200839162 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種冷凍機。 【先前技術】 為測量於4K附近之極低温環境下的試料物理性質、或測 里已使用利用極低溫環境之感測器等的各種物理量等，而 利用GM冷;東機。此冷;東機係藉由反複進行氦氣等冷媒氣 體之壓縮及膨服（冷;東循環），而將被冷卻物冷卻至極低溫 者。但因起因於上述冷凍循環之熱流的脈動，而於被冷卻 物之載置面產生溫度振幅。為穩定地冷卻被冷卻物，希望 降低此溫度振幅。 於專利文獻1中揭示了一種極低溫冷凍機，其包含設於 安裝被冷卻物之冷卻部、於内部儲存氦氣或氦氣及液體氦 之蓄冷機構’與連接壓縮氦氣之供給機構及前述蓄冷機構 的氦氣導入排出機構。 於專利文獻2中揭示了一種極低溫溫度調節器，其具備 有於常溫下導入必要量之氦氣的氦氣導入管、使氦氣液化 之冷凝器室、及儲存被液化之液體氦的液體氦室。 [專利文獻1]曰本專利第2773793號公報 [專利文獻2]日本專利特開2〇〇4_76955號公報 【發明内容】 [發明所欲解決之問題] 然而，因專利文獻1之極低溫冷凍機的前述溫度振幅係 3〇 mK左右，故希望溫度振幅進一步降低。 127199.doc 200839162 另一方面，因專利文獻2之極低溫溫度調節器結構複 雜，此外來自冷卻物之傳熱流路較長且為非軸對稱，故存 在冷卻不均勻且不穩定之虞。 本發明係為解決上述問題而完成者，其目的在於提供— 種可降低被冷卻物之載置面上的溫度振幅，此外可對被冷 卻物進行均勻、穩定之冷卻的冷凍機。 7 [解決問題之技術手段] 為解決上述問題，本發明採用以下之手段。即，本發明 之冷来機包括：冷卻台，其係冷卻被冷卻物；氦冷凝部， 其係載置前述被冷卻物；儲存器，其係與前述氦冷凝部連 通，填充有氦氣；及傳熱緩衝材料，其係配置於前述冷卻 台與前述氦冷凝部之間，包含熱傳導率比前述氦冷凝部低 之材料。 若藉由此構成，則起因於冷凍機之冷凍循環的熱流脈動 由氦冷凝部之氦的蒸發及冷凝（相轉移）所吸收。此時，傳 熱緩衝材料作為熱流之節流機構起作用，故可抑制冷卻台 之溫度振幅的傳遞。其結果，可降低被冷卻物之載置面上 的溫度振幅。此外，因冷卻台、傳熱緩衝材料、氦冷凝部 及被冷卻物連續配置為同轴狀，故被冷卻物可均勻、穩定 地冷卻。 前述氦冷凝部可包含4K附近之溫度中熱傳導率為2〇〇 W/(m · K)以上之材料。 若藉由此構成，則藉由於氦冷凝部内冷凝之液體氦，可 效率佳地冷卻被冷卻物。 127199.doc 200839162 前述傳熱緩衝材料可包含4K附近之溫度中熱傳導率不足 100 W/(m · Κ)之材料。 右藉由此構成，則可確實地防止冷卻台之溫度振幅的傳 遞。 、 前述氦冷凝部之容積可為10 CC以上100 CC以下。 若藉由此構成，則可確保被冷卻物之冷卻所必需之液體 氦的儲存容積，並可將氦冷凝部小型化。 别述儲存器之容積可為前述氦冷凝部之容積的5倍以上 100倍以下。 若藉由此構成，則可確保被冷卻物之冷卻所 的儲存容積，並可將儲存器小型化。 真充於別述儲存器之前述氮氣的壓力，於室溫 〇.1馗匕以上1.()“1^以下。 為 ★ * — 構成則即使冷象機停止，氦冷凝部之液體氦 蒸發丄亦可防止儲存器及氦冷凝部形成高壓力。 / 於則述氦冷凝部之内面可立式設置散熱片。 料，於前述氦冷凝部之内面可安裝多孔結構體。 若藉由此等構成，目,丨m &、人 成則因氪冷减部之内面與液體氦的接觸 :積變大，故可效果佳地冷卻載置於氣冷凝部之被冷卻 冷凝部之接 於前述傳熱緩衝材料與前述冷卻台或前述氦 觸面可形成凹凸。 若藉由此構成 之接觸面積變小 則因傳熱緩衝材料與冷卻台或氦冷凝部 故可抑制冷卻台之溫度振幅的傳遞。其 127199.doc 200839162 結果，可降低被冷卻物之載置面上的溫度振幅。 可進而包括：溫度感測器及加熱器，其係安裝於前述氦 冷凝部，及控制部，其係基於前述溫度感測器之測量結果 驅動前述加熱器。 若藉由此構成，則於氦冷凝部之溫度低於預定值之情 形，可驅動加熱器使氦冷凝部之溫度回歸至預定值。因 此，可降低被冷卻物之載置面上的溫度振幅。 [發明之效果] 若藉由本發明，則藉由設置傳熱緩衝材料，可防止冷卻 台之溫度振幅的傳遞，其結果，可降低被冷卻物之載置面 上的溫度振幅。此外，因冷卻台、傳熱緩衝材料、氦冷凝 部及被冷卻物連續配置為同軸狀，故被冷卻物可均勻、穩 定地冷卻。 【實施方式】 以下，就本發明之實施形態參照圖式進行說明。 [第1實施形態] 圖1係本發明第1實施形態相關之冷凍機的概略構成圖。 本實施形態相關之冷凍機1係具備冷卻被冷卻物4〇之第2冷 卻台14 ;載置被冷卻物40之氦冷凝部20 ;與氦冷凝部20連 通’填充有氦氣50之儲存器30 ;及配置於第2冷卻台14與 氦冷凝部20之間，由熱傳導率比氦冷凝部2〇低之材料構成 的傳熱緩衝材料16者。 冷凍機1主要具備有壓縮機4、本體部2及冷卻部1 5。壓 縮機4係壓縮由低壓配管8供給之低壓氦氣使之成為高壓氦 127199.doc 200839162 氣，並向高壓配管6供給者。本體部2係藉由馬達等之動力 連績切換咼壓配管6及低壓配管8與下述之冷卻部1 5内的氣 氣流路之連接者。 與本體部2連接，而設有冷卻部丨5。冷卻部丨5係配置於 保持於真空環境之真空槽10的内部，並藉由流經内部之氦 就的知服而使寒冷產生者。於冷卻部，依序設有第 卻部11、第1冷卻台12、第2冷卻部13及第2冷卻台14。第1 冷卻部11及第2冷卻部13形成為圓柱狀，第1冷卻台12及第 2冷卻台14形成為圓盤狀’且配置為同軸狀。於冷卻部1 $ 之内部，形成有氦氣流路（未圖示）。向此氦氣流路供給之 局壓氦氣於第2冷卻台14吸熱膨脹，並變化為低壓氦氣。 於第2冷卻台14之下面，與後述之氦冷凝部2〇之間設有 傳熱緩衝材料16。傳熱緩衝材料16例如形成為直徑數十 mm左右、厚度2 mm左右之板狀。傳熱緩衝材料16於4尺附 近之溫度中的熱傳導率比後述之氦冷凝部20低，且由不銹 鋼材料等構成。特別是若以於4K附近溫度中之熱傳導率不 足100 W/(m · K)的材料構成傳熱缓衝材料16，則可抑制第 2冷卻台14之溫度振幅傳遞至氦冷凝部2〇。 再者’為提高熱接觸性而於傳熱緩衝材料16之兩面貼附 、，〇泊4，連結弟2冷卻台14、傳熱緩衝材料16及氦冷凝部 20 〇 於傳熱緩衝材料16之下面，設有載置被冷卻物4〇之氦冷 凝部20。氦冷凝部2〇於4尺附近之溫度中的熱傳導率比前述 之傳熱緩衝材料16高，由銅、銀、鋁等材料構成。本實施 127199.doc 200839162 形態中，藉由無氧銅形成氦冷凝部20。特別是若以於4K附 近溫度中之熱傳導率為200 W/(m · Κ)以上的材料構成氦冷 凝部20，則可藉由於氦冷凝部20内冷凝之液體氦，效率佳 地冷卻被冷卻物4 0。 氦冷凝部2 0形成為兩端密閉之圓筒狀，於内部儲存液體 氦。若以此氦冷凝部20之容積為10 cc以上1〇〇 cc以下，則 可確保冷卻被冷卻物40所必需之液體氦的儲存容積，並可 將氦冷凝部20小型化。本實施狀態中，氦冷凝部2〇之容積 設定為40 cc。 於氦冷凝部20之下面，配置有工作台4 1。此工作台41之 下面成為被冷卻物40載置場所的冷卻位置。工作台4丨由具 有與氦冷凝部20相同之物理性質的材料構成。本實施形態 中’於氦冷凝部20與工作台41之間以及工作台41與被冷卻 物40之間貼附銦箔等，連結氦冷凝部2〇與工作台41。再者 亦可不設置工作台4 1，而將被冷卻物40熱接觸佳地貼附至 氦冷凝部20。 上述之冷卻部1 5的第2冷卻台14、傳熱緩衝材料丨6、氦 冷凝部20及被冷卻物40構成來自被冷卻物之傳熱流路。本 實施形態中，藉由將此等連續配置為同軸狀，可縮短傳熱 流路之距離。藉此，可降低冷卻損失，可於短時間内將被 冷卻物40效率佳地冷卻至目的溫度。此外，可將傳熱流路 設為軸對稱形狀，可對被冷卻物4〇之整體均勻且穩定地冷 卻。 自氦冷凝部20延長設置細管32，並始終與配置於真空_ 127199.doc 11 200839162 1 〇之外部的儲存;杳& 連接。儲存器30之容積宜為氦冷凝部 20之谷積的5^立以μ α上l〇(H口以下。本實施狀態中，儲存哭 之容積設定為3250 cc。蕤μμ叮☆ 精此’可確保被冷卻物4〇之冷卻所 必需之氦氣的儲存容積，並可將儲存器30小型化。 —於儲存器30之内部填充有氦氣。此氦氣之麼力於室溫下 且為0.1 MPa以上1.0 MPa以下。本實施形態中，於儲存器 3〇中填充室溫下屋力為〇 4 Mpa的氦氣5〇。藉此，即使冷 束機1停止’氦冷凝部20之液體氦52蒸發，儲存器3〇亦不 會形成高壓力。再者，於細管32之中間部，形成有用以與 第1冷卻台12進行熱交換之熱固定器34。 其次，就本實施形態相關之冷凍機1的作用進行說明。 如上所述，由壓縮機4向冷卻部15供給之高壓氦氣於第2冷 卻台14吸熱膨脹，變化為低壓氦氣。本體部2連續地切換 高壓配管6及低壓配管8與冷卻部15之氦氣流路的連接。藉 此，反複進行氦氣之壓縮及膨脹（冷凍循環），從而第2冷卻 台14之溫度變成極低温。 於第2冷卻台14之下方，設有氦冷凝部2〇。若藉由第2冷 卻台14冷卻氦冷凝部20，則氦冷凝部20之内部的氦氣冷凝 並液化’生成液體氦5 2。本實施形態中，以對於氦冷凝部 2〇之容積比為30%以下（例如20%左右）之方式生成液體 氦0 且說因起因於上述之冷凍循環的熱流脈動，而於第2冷 卻台14產生溫度振幅。然而’本實施形態中，起因於冷〉東 循環之熱流脈動由氦之蒸發及冷凝（相轉移）所吸收。因 -12- 127199.doc 200839162 此’不會於氦冷凝部20產生與第2冷卻台14同等之溫度振 幅，氦冷凝部20之溫度振幅變小。 而且本實施形態中，於第2冷卻台14與氦冷凝部2〇之 間，設有由熱傳導率比氦冷凝部20低之材料形成的傳熱緩 衝材料16。因該傳熱緩衝材料16作為熱流之節流機構發揮 作用，故可抑制第2冷卻台14之溫度振幅傳導至氦冷凝部 20。因此可降低被冷卻物之載置面上的溫度振幅。 圖2係顯示第2冷卻台之溫度與溫度振幅之關係的圖表。 此處，對3種裝置構成測定了溫度振幅。具體言之，測定 了（1)與本實施形態同樣，設置了第2冷卻台14、傳熱緩衝 材料16及氦冷凝部20之情形的氦冷凝部20之溫度振幅（菱 形圖案）、（2)不設置傳熱缓衝材料16，設置了第2冷卻台14 及乱冷减部2 0之情形的氦冷凝部2 0之溫度振幅（三角形圖 案）、及（3)不設置傳熱緩衝材料16及氦冷凝部2〇之情形的 第2冷卻台14之溫度振幅（圓形圖案）。橫轴取作為被冷卻物 載置場所之冷卻位置（溫度振幅之測定位置）的溫度。再 者，將儲存器30之容積設定為3250 cc、對儲存器3〇之氦氣 填充壓力設定為0.4 Mp a、氦冷凝部2 0之内部的液體氦容 積比設定為20%。 其結果’各裝置構成之溫度振幅的大小係（3X2X1)之 順序。再者，冷卻位置之溫度越高’各裝置構成間之溫度 振幅的差越大。此外於（1)之裝置構成中，於冷卻位置之溫 度為4.2K之情形，氦冷凝部20之溫度振幅抑制於±9 mK。 由上述之測定結果，確認了與（3)僅第2冷卻台14之裝置構 127199.doc -13· 200839162 成相比’（2)於追加了氦冷凝部2〇之裝置構成中溫度振幅顯 著下降，及（1)於追加了傳熱緩衝材料16及氦冷凝部2〇之裴 置構成中，與（2)相比温度振幅進一步下降。 圖3係顯不氦冷凝部中液體氦之容積比與溫度振幅之關 係的圖表。此處，測定了（1)與本實施形態同樣，設置了傳 熱緩衝材料之情形的溫度振幅（菱形圖案）與（2)未設置傳熱 緩衝材料之情形的溫度振幅（三角形圖案）。再者，將儲存 器30之容積設定為3250 cc、對儲存器3〇之氦氣的最大填充 壓力没定為0.48 MPa、冷卻位置之溫度設定為4.2K。 其結果，與液體氦之容積比無關，溫度振幅之大小為 (2)>(1)。此外，雖於無液體氦之情形溫度振幅變大，但於 即使存在很少液體氦之情形，溫度振幅變小。而且，於〇) 中液體氦之容積比例為1%〜3〇%之情形，氦冷凝部2〇之溫 度振幅均抑制於±9 mK。由上述確認了即使係少量之液體 氦，亦具有可大幅降低溫度振幅之效果。 且。兒本灵施形悲中，因設置了熱傳導率比氦冷凝部2〇低 之傳熱緩衝材料16，故認為冷凍機之冷凍能力下降。因 此，本申請案之發明人調查了因傳熱緩衝材料“之有無而 產生的冷凍能力差異。 圖4係顯示冷卻位置之溫度與冷卻位置之冷凍能力之關 係的圖表。此處，測定了（丨）與本實施形態同樣，設置了傳 熱緩衝材料16之情形的冷凍能力（菱形圖案）與（2)不設置傳 熱緩衝材料之情形的冷凍能力（四邊形圖案）。再者，將氦 冷凝部20内部之液體氦的容積比設定為20%。 