Hatayama A, Lettry J. Numerical study of the inductive plasma coupling to ramp up the plasma density for the Linac4 H(-) ion source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:02B113. [PMID: 24593553 DOI: 10.1063/1.4833920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the Linac4 H(-) ion source, the plasma is generated by an RF antenna operated at 2 MHz. In order to investigate the conditions necessary for ramping up the plasma density of the Linac4 H(-) ion source in the low plasma density, a numerical study has been performed for a wide range of parameter space of RF coil current and initial pressure from H2 gas injection. We have employed an Electromagnetic Particle in Cell model, in which the collision processes have been calculated by a Monte Carlo method. The results have shown that the range of initial gas pressure from 2 to 3 Pa is suitable for ramping up plasma density via inductive coupling.
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Nishida K, Mochizuki S, Ohta M, Yasumoto M, Lettry J, Mattei S, Hatayama A. Equivalent circuit of radio frequency-plasma with the transformer model. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:02B117. [PMID: 24593557 DOI: 10.1063/1.4832060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
LINAC4 H(-) source is radio frequency (RF) driven type source. In the RF system, it is required to match the load impedance, which includes H(-) source, to that of final amplifier. We model RF plasma inside the H(-) source as circuit elements using transformer model so that characteristics of the load impedance become calculable. It has been shown that the modeling based on the transformer model works well to predict the resistance and inductance of the plasma.
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Lettry J, Aguglia D, Andersson P, Bertolo S, Butterworth A, Coutron Y, Dallocchio A, Chaudet E, Gil-Flores J, Guida R, Hansen J, Hatayama A, Koszar I, Mahner E, Mastrostefano C, Mathot S, Mattei S, Midttun Ø, Moyret P, Nisbet D, Nishida K, O'Neil M, Ohta M, Paoluzzi M, Pasquino C, Pereira H, Rochez J, Sanchez Alvarez J, Sanchez Arias J, Scrivens R, Shibata T, Steyaert D, Thaus N, Yamamoto T. Status and operation of the Linac4 ion source prototypes. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:02B122. [PMID: 24593562 DOI: 10.1063/1.4848975] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
CERN's Linac4 45 kV H(-) ion sources prototypes are installed at a dedicated ion source test stand and in the Linac4 tunnel. The operation of the pulsed hydrogen injection, RF sustained plasma, and pulsed high voltages are described. The first experimental results of two prototypes relying on 2 MHz RF-plasma heating are presented. The plasma is ignited via capacitive coupling, and sustained by inductive coupling. The light emitted from the plasma is collected by viewports pointing to the plasma chamber wall in the middle of the RF solenoid and to the plasma chamber axis. Preliminary measurements of optical emission spectroscopy and photometry of the plasma have been performed. The design of a cesiated ion source is presented. The volume source has produced a 45 keV H(-) beam of 16-22 mA which has successfully been used for the commissioning of the Low Energy Beam Transport (LEBT), Radio Frequency Quadrupole (RFQ) accelerator, and chopper of Linac4.
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Mattei S, Ohta M, Yasumoto M, Hatayama A, Lettry J, Grudiev A. Plasma ignition and steady state simulations of the Linac4 H(-) ion source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:02B115. [PMID: 24593555 DOI: 10.1063/1.4833919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The RF heating of the plasma in the Linac4 H(-) ion source has been simulated using a particle-in-cell Monte Carlo collision method. This model is applied to investigate the plasma formation starting from an initial low electron density of 10(12) m(-3) and its stabilization at 10(18) m(-3). The plasma discharge at low electron density is driven by the capacitive coupling with the electric field generated by the antenna, and as the electron density increases the capacitive electric field is shielded by the plasma and induction drives the plasma heating process. Plasma properties such as e(-)/ion densities and energies, sheath formation, and shielding effect are presented and provide insight to the plasma properties of the hydrogen plasma.
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Hatayama A, Shibata T, Nishioka S, Ohta M, Yasumoto M, Nishida K, Yamamoto T, Miyamoto K, Fukano A, Mizuno T. Kinetic modeling of particle dynamics in H(-) negative ion sources (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:02A510. [PMID: 24593433 DOI: 10.1063/1.4852300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Progress in the kinetic modeling of particle dynamics in H(-) negative ion source plasmas and their comparisons with experiments are reviewed, and discussed with some new results. Main focus is placed on the following two topics, which are important for the research and development of large negative ion sources and high power H(-) ion beams: (i) Effects of non-equilibrium features of EEDF (electron energy distribution function) on H(-) production, and (ii) extraction physics of H(-) ions and beam optics.
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