{"product_id":"dilutra-dilution-refrigerator","title":"Dilutra – The Dilution Refrigerator \/ 6.4–6.6% ³He Physics Sticker","description":"\u003cp\u003eDilutra, a frost-haired keeper of the cold, holds a tiered golden chandelier glowing in the dark.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eBelow about 0.87 K a mixture of helium-3 and helium-4 separates into a ³He-rich phase floating on a dilute phase. Even at absolute zero the dilute phase keeps a few percent of ³He dissolved. Ifft, Edwards and Sarwinski measured this limit at 6.37 ± 0.05% (Phys. Rev. Lett. 19, 831, 1967); later work gives about 6.4–6.6% depending on pressure. Pumping ³He out of the dilute phase pulls more across the boundary, and that ‘evaporation’ into the dilute phase absorbs heat. It works continuously, down to a few millikelvin.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003ex\u003csub\u003e3\u003c\/sub\u003e(T → 0) ≈ 6.4–6.6%\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\u003cli\u003ex\u003csub\u003e3\u003c\/sub\u003e: fraction of ³He atoms in the dilute (⁴He-rich) phase\u003c\/li\u003e\u003c\/ul\u003e\u003cp\u003eThis is not a compression cycle: nothing is squeezed. The cooling comes from ³He crossing a phase boundary inside the mixing chamber.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The finite solubility at T = 0 is what keeps the cooling power from vanishing; real fridges are limited by heat leaks and exchanger performance.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003eDilutra cups a golden chandelier of stacked plates, the stages of a dilution refrigerator. Printed text: \u003cstrong\u003eDILUTRA\u003c\/strong\u003e with the line \u003cstrong\u003e6.4-6.6% ³He\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964054409319,"sku":"31947795011289156631","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964054442087,"sku":"12926282911806734578","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964054474855,"sku":"31617006025729007795","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964054507623,"sku":"20919618294854086513","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/5257801044577651272_1200.jpg?v=1793658920","url":"https:\/\/pixelatedphysics.com\/zh-hant\/products\/dilutra-dilution-refrigerator","provider":"Pixelated Physics","version":"1.0","type":"link"}