127199.doc -14 - 200839162 之=二t冷卻位置之溫度無關，於有傳熱緩衝材㈣ 月/的冷;東能力下降率為25%左右。因此 能力之損失抑制於數十^了冷束 低Γ二本實施形態中’因設置了熱傳導率比氦冷凝部2。 :之傳熱緩衝材料16，故認為冷卻時間増加。目此 胃tmw查了因傳熱缓衝材料16之有無而 卻時間差異。 4 圖5係顯示冷卻時間與冷卻位置溫度之關係的圖表。此 處’測量了 (1)與本實施形態同樣，設置了傳熱緩衝材料之 情形的冷卻位置之溫度(實線)與⑺不設置傳熱緩衝材料之 情形的冷卻位置之溫度（四彡形圖案）。其結果，確認了幾 乎無因傳熱緩衝材料16之有無而產生的冷卻時間差異。 如以上所料，本實施形態相關之冷來機（參照圖1}係 於載置被冷卻物40之氦冷凝部2〇與第2冷卻台丨斗之間具備 由熱傳導率比氦冷凝部2G低之材料構成的傳熱緩衝材料16 之構成。若藉由此構成，則起因於心東機i之冷珠循環的 熱流脈動由氦冷凝部20中之氦的蒸發及冷凝（相轉移）所吸 收。此時，因傳熱緩衝材料16作為熱流之節流機構起作 用，故第2冷卻台14 t之溫度振幅的傳遞受到抑制，其結 果，可降低被冷卻物40之載置面上的溫度振幅。此外，因 第2冷部台14、傳熱緩衝材料16、氦冷凝部2〇及被冷卻物 40連續配置為同軸狀，故來自被冷卻物之傳熱流路因軸對 稱形狀而縮短了距離。因此，可對被冷卻物4〇進行均勻且 穩定之冷卻。 127199.doc •15- 200839162 此外’本實施形態中’可將氦冷凝部2〇中之液體氦⑽ 容積比抑制於鳩以m，可將填充氦氣5。之儲存器 30小型化。此外，彳降低對於儲存㈣之室温時的氣㈣ 填充壓力。其結果’即使冷珠⑴停止，氦冷凝部2〇之液 體氦52氣化’亦可防止儲存器3()及氦冷凝部形成高壓力。 [第2實施形態] 其次’就本發明之第2實施形態相關的冷凍機進行說 明。 圖6係本實施形態相關之冷凍機之氦冷凝部附近的概略 構成圖。本實施形態相關之冷凍機係於氦冷凝部22〇之内 面221、223立式設置散熱片222、224者。再者，關於與第 1實施形態同樣之構成的部分，省略其詳細說明。 於第2冷卻台14與被冷卻物40之間，配置有氦冷凝部 220 〇 氦冷凝部220係由銅、銀、鋁等材料構成之圓筒狀中空 容器，且於其内部填充有氦氣50。若藉由第2冷卻台14冷 卻氦冷凝部220，則氦氣冷凝並生成液體氦52。藉由此液 體氦5 2冷卻被冷卻物4 0。 於氦冷凝部220之内面立式設置有複數個散熱片222、 224。各散熱片222、224與氦冷凝部220同樣，宜由熱傳導 率高之材料構成。各散熱片222、224既可與氦冷凝部220 一體成形，亦可成形為另一體並固定於氦冷凝部22〇。 第1散熱片222自氦冷凝部220之底面221向頂面223形 成。藉此，可擴大氦冷凝部220之内面與液體氦52的接觸 127199.doc -16- 200839162 面積可效率佳地冷卻載置於氦冷凝部22q的被冷 卻物40。 、第熱片224自氦冷凝部22〇之頂面如向底面221形 成。藉此，可擴大氦冷凝部22G之内面與氦氣5()的接觸面 積因此，可效率佳地冷卻、冷凝氦冷凝部22〇之内部的 氦氣5 0。 [第3實施形態] 其次，就本發明之第3實施形態相關的冷凍機進行說 明。 圖7係本實施形態相關之冷凍機之氦冷凝部附近的概略 構成圖。本實施形態相關之冷凍機係於氦冷凝部32〇之内 面安裝多孔結構體322者。再者，關於與第！實施形態同樣 之構成的部分，省略其詳細說明。 於fL冷凝部320之内面安裝有多孔結構體322。多孔結構 體322由金屬網、發泡性金屬、燒結金屬等構成。多孔結 構體322既可填充於氦冷凝部320之内侧整體，亦可僅填充 於局部。 多孔結構體3 2 2以保持與乱冷凝部3 2 0之内面熱性良好接 觸的方式，藉由接合劑等安裝於氦冷凝部320之内面。 藉由設置多孔結構體322，可擴大氦冷凝部320之内面與 液體氦52的接觸面積。因此，可效率佳地冷卻載置於氦冷 凝部320之被冷卻物40。此外，藉由設置多孔結構體322， 可擴大氦冷凝部320之内面與氦氣50的接觸面積。因此， 可效率佳地冷卻、冷凝氦冷凝部320之内部的氦氣50。 127199.doc 200839162 [第4實施形態] 其次’就本發明之第4實施形態相關的冷珠機進行說 明。 圖8係本實施形悲相關之冷殊機之氦冷凝部附近的概略 構成圖。本實施形態相關之冷涞機係於傳熱緩衝材料16之 與第2冷卻台14的接觸面上形成凹凸18者。再者，關於與 第1實施形態同樣之構成的部分，省略其詳細戈明 傳熱缓衝材料16由熱傳導率較低之不銹鋼材料等構成。 於其與第2冷卻台14之接觸面上形成有凹凸18。凹凸“既 可有規則地形成，亦可無規則地（隨機）形成。此外，既可 將凹凸18形成為錘狀，以便與第2冷卻台14點接觸，亦可 將凹凸18形成為錘梯狀，以便與第2冷卻台14面接觸。此 外’既可以凹凸18為截面三角形之突條，以便與第2冷卻 台14線接觸，亦可以凹凸18為載面梯形，以便與第2冷卻 台14帶狀面接觸。 本只細形悲中，因於傳熱緩衝材料丨6之與第2冷卻台】4 的接觸面上形成凹凸18，故傳熱緩衝材料16與第2冷卻台 Μ之接觸面積變小。藉此’與傳熱緩衝材料16和第2冷卻 台14整面接觸之情形㈣，因熱流之節流機能被強化，故 可抑制第2冷部台14上之溫度振幅向氦冷凝部42。傳遞。因 此，可降低被冷卻物之載置面上的溫度振幅。 本實施形態中’雖於傳熱緩衝材料“之與第2冷卻台14 的接触面形成凹凸18 ’但亦可於第2冷卻台U之與傳熱緩 衝材枓16之接触面形成凹凸。此外，既可於傳熱緩衝材料 127199.doc -18- 200839162 16之與氦冷凝部420之接触面上形成凹凸，亦可於氨冷凝 部420之與傳熱緩衝材料16之接触面上形成凹凸。即，於 第2冷卻台14或氦冷凝部420與傳熱緩衝材料16之接触面上 形成凹凸即可。無論在任何情形中，均可抑制第2 △卻△ 14之溫度振幅向氦冷凝部420傳遞。因此，可降低被冷卻 物之載置面上的溫度振幅。 [苐5實施形態] 其次，就本發明之第5實施形態相關的冷束機進行說 明。 圖9係於本實施形態相關之冷凍機之氦冷凝部附近的概 略構成圖。本實施形態相關之冷凍機係具有安裝於氣冷凝 部520上之溫度感測器64及加熱器66與基於溫度感測器64 之測量結果驅動加熱器66之控制部62者。再者，關於與第 1實施形悲同樣之構成的部分’省略其詳細說明。 本實施形態中，於氦冷凝部520上之被冷卻物的載置 面附近安裝有溫度感測器64。此外，於氦冷凝部520安裝 有具備電熱線等之加熱器66。此等溫度感測器64及加熱器 66與控制部62連接。控制部62基於溫度感測器64之測量結 果驅動加熱器66。即，將溫度感測器64之輸出信號轉換為 加熱器66之驅動電流，此外使反饋電流流向加熱器66，藉 此進行控制，以便起因於其發熱之溫度脈動變得最小。 具體言之，首先比較被冷卻物4 0之載置面的設定溫度和 温度感測器6 4之測量溫度。於測量溫度低於設定溫度之情 形，驅動加熱器加熱氦冷凝部5 2 0。藉此，可使被冷卻物 127199.doc -19- 200839162 40之載置面的溫度上升，使之回歸至設定溫度。因此，可 降低被冷卻物4 0之載置面上的溫度振幅。 再者’本發明之技術範圍並非限於上述之實施形態者， 於不脫離本發明之宗旨的範圍内，包含對上述實施形態施 加各種變更者。即，實施形態中列舉之具體材料或構成等 僅為一例，可進行適當變更。 [產業上之可利用性] 可提供一種可降低被冷卻物之載置面上的溫度振幅，此 外可均勻且穩定地冷卻被冷卻物之冷;東機。 【圖式簡單說明】 圖1係顯示本發明第1實施形態相關之冷凍機的概略構成 圖。 圖2係顯示第2冷卻台之溫度與溫度振幅之關係的圖表。 圖3係顯不氦冷凝部中液體氦之容積比與溫度振幅之關 係的圖表。 圖4係顯示第2冷卻台之溫度與冷凍能力之關係的圖表。 圖5係顯示冷卻時間與第2冷卻台之温度之關係的圖表。 圖6係顯示本發明第2實施形態相關之冷凍機之氮冷凝部 附近的概略構成圖。 圖7係顯示本發明第3實施形態相關之冷凍機之氛冷凝部 附近的概略構成圖。 圖8係顯示本發明第4實施形態相關之冷凍機之氛冷凝部 附近的概略構成圖。 圖9係顯示本發明第5實施形態相關之冷凍機之氮冷凝部 127199.doc -20- 200839162 附近的概略構成圖。 【主要元件符號說明】 1 冷凍機 14 第2冷卻台（冷卻台） 16 傳熱緩衝材料 18 凹凸 20 氦冷凝部 30 儲存器 40 被冷卻物 5 0 氦氣 62 控制部 64 溫度感測器 66 加熱器 222 第1散熱片（散熱片） 224 第2散熱片（散熱片） 322 多孔結構體 127199.doc -21 -200839162 IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a refrigerator. [Prior Art] In order to measure the physical properties of the sample in an extremely low temperature environment around 4K, or to measure various physical quantities such as sensors using a very low temperature environment, GM is used for cooling; This cold; the east machine system cools the object to be cooled to a very low temperature by repeatedly compressing and expanding the refrigerant gas such as helium (cold; east cycle). However, due to the pulsation of the heat flow caused by the above-described refrigeration cycle, a temperature amplitude is generated on the surface on which the object to be cooled is placed. In order to stably cool the object to be cooled, it is desirable to lower this temperature amplitude. Patent Document 1 discloses a cryogenic refrigerator including a cooling unit that is provided with a cooling unit for mounting an object to be cooled, a helium gas or helium gas and a liquid helium, and a supply mechanism for connecting the compressed helium gas and the aforementioned The helium gas of the cold storage mechanism is introduced into the discharge mechanism. Patent Document 2 discloses an extremely low temperature temperature regulator including a helium gas introduction pipe that introduces a necessary amount of helium gas at a normal temperature, a condenser chamber that liquefies helium gas, and a liquid that stores a liquid helium that is liquefied. Diverticulum. [Patent Document 1] Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. Hei. No. 2-776955. Since the temperature amplitude is about 3 〇 mK, it is desirable that the temperature amplitude is further lowered. 127199.doc 200839162 On the other hand, the structure of the cryogenic temperature regulator of Patent Document 2 is complicated, and the heat transfer path from the coolant is long and non-axisymmetric, so that there is a problem that the cooling is uneven and unstable. The present invention has been made to solve the above problems, and an object of the invention is to provide a refrigerator capable of reducing the temperature amplitude of a surface on which a cooling object is placed, and capable of uniformly and stably cooling the object to be cooled. 7 [Technical means for solving the problem] In order to solve the above problems, the present invention employs the following means. That is, the cold machine of the present invention includes: a cooling stage that cools the object to be cooled; a condensing unit that carries the object to be cooled; and a reservoir that communicates with the enthalpy condensing portion and is filled with helium; And a heat transfer buffer material disposed between the cooling stage and the enthalpy condensation unit, and comprising a material having a lower thermal conductivity than the enthalpy condensation unit. According to this configuration, the heat flow pulsation caused by the refrigeration cycle of the refrigerator is absorbed by evaporation and condensation (phase transfer) of the crucible portion. At this time, since the heat transfer buffer material functions as a throttle mechanism for the heat flow, the transmission of the temperature amplitude of the cooling stage can be suppressed. As a result, the temperature amplitude of the surface to be cooled can be lowered. Further, since the cooling stage, the heat transfer buffer material, the enthalpy condensation portion, and the object to be cooled are continuously arranged coaxially, the object to be cooled can be uniformly and stably cooled. The enthalpy condensation portion may include a material having a thermal conductivity of 2 〇〇 W / (m · K) or more at a temperature of around 4K. According to this configuration, the object to be cooled can be efficiently cooled by the liquid enthalpy condensed in the condensing portion. 127199.doc 200839162 The aforementioned heat transfer buffer material may comprise a material having a thermal conductivity of less than 100 W/(m · Κ) at a temperature around 4K. By this configuration, the temperature amplitude of the cooling stage can be surely prevented from being transmitted. The volume of the enthalpy condensation unit may be 10 CC or more and 100 CC or less. According to this configuration, the storage volume of the liquid crucible necessary for cooling the object to be cooled can be ensured, and the crucible condensation portion can be miniaturized. The volume of the reservoir may be 5 times or more and 100 times or less the volume of the aforementioned enthalpy condensation portion. According to this configuration, the storage volume for cooling the object to be cooled can be ensured, and the reservoir can be miniaturized. It is really charged with the pressure of the above-mentioned nitrogen gas in the reservoir, at room temperature 〇.1馗匕 or more 1. () "1^ or less. For the ★ * - structure, even if the cold camera stops, the liquid enthalpy of the condensate is evaporated.丄Also prevent high pressure build-up in the reservoir and the enthalpy condensation section. / The heat sink can be placed vertically on the inner surface of the condensing section. The porous structure can be installed on the inner surface of the enthalpy condensing section. The composition, the purpose, the 丨m & and the person's condition are due to the contact between the inner surface of the cold-reduction part and the liquid helium: the product becomes large, so that the cooled and condensed portion placed in the gas condensation portion can be cooled with good effect. The heat transfer buffer material and the cooling table or the contact surface of the crucible can form irregularities. If the contact area formed by the heat transfer buffer material is reduced, the temperature amplitude transmission of the cooling stage can be suppressed by the heat transfer buffer material and the cooling stage or the crucible condensation portion. 127199.doc 200839162 As a result, the temperature amplitude of the surface to be cooled can be reduced. Further, the method further includes: a temperature sensor and a heater, which are mounted on the enthalpy condensing unit and the control unit, based on Measuring junction of the aforementioned temperature sensor When the heater is driven, if the temperature of the condensing portion is lower than a predetermined value, the heater can be driven to return the temperature of the enthalpy condensation portion to a predetermined value. Therefore, the mounting of the object to be cooled can be reduced. [Effect of the Invention] According to the present invention, by providing a heat transfer buffer material, the temperature amplitude of the cooling stage can be prevented from being transmitted, and as a result, the temperature of the surface on which the object to be cooled can be lowered can be lowered. In addition, since the cooling stage, the heat transfer buffer material, the enthalpy condensation unit, and the object to be cooled are continuously arranged coaxially, the object to be cooled can be uniformly and stably cooled. [Embodiment] Hereinafter, an embodiment of the present invention will be referred to. [First Embodiment] Fig. 1 is a schematic configuration diagram of a refrigerator according to a first embodiment of the present invention. The refrigerator 1 according to the present embodiment includes a second cooling stage that cools the object 4 to be cooled. 14; a condensing unit 20 for placing the object 40 to be cooled; a reservoir 30 filled with the helium gas 50 in communication with the enthalpy condensing unit 20; and a heat transfer rate between the second cooling stage 14 and the enthalpy condensing unit 20 ratio The heat transfer cushioning material 16 made of a material having a low condensing portion 2 is provided. The refrigerator 1 mainly includes a compressor 4, a main body portion 2, and a cooling portion 15. The compressor 4 compresses the low-pressure helium gas supplied from the low-pressure pipe 8. The high pressure 氦 127199.doc 200839162 is supplied to the high pressure pipe 6. The main body 2 switches the pressure in the pressure pipe 6 and the low pressure pipe 8 and the cooling unit 15 described below by the power of the motor or the like. The connector of the air flow path is connected to the main body 2, and is provided with a cooling unit 丨5. The cooling unit 丨5 is disposed inside the vacuum chamber 10 held in a vacuum environment, and is convinced by flowing through the inside. In the cooling unit, the fourth portion, the first cooling stage 12, the second cooling unit 13, and the second cooling stage 14 are sequentially provided in the cooling unit. The first cooling unit 11 and the second cooling unit 13 are formed in a columnar shape, and the first cooling stage 12 and the second cooling stage 14 are formed in a disk shape and disposed coaxially. Inside the cooling unit 1 $, a helium flow path (not shown) is formed. The compressed helium gas supplied to the helium gas flow path absorbs heat and expands on the second cooling stage 14 and changes to low pressure helium gas. A heat transfer cushioning material 16 is provided between the lower surface of the second cooling stage 14 and a enthalpy condensing unit 2 后 which will be described later. The heat transfer cushioning material 16 is formed, for example, in a plate shape having a diameter of about several tens of mm and a thickness of about 2 mm. The heat transfer buffer material 16 has a thermal conductivity lower than that of the enthalpy condensing unit 20 described later at a temperature of about 4 feet, and is made of a stainless steel material or the like. In particular, when the heat transfer buffer material 16 is made of a material having a thermal conductivity of less than 100 W/(m · K) at a temperature of around 4 K, the temperature amplitude of the second cooling stage 14 can be suppressed from being transmitted to the enthalpy condensation unit 2 〇. Further, in order to improve the thermal contact property, the two sides of the heat transfer buffer material 16 are attached, and the anchor 4 is connected, and the second cooling stage 14, the heat transfer buffer material 16, and the enthalpy condensation unit 20 are attached to the heat transfer buffer material 16. Next, the crucible condensing unit 20 on which the object to be cooled 4 is placed is provided. The heat transfer rate of the enthalpy condensing unit 2 at a temperature of about 4 feet is higher than that of the heat transfer buffering material 16 described above, and is made of a material such as copper, silver or aluminum. In the embodiment 127199.doc 200839162, the ruthenium condensation portion 20 is formed by oxygen-free copper. In particular, if the enthalpy condensing unit 20 is made of a material having a thermal conductivity of 200 W/(m· Κ) or more at a temperature of around 4 K, the condensed liquid enthalpy in the condensing unit 20 can be cooled by cooling efficiently. Object 40. The 氦 condensing portion 20 is formed in a cylindrical shape in which both ends are sealed, and the liquid enthalpy is stored therein. When the volume of the enthalpy condensing unit 20 is 10 cc or more and 1 sec or less, the storage volume of the liquid enthalpy necessary for cooling the object 40 to be cooled can be secured, and the enthalpy condensing unit 20 can be miniaturized. In the present embodiment, the volume of the enthalpy condensing unit 2 is set to 40 cc. Below the condensing unit 20, a table 41 is disposed. The lower surface of the table 41 serves as a cooling position at the place where the object 40 to be cooled is placed. The table 4 is composed of a material having the same physical properties as the crucible condensing portion 20. In the present embodiment, indium foil or the like is attached between the crucible condensing unit 20 and the stage 41, and between the stage 41 and the object 40 to be cooled, and the crucible condensing unit 2 is connected to the table 41. Further, the table 4 1 may not be provided, and the object 40 to be thermally contacted may be attached to the enthalpy condensing portion 20 with good thermal contact. The second cooling stage 14, the heat transfer buffer material 丨6, the 冷凝 condensing unit 20, and the object to be cooled 40 of the cooling unit 15 described above constitute a heat transfer passage from the object to be cooled. In the present embodiment, by continuously arranging these to be coaxial, the distance of the heat transfer path can be shortened. Thereby, the cooling loss can be reduced, and the object to be cooled 40 can be efficiently cooled to the target temperature in a short time. Further, the heat transfer passage can be formed in an axisymmetric shape to uniformly and stably cool the entire object to be cooled. The thin tube 32 is extended from the enthalpy condensing portion 20 and is always connected to the storage; 杳 & disposed outside the vacuum _ 127199.doc 11 200839162 1 . The volume of the reservoir 30 is preferably 5 立 立 μ 氦 氦 氦 〇 〇 〇 〇 〇 〇 〇 〇 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 The storage volume of the helium gas necessary for cooling the object to be cooled can be ensured, and the reservoir 30 can be miniaturized. - The inside of the reservoir 30 is filled with helium gas. This helium gas is at room temperature and In the present embodiment, the helium gas 5 屋 having a house force of 〇 4 Mpa at room temperature is filled in the reservoir 3 〇. Therefore, even if the cold beam machine 1 stops the 氦 condensing unit 20 When the liquid helium 52 evaporates, the reservoir 3 does not form a high pressure. Further, in the middle portion of the thin tube 32, a heat holder 34 for heat exchange with the first cooling stage 12 is formed. The operation of the refrigerator 1 described above is explained. As described above, the high-pressure helium gas supplied from the compressor 4 to the cooling unit 15 absorbs heat and expands on the second cooling stage 14 and changes to low-pressure helium gas. The main body unit 2 continuously switches the high-pressure piping. 6 and the connection of the low-pressure pipe 8 and the enthalpy flow path of the cooling unit 15. The compression and expansion of the helium gas (refrigeration cycle) causes the temperature of the second cooling stage 14 to become extremely low. The lower condensing unit 2 is provided below the second cooling stage 14 and is cooled by the second cooling stage 14 In the condensing unit 20, the helium gas inside the enthalpy condensing unit 20 is condensed and liquefied to generate a liquid enthalpy 52. In the present embodiment, the volume ratio to the enthalpy condensing unit 2 is 30% or less (for example, about 20%). The method generates liquid 氦0 and says that the temperature fluctuation occurs in the second cooling stage 14 due to the heat flow pulsation caused by the above-described refrigeration cycle. However, in the present embodiment, the heat flow pulsation due to the cold-to-east cycle is caused by evaporation and condensation of the enthalpy. (phase transfer) is absorbed. -12-127199.doc 200839162 This does not cause the same temperature amplitude as that of the second cooling stage 14 in the enthalpy condensing unit 20, and the temperature amplitude of the enthalpy condensing unit 20 becomes small. A heat transfer buffer material 16 formed of a material having a lower thermal conductivity than the enthalpy condensation unit 20 is provided between the second cooling stage 14 and the enthalpy condensation unit 2A. The heat transfer buffer material 16 is used as a heat flow throttling. Institutions play a role, so they can be suppressed 2 The temperature amplitude of the cooling stage 14 is transmitted to the enthalpy condensing unit 20. Therefore, the temperature amplitude of the surface to be cooled can be lowered. Fig. 2 is a graph showing the relationship between the temperature of the second cooling stage and the temperature amplitude. The temperature amplitude was measured for the three types of devices. Specifically, (1) the enthalpy condensing unit 20 in the case where the second cooling stage 14, the heat transfer buffer material 16, and the enthalpy condensing unit 20 were provided in the same manner as in the present embodiment was measured. Temperature amplitude (diamond pattern), (2) no heat transfer buffer material 16 is provided, and the temperature amplitude (triangular pattern) of the enthalpy condensing unit 20 in the case where the second cooling stage 14 and the chilling reduction unit 20 are provided, And (3) the temperature amplitude (circular pattern) of the second cooling stage 14 in the case where the heat transfer buffer material 16 and the enthalpy condensation unit 2 are not provided. The horizontal axis represents the temperature at which the cooling position (measurement position of the temperature amplitude) of the object to be cooled is placed. Further, the volume of the reservoir 30 was set to 3250 cc, the helium filling pressure to the reservoir 3 was set to 0.4 Mp a, and the liquid helium volume ratio inside the enthalpy condensing section 20 was set to 20%. As a result, the magnitude of the temperature amplitude of each device configuration is (3X2X1). Further, the higher the temperature at the cooling position, the greater the difference in temperature amplitude between the respective device configurations. Further, in the device configuration of (1), when the temperature at the cooling position is 4.2 K, the temperature amplitude of the enthalpy condensing portion 20 is suppressed to ±9 mK. As a result of the measurement described above, it was confirmed that (2) the temperature of the device structure of the second cooling stage 14 is higher than that of the device structure 127199.doc -13·200839162 of the second cooling stage 14 In the configuration in which the heat transfer buffer material 16 and the enthalpy condensation unit 2 are added, the temperature amplitude is further lowered as compared with (2). Figure 3 is a graph showing the relationship between the volume ratio of liquid helium in the condensing section and the temperature amplitude. Here, (1) a temperature amplitude (diamond pattern) in the case where the heat transfer buffer material is provided and (2) a temperature amplitude (triangle pattern) in the case where the heat transfer buffer material is not provided, as in the present embodiment. Further, the volume of the reservoir 30 was set to 3,250 cc, the maximum filling pressure of the helium gas to the reservoir 3 was not set to 0.48 MPa, and the temperature of the cooling position was set to 4.2K. As a result, regardless of the volume ratio of the liquid helium, the magnitude of the temperature amplitude is (2) > (1). Further, although the temperature amplitude becomes large in the absence of liquid helium, the temperature amplitude becomes small even in the case where there is little liquid helium. Further, in the case where the volume ratio of the liquid helium is 1% to 3〇%, the temperature amplitude of the helium condensing unit 2〇 is suppressed to ±9 mK. From the above, it was confirmed that even a small amount of liquid enthalpy has an effect of greatly reducing the temperature amplitude. And. In the case of the child's sorrow, since the heat transfer buffer material 16 having a lower thermal conductivity than the 氦 condensation portion 2 is provided, the refrigeration capacity of the refrigerator is considered to be lowered. Therefore, the inventors of the present application investigated the difference in the freezing ability due to the presence or absence of the heat transfer cushioning material. Fig. 4 is a graph showing the relationship between the temperature of the cooling position and the freezing ability of the cooling position. Here,丨) In the same manner as in the present embodiment, the freezing ability (diamond pattern) in the case where the heat transfer buffer material 16 is provided and (2) the freezing ability (quadrilateral pattern) in the case where the heat transfer buffer material is not provided are provided. Further, the crucible is condensed. The volume ratio of the liquid helium inside the portion 20 is set to 20%. 127199.doc -14 - 200839162 = the temperature of the second cooling position is irrelevant, there is a heat transfer cushioning material (four) month / cold; the east capacity decline rate is 25% Therefore, the loss of the capacity is suppressed in the tens of thousands of cold beams. In the present embodiment, the cooling time is considered to be due to the heat transfer buffer material 16 which is provided with the thermal conductivity ratio 氦 condensing unit 2. Tmw checks the time difference due to the presence or absence of the heat transfer buffer material. 4 Fig. 5 is a graph showing the relationship between the cooling time and the cooling position temperature. Here, '1' is measured as in the present embodiment, and the transmission is set. heat The temperature of the cooling position in the case of the buffer material (solid line) and (7) the temperature of the cooling position in the case where the heat transfer buffer material is not provided (tetragonal pattern). As a result, it was confirmed that there was almost no presence or absence of the heat transfer buffer material 16 The difference in the cooling time is as follows. As described above, the cold-rolling machine according to the present embodiment (see FIG. 1) is provided between the enthalpy condensing unit 2 载 on which the object 40 to be cooled is placed and the second cooling stage hopper The heat transfer buffer material 16 having a thermal conductivity lower than that of the enthalpy condensing portion 2G is constituted by the heat pulsation of the cold bead cycle caused by the core machine i by the enthalpy of the enthalpy in the condensing portion 20 At the same time, since the heat transfer buffer material 16 functions as a throttling mechanism for the heat flow, the transmission of the temperature amplitude of the second cooling stage 14 t is suppressed, and as a result, the object to be cooled can be lowered. Temperature amplitude on the mounting surface of 40. Further, since the second cold stage 14, the heat transfer buffer 16, the enthalpy condensing unit 2, and the object 40 to be cooled are continuously arranged coaxially, heat transfer from the object to be cooled is performed. The flow path is shortened due to the axisymmetric shape Therefore, it is possible to uniformly and stably cool the object to be cooled. 127199.doc •15- 200839162 Further, in the present embodiment, the volume ratio of the liquid helium (10) in the enthalpy condensing unit 2 can be suppressed to m, the reservoir 30 filled with helium gas 5 can be miniaturized. In addition, the gas (four) filling pressure at room temperature (4) is lowered. As a result, even if the cold beads (1) are stopped, the liquid 氦 52 of the condensing portion 2 is closed. In the second embodiment of the present invention, the refrigerator according to the second embodiment of the present invention will be described. A schematic configuration of the vicinity of the condensing unit of the refrigerator. The refrigerator according to the present embodiment is provided with fins 222 and 224 which are provided vertically on the inner faces 221 and 223 of the enthalpy condensing unit 22A. Further, the detailed description of the same components as those of the first embodiment will be omitted. Between the second cooling stage 14 and the object 40 to be cooled, a 氦 condensation unit 220 is disposed. The condensing unit 220 is a cylindrical hollow container made of a material such as copper, silver or aluminum, and is filled with helium gas. 50. When the condensing unit 220 is cooled by the second cooling stage 14, the helium gas is condensed to form a liquid helium 52. The object to be cooled 40 is cooled by the liquid crucible 52. A plurality of fins 222 and 224 are vertically disposed on the inner surface of the enthalpy 220. Similarly to the crucible condensing unit 220, each of the fins 222 and 224 is preferably made of a material having a high thermal conductivity. Each of the fins 222 and 224 may be integrally formed with the crucible condensing portion 220, or may be formed into another body and fixed to the crucible condensing portion 22A. The first fins 222 are formed from the bottom surface 221 of the enthalpy condensing portion 220 toward the top surface 223. Thereby, the contact between the inner surface of the crucible condensing portion 220 and the liquid helium 52 can be enlarged. 127199.doc -16 - 200839162 The area can efficiently cool the cooled object 40 placed on the crucible condensing portion 22q. The hot sheet 224 is formed from the top surface of the enthalpy condensing portion 22, for example, toward the bottom surface 221 . Thereby, the contact area between the inner surface of the enthalpy condensing portion 22G and the helium gas 5 () can be enlarged, so that the helium gas 50 inside the condensing portion 22 can be efficiently cooled and condensed. [Third embodiment] Next, a refrigerator according to a third embodiment of the present invention will be described. Fig. 7 is a schematic configuration diagram of the vicinity of the enthalpy condensation portion of the refrigerator according to the embodiment. In the refrigerator according to the present embodiment, the porous structure 322 is attached to the inside of the crucible condensing unit 32. Furthermore, about the first! The same components of the embodiment are omitted, and detailed description thereof will be omitted. A porous structure 322 is attached to the inner surface of the fL condensing portion 320. The porous structure 322 is composed of a metal mesh, a foamable metal, a sintered metal or the like. The porous structure 322 may be filled in the entire inner side of the crucible condensing portion 320 or may be filled only in a part. The porous structure 3 2 2 is attached to the inner surface of the crucible condensing unit 320 by a bonding agent or the like so as to maintain good thermal contact with the inner surface of the chaotic condensation portion 320. By providing the porous structure 322, the contact area between the inner surface of the crucible condensing portion 320 and the liquid helium 52 can be enlarged. Therefore, the object 40 to be cooled placed on the crucible cooling portion 320 can be efficiently cooled. Further, by providing the porous structure 322, the contact area between the inner surface of the crucible condensing portion 320 and the helium gas 50 can be enlarged. Therefore, the helium gas 50 inside the enthalpy condensation portion 320 can be efficiently cooled and condensed. 127199.doc 200839162 [Fourth embodiment] Next, a cold bead machine according to a fourth embodiment of the present invention will be described. Fig. 8 is a schematic view showing the vicinity of the enthalpy of the enthalpy of the cold-related machine of the present embodiment. The cold heading machine according to the present embodiment is formed by forming the unevenness 18 on the contact surface of the heat transfer cushioning material 16 with the second cooling stage 14. Further, the portion of the configuration similar to that of the first embodiment is omitted, and the detailed heat transfer buffer material 16 is made of a stainless steel material having a low thermal conductivity. Concavities and convexities 18 are formed on the contact surface with the second cooling stage 14. The unevenness "may be formed regularly or irregularly (randomly). Further, the unevenness 18 may be formed in a hammer shape so as to be in point contact with the second cooling stage 14, or the unevenness 18 may be formed as a hammer ladder. In order to be in surface contact with the second cooling stage 14. In addition, the protrusions 18 may be in the shape of a triangle having a triangular cross section so as to be in line contact with the second cooling stage 14, or the unevenness 18 may be trapezoidal on the carrier surface so as to be in contact with the second cooling stage. 14 strip-shaped surface contact. This thin shape is sorrowful, because the heat-dissipating buffer material 丨6 and the second cooling table 】 4 contact surface forming irregularities 18, so the heat transfer buffer material 16 and the second cooling stage The contact area is reduced. By the fact that the heat transfer buffer material 16 and the second cooling stage 14 are in contact with the entire surface (4), since the throttling function of the heat flow is enhanced, the temperature amplitude on the second cold stage 14 can be suppressed. The condensing portion 42 is transferred. Therefore, the temperature amplitude of the surface on which the object to be cooled is placed can be reduced. In the present embodiment, the surface of the contact portion with the second cooling stage 14 is formed in the heat transfer cushioning material. It can also be in contact with the heat transfer buffer 枓16 of the second cooling stage U. Bump. In addition, irregularities may be formed on the contact surface of the heat transfer buffer material 127199.doc -18-200839162 16 with the enthalpy condensation portion 420, and bumps may be formed on the contact surface of the ammonia condensation portion 420 with the heat transfer buffer material 16. . In other words, irregularities may be formed on the contact surface between the second cooling stage 14 or the enthalpy condensation unit 420 and the heat transfer buffer material 16. In any case, the temperature amplitude of the second Δ but Δ 14 can be suppressed from being transmitted to the enthalpy condensing unit 420. Therefore, the temperature amplitude of the surface to be cooled can be lowered. [Embodiment 5] Next, a cold beam machine according to a fifth embodiment of the present invention will be described. Fig. 9 is a schematic configuration diagram of the vicinity of the enthalpy condensation portion of the refrigerator according to the embodiment. The refrigerator according to the present embodiment has a temperature sensor 64 and a heater 66 attached to the air condensing unit 520 and a control unit 62 that drives the heater 66 based on the measurement result of the temperature sensor 64. In addition, the detailed description of the same components as those of the first embodiment will be omitted. In the present embodiment, the temperature sensor 64 is attached to the vicinity of the mounting surface of the object to be cooled on the enthalpy condensing unit 520. Further, a heater 66 having a heating wire or the like is attached to the enthalpy condensing unit 520. The temperature sensor 64 and the heater 66 are connected to the control unit 62. The control unit 62 drives the heater 66 based on the measurement result of the temperature sensor 64. Namely, the output signal of the temperature sensor 64 is converted into the drive current of the heater 66, and the feedback current is also supplied to the heater 66, whereby the control is performed so that the temperature pulsation due to the heat generation thereof becomes minimum. Specifically, first, the set temperature of the mounting surface of the object 40 to be cooled and the measured temperature of the temperature sensor 64 are compared. In the case where the measured temperature is lower than the set temperature, the heater is driven to heat the condensing portion 520. Thereby, the temperature of the mounting surface of the object to be cooled 127199.doc -19- 200839162 40 can be raised to return to the set temperature. Therefore, the temperature amplitude of the surface to be cooled 40 can be lowered. Further, the technical scope of the present invention is not limited to the above-described embodiments, and various modifications may be made to the above-described embodiments without departing from the scope of the invention. That is, the specific materials, configurations, and the like listed in the embodiments are merely examples, and can be appropriately changed. [Industrial Applicability] It is possible to provide a temperature which can reduce the temperature amplitude on the surface on which the object to be cooled is cooled, and which can uniformly and stably cool the object to be cooled. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic block diagram showing a refrigerator according to a first embodiment of the present invention. Fig. 2 is a graph showing the relationship between the temperature of the second cooling stage and the temperature amplitude. Figure 3 is a graph showing the relationship between the volume ratio of liquid helium in the condensing section and the temperature amplitude. Fig. 4 is a graph showing the relationship between the temperature of the second cooling stage and the freezing capacity. Fig. 5 is a graph showing the relationship between the cooling time and the temperature of the second cooling stage. Fig. 6 is a schematic block diagram showing the vicinity of a nitrogen condensation unit of a refrigerator according to a second embodiment of the present invention. Fig. 7 is a schematic block diagram showing the vicinity of an atmosphere condensation portion of a refrigerator according to a third embodiment of the present invention. Fig. 8 is a schematic block diagram showing the vicinity of an atmosphere condensation portion of a refrigerator according to a fourth embodiment of the present invention. Fig. 9 is a schematic configuration view showing a vicinity of a nitrogen condensation unit 127199.doc -20- 200839162 of a refrigerator according to a fifth embodiment of the present invention. [Description of main component symbols] 1 Freezer 14 2nd cooling stage (cooling stage) 16 Heat transfer buffer material 18 Concavity and convexity 20 氦 Condensation part 30 Reservoir 40 Coolant 5 0 Helium 62 Control part 64 Temperature sensor 66 Heating 222 first heat sink (heat sink) 224 second heat sink (heat sink) 322 porous structure 127199.doc -21 -